Moved, renamed, and deleted files

The original directory structure was scattered and unorganized.
Changes are basically to make it look like kernel structure.

1 files changed, 3316 insertions, 0 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
new file mode 100644
index 00000000..1dd48f7e
--- /dev/null
+++ b/kernel/signal.c
@@ -0,0 +1,3316 @@
+/*
+ *  linux/kernel/signal.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ *
+ *  1997-11-02  Modified for POSIX.1b signals by Richard Henderson
+ *
+ *  2003-06-02  Jim Houston - Concurrent Computer Corp.
+ *		Changes to use preallocated sigqueue structures
+ *		to allow signals to be sent reliably.
+ */
+
+#include <linux/slab.h>
+#include <linux/export.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/fs.h>
+#include <linux/tty.h>
+#include <linux/binfmts.h>
+#include <linux/security.h>
+#include <linux/syscalls.h>
+#include <linux/ptrace.h>
+#include <linux/signal.h>
+#include <linux/signalfd.h>
+#include <linux/ratelimit.h>
+#include <linux/tracehook.h>
+#include <linux/capability.h>
+#include <linux/freezer.h>
+#include <linux/pid_namespace.h>
+#include <linux/nsproxy.h>
+#include <linux/user_namespace.h>
+#define CREATE_TRACE_POINTS
+#include <trace/events/signal.h>
+
+#include <asm/param.h>
+#include <asm/uaccess.h>
+#include <asm/unistd.h>
+#include <asm/siginfo.h>
+#include <asm/cacheflush.h>
+#include "audit.h"	/* audit_signal_info() */
+
+/*
+ * SLAB caches for signal bits.
+ */
+
+static struct kmem_cache *sigqueue_cachep;
+
+int print_fatal_signals __read_mostly;
+
+static void __user *sig_handler(struct task_struct *t, int sig)
+{
+	return t->sighand->action[sig - 1].sa.sa_handler;
+}
+
+static int sig_handler_ignored(void __user *handler, int sig)
+{
+	/* Is it explicitly or implicitly ignored? */
+	return handler == SIG_IGN ||
+		(handler == SIG_DFL && sig_kernel_ignore(sig));
+}
+
+static int sig_task_ignored(struct task_struct *t, int sig, bool force)
+{
+	void __user *handler;
+
+	handler = sig_handler(t, sig);
+
+	if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
+			handler == SIG_DFL && !force)
+		return 1;
+
+	return sig_handler_ignored(handler, sig);
+}
+
+static int sig_ignored(struct task_struct *t, int sig, bool force)
+{
+	/*
+	 * Blocked signals are never ignored, since the
+	 * signal handler may change by the time it is
+	 * unblocked.
+	 */
+	if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
+		return 0;
+
+	if (!sig_task_ignored(t, sig, force))
+		return 0;
+
+	/*
+	 * Tracers may want to know about even ignored signals.
+	 */
+	return !t->ptrace;
+}
+
+/*
+ * Re-calculate pending state from the set of locally pending
+ * signals, globally pending signals, and blocked signals.
+ */
+static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
+{
+	unsigned long ready;
+	long i;
+
+	switch (_NSIG_WORDS) {
+	default:
+		for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
+			ready |= signal->sig[i] &~ blocked->sig[i];
+		break;
+
+	case 4: ready  = signal->sig[3] &~ blocked->sig[3];
+		ready |= signal->sig[2] &~ blocked->sig[2];
+		ready |= signal->sig[1] &~ blocked->sig[1];
+		ready |= signal->sig[0] &~ blocked->sig[0];
+		break;
+
+	case 2: ready  = signal->sig[1] &~ blocked->sig[1];
+		ready |= signal->sig[0] &~ blocked->sig[0];
+		break;
+
+	case 1: ready  = signal->sig[0] &~ blocked->sig[0];
+	}
+	return ready !=	0;
+}
+
+#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
+
+static int recalc_sigpending_tsk(struct task_struct *t)
+{
+	if ((t->jobctl & JOBCTL_PENDING_MASK) ||
+	    PENDING(&t->pending, &t->blocked) ||
+	    PENDING(&t->signal->shared_pending, &t->blocked)) {
+		set_tsk_thread_flag(t, TIF_SIGPENDING);
+		return 1;
+	}
+	/*
+	 * We must never clear the flag in another thread, or in current
+	 * when it's possible the current syscall is returning -ERESTART*.
+	 * So we don't clear it here, and only callers who know they should do.
+	 */
+	return 0;
+}
+
+/*
+ * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
+ * This is superfluous when called on current, the wakeup is a harmless no-op.
+ */
+void recalc_sigpending_and_wake(struct task_struct *t)
+{
+	if (recalc_sigpending_tsk(t))
+		signal_wake_up(t, 0);
+}
+
+void recalc_sigpending(void)
+{
+	if (!recalc_sigpending_tsk(current) && !freezing(current))
+		clear_thread_flag(TIF_SIGPENDING);
+
+}
+
+/* Given the mask, find the first available signal that should be serviced. */
+
+#define SYNCHRONOUS_MASK \
+	(sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
+	 sigmask(SIGTRAP) | sigmask(SIGFPE))
+
+int next_signal(struct sigpending *pending, sigset_t *mask)
+{
+	unsigned long i, *s, *m, x;
+	int sig = 0;
+
+	s = pending->signal.sig;
+	m = mask->sig;
+
+	/*
+	 * Handle the first word specially: it contains the
+	 * synchronous signals that need to be dequeued first.
+	 */
+	x = *s &~ *m;
+	if (x) {
+		if (x & SYNCHRONOUS_MASK)
+			x &= SYNCHRONOUS_MASK;
+		sig = ffz(~x) + 1;
+		return sig;
+	}
+
+	switch (_NSIG_WORDS) {
+	default:
+		for (i = 1; i < _NSIG_WORDS; ++i) {
+			x = *++s &~ *++m;
+			if (!x)
+				continue;
+			sig = ffz(~x) + i*_NSIG_BPW + 1;
+			break;
+		}
+		break;
+
+	case 2:
+		x = s[1] &~ m[1];
+		if (!x)
+			break;
+		sig = ffz(~x) + _NSIG_BPW + 1;
+		break;
+
+	case 1:
+		/* Nothing to do */
+		break;
+	}
+
+	return sig;
+}
+
+static inline void print_dropped_signal(int sig)
+{
+	static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
+
+	if (!print_fatal_signals)
+		return;
+
+	if (!__ratelimit(&ratelimit_state))
+		return;
+
+	printk(KERN_INFO "%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
+				current->comm, current->pid, sig);
+}
+
+/**
+ * task_set_jobctl_pending - set jobctl pending bits
+ * @task: target task
+ * @mask: pending bits to set
+ *
+ * Clear @mask from @task->jobctl.  @mask must be subset of
+ * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
+ * %JOBCTL_TRAPPING.  If stop signo is being set, the existing signo is
+ * cleared.  If @task is already being killed or exiting, this function
+ * becomes noop.
+ *
+ * CONTEXT:
+ * Must be called with @task->sighand->siglock held.
+ *
+ * RETURNS:
+ * %true if @mask is set, %false if made noop because @task was dying.
+ */
+bool task_set_jobctl_pending(struct task_struct *task, unsigned int mask)
+{
+	BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
+			JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
+	BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
+
+	if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
+		return false;
+
+	if (mask & JOBCTL_STOP_SIGMASK)
+		task->jobctl &= ~JOBCTL_STOP_SIGMASK;
+
+	task->jobctl |= mask;
+	return true;
+}
+
+/**
+ * task_clear_jobctl_trapping - clear jobctl trapping bit
+ * @task: target task
+ *
+ * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
+ * Clear it and wake up the ptracer.  Note that we don't need any further
+ * locking.  @task->siglock guarantees that @task->parent points to the
+ * ptracer.
+ *
+ * CONTEXT:
+ * Must be called with @task->sighand->siglock held.
+ */
+void task_clear_jobctl_trapping(struct task_struct *task)
+{
+	if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
+		task->jobctl &= ~JOBCTL_TRAPPING;
+		wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
+	}
+}
+
+/**
+ * task_clear_jobctl_pending - clear jobctl pending bits
+ * @task: target task
+ * @mask: pending bits to clear
+ *
+ * Clear @mask from @task->jobctl.  @mask must be subset of
+ * %JOBCTL_PENDING_MASK.  If %JOBCTL_STOP_PENDING is being cleared, other
+ * STOP bits are cleared together.
+ *
+ * If clearing of @mask leaves no stop or trap pending, this function calls
+ * task_clear_jobctl_trapping().
+ *
+ * CONTEXT:
+ * Must be called with @task->sighand->siglock held.
+ */
+void task_clear_jobctl_pending(struct task_struct *task, unsigned int mask)
+{
+	BUG_ON(mask & ~JOBCTL_PENDING_MASK);
+
+	if (mask & JOBCTL_STOP_PENDING)
+		mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
+
+	task->jobctl &= ~mask;
+
+	if (!(task->jobctl & JOBCTL_PENDING_MASK))
+		task_clear_jobctl_trapping(task);
+}
+
+/**
+ * task_participate_group_stop - participate in a group stop
+ * @task: task participating in a group stop
+ *
+ * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
+ * Group stop states are cleared and the group stop count is consumed if
+ * %JOBCTL_STOP_CONSUME was set.  If the consumption completes the group
+ * stop, the appropriate %SIGNAL_* flags are set.
+ *
+ * CONTEXT:
+ * Must be called with @task->sighand->siglock held.
+ *
+ * RETURNS:
+ * %true if group stop completion should be notified to the parent, %false
+ * otherwise.
+ */
+static bool task_participate_group_stop(struct task_struct *task)
+{
+	struct signal_struct *sig = task->signal;
+	bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
+
+	WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
+
+	task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
+
+	if (!consume)
+		return false;
+
+	if (!WARN_ON_ONCE(sig->group_stop_count == 0))
+		sig->group_stop_count--;
+
+	/*
+	 * Tell the caller to notify completion iff we are entering into a
+	 * fresh group stop.  Read comment in do_signal_stop() for details.
+	 */
+	if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
+		sig->flags = SIGNAL_STOP_STOPPED;
+		return true;
+	}
+	return false;
+}
+
+/*
+ * allocate a new signal queue record
+ * - this may be called without locks if and only if t == current, otherwise an
+ *   appropriate lock must be held to stop the target task from exiting
+ */
+static struct sigqueue *
+__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
+{
+	struct sigqueue *q = NULL;
+	struct user_struct *user;
+
+	/*
+	 * Protect access to @t credentials. This can go away when all
+	 * callers hold rcu read lock.
+	 */
+	rcu_read_lock();
+	user = get_uid(__task_cred(t)->user);
+	atomic_inc(&user->sigpending);
+	rcu_read_unlock();
+
+	if (override_rlimit ||
+	    atomic_read(&user->sigpending) <=
+			task_rlimit(t, RLIMIT_SIGPENDING)) {
+		q = kmem_cache_alloc(sigqueue_cachep, flags);
+	} else {
+		print_dropped_signal(sig);
+	}
+
+	if (unlikely(q == NULL)) {
+		atomic_dec(&user->sigpending);
+		free_uid(user);
+	} else {
+		INIT_LIST_HEAD(&q->list);
+		q->flags = 0;
+		q->user = user;
+	}
+
+	return q;
+}
+
+static void __sigqueue_free(struct sigqueue *q)
+{
+	if (q->flags & SIGQUEUE_PREALLOC)
+		return;
+	atomic_dec(&q->user->sigpending);
+	free_uid(q->user);
+	kmem_cache_free(sigqueue_cachep, q);
+}
+
+void flush_sigqueue(struct sigpending *queue)
+{
+	struct sigqueue *q;
+
+	sigemptyset(&queue->signal);
+	while (!list_empty(&queue->list)) {
+		q = list_entry(queue->list.next, struct sigqueue , list);
+		list_del_init(&q->list);
+		__sigqueue_free(q);
+	}
+}
+
+/*
+ * Flush all pending signals for a task.
+ */
+void __flush_signals(struct task_struct *t)
+{
+	clear_tsk_thread_flag(t, TIF_SIGPENDING);
+	flush_sigqueue(&t->pending);
+	flush_sigqueue(&t->signal->shared_pending);
+}
+
+void flush_signals(struct task_struct *t)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&t->sighand->siglock, flags);
+	__flush_signals(t);
+	spin_unlock_irqrestore(&t->sighand->siglock, flags);
+}
+
+static void __flush_itimer_signals(struct sigpending *pending)
+{
+	sigset_t signal, retain;
+	struct sigqueue *q, *n;
+
+	signal = pending->signal;
+	sigemptyset(&retain);
+
+	list_for_each_entry_safe(q, n, &pending->list, list) {
+		int sig = q->info.si_signo;
+
+		if (likely(q->info.si_code != SI_TIMER)) {
+			sigaddset(&retain, sig);
+		} else {
+			sigdelset(&signal, sig);
+			list_del_init(&q->list);
+			__sigqueue_free(q);
+		}
+	}
+
+	sigorsets(&pending->signal, &signal, &retain);
+}
+
+void flush_itimer_signals(void)
+{
+	struct task_struct *tsk = current;
+	unsigned long flags;
+
+	spin_lock_irqsave(&tsk->sighand->siglock, flags);
+	__flush_itimer_signals(&tsk->pending);
+	__flush_itimer_signals(&tsk->signal->shared_pending);
+	spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
+}
+
+void ignore_signals(struct task_struct *t)
+{
+	int i;
+
+	for (i = 0; i < _NSIG; ++i)
+		t->sighand->action[i].sa.sa_handler = SIG_IGN;
+
+	flush_signals(t);
+}
+
+/*
+ * Flush all handlers for a task.
+ */
+
+void
+flush_signal_handlers(struct task_struct *t, int force_default)
+{
+	int i;
+	struct k_sigaction *ka = &t->sighand->action[0];
+	for (i = _NSIG ; i != 0 ; i--) {
+		if (force_default || ka->sa.sa_handler != SIG_IGN)
+			ka->sa.sa_handler = SIG_DFL;
+		ka->sa.sa_flags = 0;
+		sigemptyset(&ka->sa.sa_mask);
+		ka++;
+	}
+}
+
+int unhandled_signal(struct task_struct *tsk, int sig)
+{
+	void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
+	if (is_global_init(tsk))
+		return 1;
+	if (handler != SIG_IGN && handler != SIG_DFL)
+		return 0;
+	/* if ptraced, let the tracer determine */
+	return !tsk->ptrace;
+}
+
+/*
+ * Notify the system that a driver wants to block all signals for this
+ * process, and wants to be notified if any signals at all were to be
+ * sent/acted upon.  If the notifier routine returns non-zero, then the
+ * signal will be acted upon after all.  If the notifier routine returns 0,
+ * then then signal will be blocked.  Only one block per process is
+ * allowed.  priv is a pointer to private data that the notifier routine
+ * can use to determine if the signal should be blocked or not.
+ */
+void
+block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&current->sighand->siglock, flags);
+	current->notifier_mask = mask;
+	current->notifier_data = priv;
+	current->notifier = notifier;
+	spin_unlock_irqrestore(&current->sighand->siglock, flags);
+}
+
+/* Notify the system that blocking has ended. */
+
+void
+unblock_all_signals(void)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&current->sighand->siglock, flags);
+	current->notifier = NULL;
+	current->notifier_data = NULL;
+	recalc_sigpending();
+	spin_unlock_irqrestore(&current->sighand->siglock, flags);
+}
+
+static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
+{
+	struct sigqueue *q, *first = NULL;
+
+	/*
+	 * Collect the siginfo appropriate to this signal.  Check if
+	 * there is another siginfo for the same signal.
+	*/
+	list_for_each_entry(q, &list->list, list) {
+		if (q->info.si_signo == sig) {
+			if (first)
+				goto still_pending;
+			first = q;
+		}
+	}
+
+	sigdelset(&list->signal, sig);
+
+	if (first) {
+still_pending:
+		list_del_init(&first->list);
+		copy_siginfo(info, &first->info);
+		__sigqueue_free(first);
+	} else {
+		/*
+		 * Ok, it wasn't in the queue.  This must be
+		 * a fast-pathed signal or we must have been
+		 * out of queue space.  So zero out the info.
+		 */
+		info->si_signo = sig;
+		info->si_errno = 0;
+		info->si_code = SI_USER;
+		info->si_pid = 0;
+		info->si_uid = 0;
+	}
+}
+
+static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
+			siginfo_t *info)
+{
+	int sig = next_signal(pending, mask);
+
+	if (sig) {
+		if (current->notifier) {
+			if (sigismember(current->notifier_mask, sig)) {
+				if (!(current->notifier)(current->notifier_data)) {
+					clear_thread_flag(TIF_SIGPENDING);
+					return 0;
+				}
+			}
+		}
+
+		collect_signal(sig, pending, info);
+	}
+
+	return sig;
+}
+
+/*
+ * Dequeue a signal and return the element to the caller, which is
+ * expected to free it.
+ *
+ * All callers have to hold the siglock.
+ */
+int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
+{
+	int signr;
+
+	/* We only dequeue private signals from ourselves, we don't let
+	 * signalfd steal them
+	 */
+	signr = __dequeue_signal(&tsk->pending, mask, info);
+	if (!signr) {
+		signr = __dequeue_signal(&tsk->signal->shared_pending,
+					 mask, info);
+		/*
+		 * itimer signal ?
+		 *
+		 * itimers are process shared and we restart periodic
+		 * itimers in the signal delivery path to prevent DoS
+		 * attacks in the high resolution timer case. This is
+		 * compliant with the old way of self-restarting
+		 * itimers, as the SIGALRM is a legacy signal and only
+		 * queued once. Changing the restart behaviour to
+		 * restart the timer in the signal dequeue path is
+		 * reducing the timer noise on heavy loaded !highres
+		 * systems too.
+		 */
+		if (unlikely(signr == SIGALRM)) {
+			struct hrtimer *tmr = &tsk->signal->real_timer;
+
+			if (!hrtimer_is_queued(tmr) &&
+			    tsk->signal->it_real_incr.tv64 != 0) {
+				hrtimer_forward(tmr, tmr->base->get_time(),
+						tsk->signal->it_real_incr);
+				hrtimer_restart(tmr);
+			}
+		}
+	}
+
+	recalc_sigpending();
+	if (!signr)
+		return 0;
+
+	if (unlikely(sig_kernel_stop(signr))) {
+		/*
+		 * Set a marker that we have dequeued a stop signal.  Our
+		 * caller might release the siglock and then the pending
+		 * stop signal it is about to process is no longer in the
+		 * pending bitmasks, but must still be cleared by a SIGCONT
+		 * (and overruled by a SIGKILL).  So those cases clear this
+		 * shared flag after we've set it.  Note that this flag may
+		 * remain set after the signal we return is ignored or
+		 * handled.  That doesn't matter because its only purpose
+		 * is to alert stop-signal processing code when another
+		 * processor has come along and cleared the flag.
+		 */
+		current->jobctl |= JOBCTL_STOP_DEQUEUED;
+	}
+	if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
+		/*
+		 * Release the siglock to ensure proper locking order
+		 * of timer locks outside of siglocks.  Note, we leave
+		 * irqs disabled here, since the posix-timers code is
+		 * about to disable them again anyway.
+		 */
+		spin_unlock(&tsk->sighand->siglock);
+		do_schedule_next_timer(info);
+		spin_lock(&tsk->sighand->siglock);
+	}
+	return signr;
+}
+
+/*
+ * Tell a process that it has a new active signal..
+ *
+ * NOTE! we rely on the previous spin_lock to
+ * lock interrupts for us! We can only be called with
+ * "siglock" held, and the local interrupt must
+ * have been disabled when that got acquired!
+ *
+ * No need to set need_resched since signal event passing
+ * goes through ->blocked
+ */
+void signal_wake_up(struct task_struct *t, int resume)
+{
+	unsigned int mask;
+
+	set_tsk_thread_flag(t, TIF_SIGPENDING);
+
+	/*
+	 * For SIGKILL, we want to wake it up in the stopped/traced/killable
+	 * case. We don't check t->state here because there is a race with it
+	 * executing another processor and just now entering stopped state.
+	 * By using wake_up_state, we ensure the process will wake up and
+	 * handle its death signal.
+	 */
+	mask = TASK_INTERRUPTIBLE;
+	if (resume)
+		mask |= TASK_WAKEKILL;
+	if (!wake_up_state(t, mask))
+		kick_process(t);
+}
+
+/*
+ * Remove signals in mask from the pending set and queue.
+ * Returns 1 if any signals were found.
+ *
+ * All callers must be holding the siglock.
+ *
+ * This version takes a sigset mask and looks at all signals,
+ * not just those in the first mask word.
+ */
+static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
+{
+	struct sigqueue *q, *n;
+	sigset_t m;
+
+	sigandsets(&m, mask, &s->signal);
+	if (sigisemptyset(&m))
+		return 0;
+
+	sigandnsets(&s->signal, &s->signal, mask);
+	list_for_each_entry_safe(q, n, &s->list, list) {
+		if (sigismember(mask, q->info.si_signo)) {
+			list_del_init(&q->list);
+			__sigqueue_free(q);
+		}
+	}
+	return 1;
+}
+/*
+ * Remove signals in mask from the pending set and queue.
+ * Returns 1 if any signals were found.
+ *
+ * All callers must be holding the siglock.
+ */
+static int rm_from_queue(unsigned long mask, struct sigpending *s)
+{
+	struct sigqueue *q, *n;
+
+	if (!sigtestsetmask(&s->signal, mask))
+		return 0;
+
+	sigdelsetmask(&s->signal, mask);
+	list_for_each_entry_safe(q, n, &s->list, list) {
+		if (q->info.si_signo < SIGRTMIN &&
+		    (mask & sigmask(q->info.si_signo))) {
+			list_del_init(&q->list);
+			__sigqueue_free(q);
+		}
+	}
+	return 1;
+}
+
+static inline int is_si_special(const struct siginfo *info)
+{
+	return info <= SEND_SIG_FORCED;
+}
+
+static inline bool si_fromuser(const struct siginfo *info)
+{
+	return info == SEND_SIG_NOINFO ||
+		(!is_si_special(info) && SI_FROMUSER(info));
+}
+
+/*
+ * called with RCU read lock from check_kill_permission()
+ */
+static int kill_ok_by_cred(struct task_struct *t)
+{
+	const struct cred *cred = current_cred();
+	const struct cred *tcred = __task_cred(t);
+
+	if (cred->user->user_ns == tcred->user->user_ns &&
+	    (cred->euid == tcred->suid ||
+	     cred->euid == tcred->uid ||
+	     cred->uid  == tcred->suid ||
+	     cred->uid  == tcred->uid))
+		return 1;
+
+	if (ns_capable(tcred->user->user_ns, CAP_KILL))
+		return 1;
+
+	return 0;
+}
+
+/*
+ * Bad permissions for sending the signal
+ * - the caller must hold the RCU read lock
+ */
+static int check_kill_permission(int sig, struct siginfo *info,
+				 struct task_struct *t)
+{
+	struct pid *sid;
+	int error;
+
+	if (!valid_signal(sig))
+		return -EINVAL;
+
+	if (!si_fromuser(info))
+		return 0;
+
+	error = audit_signal_info(sig, t); /* Let audit system see the signal */
+	if (error)
+		return error;
+
+	if (!same_thread_group(current, t) &&
+	    !kill_ok_by_cred(t)) {
+		switch (sig) {
+		case SIGCONT:
+			sid = task_session(t);
+			/*
+			 * We don't return the error if sid == NULL. The
+			 * task was unhashed, the caller must notice this.
+			 */
+			if (!sid || sid == task_session(current))
+				break;
+		default:
+			return -EPERM;
+		}
+	}
+
+	return security_task_kill(t, info, sig, 0);
+}
+
+/**
+ * ptrace_trap_notify - schedule trap to notify ptracer
+ * @t: tracee wanting to notify tracer
+ *
+ * This function schedules sticky ptrace trap which is cleared on the next
+ * TRAP_STOP to notify ptracer of an event.  @t must have been seized by
+ * ptracer.
+ *
+ * If @t is running, STOP trap will be taken.  If trapped for STOP and
+ * ptracer is listening for events, tracee is woken up so that it can
+ * re-trap for the new event.  If trapped otherwise, STOP trap will be
+ * eventually taken without returning to userland after the existing traps
+ * are finished by PTRACE_CONT.
+ *
+ * CONTEXT:
+ * Must be called with @task->sighand->siglock held.
+ */
+static void ptrace_trap_notify(struct task_struct *t)
+{
+	WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
+	assert_spin_locked(&t->sighand->siglock);
+
+	task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
+	signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
+}
+
+/*
+ * Handle magic process-wide effects of stop/continue signals. Unlike
+ * the signal actions, these happen immediately at signal-generation
+ * time regardless of blocking, ignoring, or handling.  This does the
+ * actual continuing for SIGCONT, but not the actual stopping for stop
+ * signals. The process stop is done as a signal action for SIG_DFL.
+ *
+ * Returns true if the signal should be actually delivered, otherwise
+ * it should be dropped.
+ */
+static int prepare_signal(int sig, struct task_struct *p, bool force)
+{
+	struct signal_struct *signal = p->signal;
+	struct task_struct *t;
+
+	if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
+		/*
+		 * The process is in the middle of dying, nothing to do.
+		 */
+	} else if (sig_kernel_stop(sig)) {
+		/*
+		 * This is a stop signal.  Remove SIGCONT from all queues.
+		 */
+		rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
+		t = p;
+		do {
+			rm_from_queue(sigmask(SIGCONT), &t->pending);
+		} while_each_thread(p, t);
+	} else if (sig == SIGCONT) {
+		unsigned int why;
+		/*
+		 * Remove all stop signals from all queues, wake all threads.
+		 */
+		rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
+		t = p;
+		do {
+			task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
+			rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
+			if (likely(!(t->ptrace & PT_SEIZED)))
+				wake_up_state(t, __TASK_STOPPED);
+			else
+				ptrace_trap_notify(t);
+		} while_each_thread(p, t);
+
+		/*
+		 * Notify the parent with CLD_CONTINUED if we were stopped.
+		 *
+		 * If we were in the middle of a group stop, we pretend it
+		 * was already finished, and then continued. Since SIGCHLD
+		 * doesn't queue we report only CLD_STOPPED, as if the next
+		 * CLD_CONTINUED was dropped.
+		 */
+		why = 0;
+		if (signal->flags & SIGNAL_STOP_STOPPED)
+			why |= SIGNAL_CLD_CONTINUED;
+		else if (signal->group_stop_count)
+			why |= SIGNAL_CLD_STOPPED;
+
+		if (why) {
+			/*
+			 * The first thread which returns from do_signal_stop()
+			 * will take ->siglock, notice SIGNAL_CLD_MASK, and
+			 * notify its parent. See get_signal_to_deliver().
+			 */
+			signal->flags = why | SIGNAL_STOP_CONTINUED;
+			signal->group_stop_count = 0;
+			signal->group_exit_code = 0;
+		}
+	}
+
+	return !sig_ignored(p, sig, force);
+}
+
+/*
+ * Test if P wants to take SIG.  After we've checked all threads with this,
+ * it's equivalent to finding no threads not blocking SIG.  Any threads not
+ * blocking SIG were ruled out because they are not running and already
+ * have pending signals.  Such threads will dequeue from the shared queue
+ * as soon as they're available, so putting the signal on the shared queue
+ * will be equivalent to sending it to one such thread.
+ */
+static inline int wants_signal(int sig, struct task_struct *p)
+{
+	if (sigismember(&p->blocked, sig))
+		return 0;
+	if (p->flags & PF_EXITING)
+		return 0;
+	if (sig == SIGKILL)
+		return 1;
+	if (task_is_stopped_or_traced(p))
+		return 0;
+	return task_curr(p) || !signal_pending(p);
+}
+
+static void complete_signal(int sig, struct task_struct *p, int group)
+{
+	struct signal_struct *signal = p->signal;
+	struct task_struct *t;
+
+	/*
+	 * Now find a thread we can wake up to take the signal off the queue.
+	 *
+	 * If the main thread wants the signal, it gets first crack.
+	 * Probably the least surprising to the average bear.
+	 */
+	if (wants_signal(sig, p))
+		t = p;
+	else if (!group || thread_group_empty(p))
+		/*
+		 * There is just one thread and it does not need to be woken.
+		 * It will dequeue unblocked signals before it runs again.
+		 */
+		return;
+	else {
+		/*
+		 * Otherwise try to find a suitable thread.
+		 */
+		t = signal->curr_target;
+		while (!wants_signal(sig, t)) {
+			t = next_thread(t);
+			if (t == signal->curr_target)
+				/*
+				 * No thread needs to be woken.
+				 * Any eligible threads will see
+				 * the signal in the queue soon.
+				 */
+				return;
+		}
+		signal->curr_target = t;
+	}
+
+	/*
+	 * Found a killable thread.  If the signal will be fatal,
+	 * then start taking the whole group down immediately.
+	 */
+	if (sig_fatal(p, sig) &&
+	    !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
+	    !sigismember(&t->real_blocked, sig) &&
+	    (sig == SIGKILL || !t->ptrace)) {
+		/*
+		 * This signal will be fatal to the whole group.
+		 */
+		if (!sig_kernel_coredump(sig)) {
+			/*
+			 * Start a group exit and wake everybody up.
+			 * This way we don't have other threads
+			 * running and doing things after a slower
+			 * thread has the fatal signal pending.
+			 */
+			signal->flags = SIGNAL_GROUP_EXIT;
+			signal->group_exit_code = sig;
+			signal->group_stop_count = 0;
+			t = p;
+			do {
+				task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
+				sigaddset(&t->pending.signal, SIGKILL);
+				signal_wake_up(t, 1);
+			} while_each_thread(p, t);
+			return;
+		}
+	}
+
+	/*
+	 * The signal is already in the shared-pending queue.
+	 * Tell the chosen thread to wake up and dequeue it.
+	 */
+	signal_wake_up(t, sig == SIGKILL);
+	return;
+}
+
+static inline int legacy_queue(struct sigpending *signals, int sig)
+{
+	return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
+}
+
+/*
+ * map the uid in struct cred into user namespace *ns
+ */
+static inline uid_t map_cred_ns(const struct cred *cred,
+				struct user_namespace *ns)
+{
+	return user_ns_map_uid(ns, cred, cred->uid);
+}
+
+#ifdef CONFIG_USER_NS
+static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
+{
+	if (current_user_ns() == task_cred_xxx(t, user_ns))
+		return;
+
+	if (SI_FROMKERNEL(info))
+		return;
+
+	info->si_uid = user_ns_map_uid(task_cred_xxx(t, user_ns),
+					current_cred(), info->si_uid);
+}
+#else
+static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
+{
+	return;
+}
+#endif
+
+static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
+			int group, int from_ancestor_ns)
+{
+	struct sigpending *pending;
+	struct sigqueue *q;
+	int override_rlimit;
+	int ret = 0, result;
+
+	assert_spin_locked(&t->sighand->siglock);
+
+	result = TRACE_SIGNAL_IGNORED;
+	if (!prepare_signal(sig, t,
+			from_ancestor_ns || (info == SEND_SIG_FORCED)))
+		goto ret;
+
+	pending = group ? &t->signal->shared_pending : &t->pending;
+	/*
+	 * Short-circuit ignored signals and support queuing
+	 * exactly one non-rt signal, so that we can get more
+	 * detailed information about the cause of the signal.
+	 */
+	result = TRACE_SIGNAL_ALREADY_PENDING;
+	if (legacy_queue(pending, sig))
+		goto ret;
+
+	result = TRACE_SIGNAL_DELIVERED;
+	/*
+	 * fast-pathed signals for kernel-internal things like SIGSTOP
+	 * or SIGKILL.
+	 */
+	if (info == SEND_SIG_FORCED)
+		goto out_set;
+
+	/*
+	 * Real-time signals must be queued if sent by sigqueue, or
+	 * some other real-time mechanism.  It is implementation
+	 * defined whether kill() does so.  We attempt to do so, on
+	 * the principle of least surprise, but since kill is not
+	 * allowed to fail with EAGAIN when low on memory we just
+	 * make sure at least one signal gets delivered and don't
+	 * pass on the info struct.
+	 */
+	if (sig < SIGRTMIN)
+		override_rlimit = (is_si_special(info) || info->si_code >= 0);
+	else
+		override_rlimit = 0;
+
+	q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
+		override_rlimit);
+	if (q) {
+		list_add_tail(&q->list, &pending->list);
+		switch ((unsigned long) info) {
+		case (unsigned long) SEND_SIG_NOINFO:
+			q->info.si_signo = sig;
+			q->info.si_errno = 0;
+			q->info.si_code = SI_USER;
+			q->info.si_pid = task_tgid_nr_ns(current,
+							task_active_pid_ns(t));
+			q->info.si_uid = current_uid();
+			break;
+		case (unsigned long) SEND_SIG_PRIV:
+			q->info.si_signo = sig;
+			q->info.si_errno = 0;
+			q->info.si_code = SI_KERNEL;
+			q->info.si_pid = 0;
+			q->info.si_uid = 0;
+			break;
+		default:
+			copy_siginfo(&q->info, info);
+			if (from_ancestor_ns)
+				q->info.si_pid = 0;
+			break;
+		}
+
+		userns_fixup_signal_uid(&q->info, t);
+
+	} else if (!is_si_special(info)) {
+		if (sig >= SIGRTMIN && info->si_code != SI_USER) {
+			/*
+			 * Queue overflow, abort.  We may abort if the
+			 * signal was rt and sent by user using something
+			 * other than kill().
+			 */
+			result = TRACE_SIGNAL_OVERFLOW_FAIL;
+			ret = -EAGAIN;
+			goto ret;
+		} else {
+			/*
+			 * This is a silent loss of information.  We still
+			 * send the signal, but the *info bits are lost.
+			 */
+			result = TRACE_SIGNAL_LOSE_INFO;
+		}
+	}
+
+out_set:
+	signalfd_notify(t, sig);
+	sigaddset(&pending->signal, sig);
+	complete_signal(sig, t, group);
+ret:
+	trace_signal_generate(sig, info, t, group, result);
+	return ret;
+}
+
+static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
+			int group)
+{
+	int from_ancestor_ns = 0;
+
+#ifdef CONFIG_PID_NS
+	from_ancestor_ns = si_fromuser(info) &&
+			   !task_pid_nr_ns(current, task_active_pid_ns(t));
+#endif
+
+	return __send_signal(sig, info, t, group, from_ancestor_ns);
+}
+
+static void print_fatal_signal(struct pt_regs *regs, int signr)
+{
+	printk("%s/%d: potentially unexpected fatal signal %d.\n",
+		current->comm, task_pid_nr(current), signr);
+
+#if defined(__i386__) && !defined(__arch_um__)
+	printk("code at %08lx: ", regs->ip);
+	{
+		int i;
+		for (i = 0; i < 16; i++) {
+			unsigned char insn;
+
+			if (get_user(insn, (unsigned char *)(regs->ip + i)))
+				break;
+			printk("%02x ", insn);
+		}
+	}
+#endif
+	printk("\n");
+	preempt_disable();
+	show_regs(regs);
+	preempt_enable();
+}
+
+static int __init setup_print_fatal_signals(char *str)
+{
+	get_option (&str, &print_fatal_signals);
+
+	return 1;
+}
+
+__setup("print-fatal-signals=", setup_print_fatal_signals);
+
+int
+__group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
+{
+	return send_signal(sig, info, p, 1);
+}
+
+static int
+specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
+{
+	return send_signal(sig, info, t, 0);
+}
+
+int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
+			bool group)
+{
+	unsigned long flags;
+	int ret = -ESRCH;
+
+	if (lock_task_sighand(p, &flags)) {
+		ret = send_signal(sig, info, p, group);
+		unlock_task_sighand(p, &flags);
+	}
+
+	return ret;
+}
+
+/*
+ * Force a signal that the process can't ignore: if necessary
+ * we unblock the signal and change any SIG_IGN to SIG_DFL.
+ *
+ * Note: If we unblock the signal, we always reset it to SIG_DFL,
+ * since we do not want to have a signal handler that was blocked
+ * be invoked when user space had explicitly blocked it.
+ *
+ * We don't want to have recursive SIGSEGV's etc, for example,
+ * that is why we also clear SIGNAL_UNKILLABLE.
+ */
+int
+force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
+{
+	unsigned long int flags;
+	int ret, blocked, ignored;
+	struct k_sigaction *action;
+
+	spin_lock_irqsave(&t->sighand->siglock, flags);
+	action = &t->sighand->action[sig-1];
+	ignored = action->sa.sa_handler == SIG_IGN;
+	blocked = sigismember(&t->blocked, sig);
+	if (blocked || ignored) {
+		action->sa.sa_handler = SIG_DFL;
+		if (blocked) {
+			sigdelset(&t->blocked, sig);
+			recalc_sigpending_and_wake(t);
+		}
+	}
+	if (action->sa.sa_handler == SIG_DFL)
+		t->signal->flags &= ~SIGNAL_UNKILLABLE;
+	ret = specific_send_sig_info(sig, info, t);
+	spin_unlock_irqrestore(&t->sighand->siglock, flags);
+
+	return ret;
+}
+
+/*
+ * Nuke all other threads in the group.
+ */
+int zap_other_threads(struct task_struct *p)
+{
+	struct task_struct *t = p;
+	int count = 0;
+
+	p->signal->group_stop_count = 0;
+
+	while_each_thread(p, t) {
+		task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
+		count++;
+
+		/* Don't bother with already dead threads */
+		if (t->exit_state)
+			continue;
+		sigaddset(&t->pending.signal, SIGKILL);
+		signal_wake_up(t, 1);
+	}
+
+	return count;
+}
+
+struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
+					   unsigned long *flags)
+{
+	struct sighand_struct *sighand;
+
+	for (;;) {
+		local_irq_save(*flags);
+		rcu_read_lock();
+		sighand = rcu_dereference(tsk->sighand);
+		if (unlikely(sighand == NULL)) {
+			rcu_read_unlock();
+			local_irq_restore(*flags);
+			break;
+		}
+
+		spin_lock(&sighand->siglock);
+		if (likely(sighand == tsk->sighand)) {
+			rcu_read_unlock();
+			break;
+		}
+		spin_unlock(&sighand->siglock);
+		rcu_read_unlock();
+		local_irq_restore(*flags);
+	}
+
+	return sighand;
+}
+
+/*
+ * send signal info to all the members of a group
+ */
+int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
+{
+	int ret;
+
+	rcu_read_lock();
+	ret = check_kill_permission(sig, info, p);
+	rcu_read_unlock();
+
+	if (!ret && sig)
+		ret = do_send_sig_info(sig, info, p, true);
+
+	return ret;
+}
+
+/*
+ * __kill_pgrp_info() sends a signal to a process group: this is what the tty
+ * control characters do (^C, ^Z etc)
+ * - the caller must hold at least a readlock on tasklist_lock
+ */
+int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
+{
+	struct task_struct *p = NULL;
+	int retval, success;
+
+	success = 0;
+	retval = -ESRCH;
+	do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
+		int err = group_send_sig_info(sig, info, p);
+		success |= !err;
+		retval = err;
+	} while_each_pid_task(pgrp, PIDTYPE_PGID, p);
+	return success ? 0 : retval;
+}
+
+int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
+{
+	int error = -ESRCH;
+	struct task_struct *p;
+
+	rcu_read_lock();
+retry:
+	p = pid_task(pid, PIDTYPE_PID);
+	if (p) {
+		error = group_send_sig_info(sig, info, p);
+		if (unlikely(error == -ESRCH))
+			/*
+			 * The task was unhashed in between, try again.
+			 * If it is dead, pid_task() will return NULL,
+			 * if we race with de_thread() it will find the
+			 * new leader.
+			 */
+			goto retry;
+	}
+	rcu_read_unlock();
+
+	return error;
+}
+
+int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
+{
+	int error;
+	rcu_read_lock();
+	error = kill_pid_info(sig, info, find_vpid(pid));
+	rcu_read_unlock();
+	return error;
+}
+
+static int kill_as_cred_perm(const struct cred *cred,
+			     struct task_struct *target)
+{
+	const struct cred *pcred = __task_cred(target);
+	if (cred->user_ns != pcred->user_ns)
+		return 0;
+	if (cred->euid != pcred->suid && cred->euid != pcred->uid &&
+	    cred->uid  != pcred->suid && cred->uid  != pcred->uid)
+		return 0;
+	return 1;
+}
+
+/* like kill_pid_info(), but doesn't use uid/euid of "current" */
+int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
+			 const struct cred *cred, u32 secid)
+{
+	int ret = -EINVAL;
+	struct task_struct *p;
+	unsigned long flags;
+
+	if (!valid_signal(sig))
+		return ret;
+
+	rcu_read_lock();
+	p = pid_task(pid, PIDTYPE_PID);
+	if (!p) {
+		ret = -ESRCH;
+		goto out_unlock;
+	}
+	if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
+		ret = -EPERM;
+		goto out_unlock;
+	}
+	ret = security_task_kill(p, info, sig, secid);
+	if (ret)
+		goto out_unlock;
+
+	if (sig) {
+		if (lock_task_sighand(p, &flags)) {
+			ret = __send_signal(sig, info, p, 1, 0);
+			unlock_task_sighand(p, &flags);
+		} else
+			ret = -ESRCH;
+	}
+out_unlock:
+	rcu_read_unlock();
+	return ret;
+}
+EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
+
+/*
+ * kill_something_info() interprets pid in interesting ways just like kill(2).
+ *
+ * POSIX specifies that kill(-1,sig) is unspecified, but what we have
+ * is probably wrong.  Should make it like BSD or SYSV.
+ */
+
+static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
+{
+	int ret;
+
+	if (pid > 0) {
+		rcu_read_lock();
+		ret = kill_pid_info(sig, info, find_vpid(pid));
+		rcu_read_unlock();
+		return ret;
+	}
+
+	read_lock(&tasklist_lock);
+	if (pid != -1) {
+		ret = __kill_pgrp_info(sig, info,
+				pid ? find_vpid(-pid) : task_pgrp(current));
+	} else {
+		int retval = 0, count = 0;
+		struct task_struct * p;
+
+		for_each_process(p) {
+			if (task_pid_vnr(p) > 1 &&
+					!same_thread_group(p, current)) {
+				int err = group_send_sig_info(sig, info, p);
+				++count;
+				if (err != -EPERM)
+					retval = err;
+			}
+		}
+		ret = count ? retval : -ESRCH;
+	}
+	read_unlock(&tasklist_lock);
+
+	return ret;
+}
+
+/*
+ * These are for backward compatibility with the rest of the kernel source.
+ */
+
+int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
+{
+	/*
+	 * Make sure legacy kernel users don't send in bad values
+	 * (normal paths check this in check_kill_permission).
+	 */
+	if (!valid_signal(sig))
+		return -EINVAL;
+
+	return do_send_sig_info(sig, info, p, false);
+}
+
+#define __si_special(priv) \
+	((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
+
+int
+send_sig(int sig, struct task_struct *p, int priv)
+{
+	return send_sig_info(sig, __si_special(priv), p);
+}
+
+void
+force_sig(int sig, struct task_struct *p)
+{
+	force_sig_info(sig, SEND_SIG_PRIV, p);
+}
+
+/*
+ * When things go south during signal handling, we
+ * will force a SIGSEGV. And if the signal that caused
+ * the problem was already a SIGSEGV, we'll want to
+ * make sure we don't even try to deliver the signal..
+ */
+int
+force_sigsegv(int sig, struct task_struct *p)
+{
+	if (sig == SIGSEGV) {
+		unsigned long flags;
+		spin_lock_irqsave(&p->sighand->siglock, flags);
+		p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
+		spin_unlock_irqrestore(&p->sighand->siglock, flags);
+	}
+	force_sig(SIGSEGV, p);
+	return 0;
+}
+
+int kill_pgrp(struct pid *pid, int sig, int priv)
+{
+	int ret;
+
+	read_lock(&tasklist_lock);
+	ret = __kill_pgrp_info(sig, __si_special(priv), pid);
+	read_unlock(&tasklist_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(kill_pgrp);
+
+int kill_pid(struct pid *pid, int sig, int priv)
+{
+	return kill_pid_info(sig, __si_special(priv), pid);
+}
+EXPORT_SYMBOL(kill_pid);
+
+/*
+ * These functions support sending signals using preallocated sigqueue
+ * structures.  This is needed "because realtime applications cannot
+ * afford to lose notifications of asynchronous events, like timer
+ * expirations or I/O completions".  In the case of POSIX Timers
+ * we allocate the sigqueue structure from the timer_create.  If this
+ * allocation fails we are able to report the failure to the application
+ * with an EAGAIN error.
+ */
+struct sigqueue *sigqueue_alloc(void)
+{
+	struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
+
+	if (q)
+		q->flags |= SIGQUEUE_PREALLOC;
+
+	return q;
+}
+
+void sigqueue_free(struct sigqueue *q)
+{
+	unsigned long flags;
+	spinlock_t *lock = &current->sighand->siglock;
+
+	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
+	/*
+	 * We must hold ->siglock while testing q->list
+	 * to serialize with collect_signal() or with
+	 * __exit_signal()->flush_sigqueue().
+	 */
+	spin_lock_irqsave(lock, flags);
+	q->flags &= ~SIGQUEUE_PREALLOC;
+	/*
+	 * If it is queued it will be freed when dequeued,
+	 * like the "regular" sigqueue.
+	 */
+	if (!list_empty(&q->list))
+		q = NULL;
+	spin_unlock_irqrestore(lock, flags);
+
+	if (q)
+		__sigqueue_free(q);
+}
+
+int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
+{
+	int sig = q->info.si_signo;
+	struct sigpending *pending;
+	unsigned long flags;
+	int ret, result;
+
+	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
+
+	ret = -1;
+	if (!likely(lock_task_sighand(t, &flags)))
+		goto ret;
+
+	ret = 1; /* the signal is ignored */
+	result = TRACE_SIGNAL_IGNORED;
+	if (!prepare_signal(sig, t, false))
+		goto out;
+
+	ret = 0;
+	if (unlikely(!list_empty(&q->list))) {
+		/*
+		 * If an SI_TIMER entry is already queue just increment
+		 * the overrun count.
+		 */
+		BUG_ON(q->info.si_code != SI_TIMER);
+		q->info.si_overrun++;
+		result = TRACE_SIGNAL_ALREADY_PENDING;
+		goto out;
+	}
+	q->info.si_overrun = 0;
+
+	signalfd_notify(t, sig);
+	pending = group ? &t->signal->shared_pending : &t->pending;
+	list_add_tail(&q->list, &pending->list);
+	sigaddset(&pending->signal, sig);
+	complete_signal(sig, t, group);
+	result = TRACE_SIGNAL_DELIVERED;
+out:
+	trace_signal_generate(sig, &q->info, t, group, result);
+	unlock_task_sighand(t, &flags);
+ret:
+	return ret;
+}
+
+/*
+ * Let a parent know about the death of a child.
+ * For a stopped/continued status change, use do_notify_parent_cldstop instead.
+ *
+ * Returns true if our parent ignored us and so we've switched to
+ * self-reaping.
+ */
+bool do_notify_parent(struct task_struct *tsk, int sig)
+{
+	struct siginfo info;
+	unsigned long flags;
+	struct sighand_struct *psig;
+	bool autoreap = false;
+
+	BUG_ON(sig == -1);
+
+ 	/* do_notify_parent_cldstop should have been called instead.  */
+ 	BUG_ON(task_is_stopped_or_traced(tsk));
+
+	BUG_ON(!tsk->ptrace &&
+	       (tsk->group_leader != tsk || !thread_group_empty(tsk)));
+
+	if (sig != SIGCHLD) {
+		/*
+		 * This is only possible if parent == real_parent.
+		 * Check if it has changed security domain.
+		 */
+		if (tsk->parent_exec_id != tsk->parent->self_exec_id)
+			sig = SIGCHLD;
+	}
+
+	info.si_signo = sig;
+	info.si_errno = 0;
+	/*
+	 * we are under tasklist_lock here so our parent is tied to
+	 * us and cannot exit and release its namespace.
+	 *
+	 * the only it can is to switch its nsproxy with sys_unshare,
+	 * bu uncharing pid namespaces is not allowed, so we'll always
+	 * see relevant namespace
+	 *
+	 * write_lock() currently calls preempt_disable() which is the
+	 * same as rcu_read_lock(), but according to Oleg, this is not
+	 * correct to rely on this
+	 */
+	rcu_read_lock();
+	info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
+	info.si_uid = map_cred_ns(__task_cred(tsk),
+			task_cred_xxx(tsk->parent, user_ns));
+	rcu_read_unlock();
+
+	info.si_utime = cputime_to_clock_t(tsk->utime + tsk->signal->utime);
+	info.si_stime = cputime_to_clock_t(tsk->stime + tsk->signal->stime);
+
+	info.si_status = tsk->exit_code & 0x7f;
+	if (tsk->exit_code & 0x80)
+		info.si_code = CLD_DUMPED;
+	else if (tsk->exit_code & 0x7f)
+		info.si_code = CLD_KILLED;
+	else {
+		info.si_code = CLD_EXITED;
+		info.si_status = tsk->exit_code >> 8;
+	}
+
+	psig = tsk->parent->sighand;
+	spin_lock_irqsave(&psig->siglock, flags);
+	if (!tsk->ptrace && sig == SIGCHLD &&
+	    (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
+	     (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
+		/*
+		 * We are exiting and our parent doesn't care.  POSIX.1
+		 * defines special semantics for setting SIGCHLD to SIG_IGN
+		 * or setting the SA_NOCLDWAIT flag: we should be reaped
+		 * automatically and not left for our parent's wait4 call.
+		 * Rather than having the parent do it as a magic kind of
+		 * signal handler, we just set this to tell do_exit that we
+		 * can be cleaned up without becoming a zombie.  Note that
+		 * we still call __wake_up_parent in this case, because a
+		 * blocked sys_wait4 might now return -ECHILD.
+		 *
+		 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
+		 * is implementation-defined: we do (if you don't want
+		 * it, just use SIG_IGN instead).
+		 */
+		autoreap = true;
+		if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
+			sig = 0;
+	}
+	if (valid_signal(sig) && sig)
+		__group_send_sig_info(sig, &info, tsk->parent);
+	__wake_up_parent(tsk, tsk->parent);
+	spin_unlock_irqrestore(&psig->siglock, flags);
+
+	return autoreap;
+}
+
+/**
+ * do_notify_parent_cldstop - notify parent of stopped/continued state change
+ * @tsk: task reporting the state change
+ * @for_ptracer: the notification is for ptracer
+ * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
+ *
+ * Notify @tsk's parent that the stopped/continued state has changed.  If
+ * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
+ * If %true, @tsk reports to @tsk->parent which should be the ptracer.
+ *
+ * CONTEXT:
+ * Must be called with tasklist_lock at least read locked.
+ */
+static void do_notify_parent_cldstop(struct task_struct *tsk,
+				     bool for_ptracer, int why)
+{
+	struct siginfo info;
+	unsigned long flags;
+	struct task_struct *parent;
+	struct sighand_struct *sighand;
+
+	if (for_ptracer) {
+		parent = tsk->parent;
+	} else {
+		tsk = tsk->group_leader;
+		parent = tsk->real_parent;
+	}
+
+	info.si_signo = SIGCHLD;
+	info.si_errno = 0;
+	/*
+	 * see comment in do_notify_parent() about the following 4 lines
+	 */
+	rcu_read_lock();
+	info.si_pid = task_pid_nr_ns(tsk, parent->nsproxy->pid_ns);
+	info.si_uid = map_cred_ns(__task_cred(tsk),
+			task_cred_xxx(parent, user_ns));
+	rcu_read_unlock();
+
+	info.si_utime = cputime_to_clock_t(tsk->utime);
+	info.si_stime = cputime_to_clock_t(tsk->stime);
+
+ 	info.si_code = why;
+ 	switch (why) {
+ 	case CLD_CONTINUED:
+ 		info.si_status = SIGCONT;
+ 		break;
+ 	case CLD_STOPPED:
+ 		info.si_status = tsk->signal->group_exit_code & 0x7f;
+ 		break;
+ 	case CLD_TRAPPED:
+ 		info.si_status = tsk->exit_code & 0x7f;
+ 		break;
+ 	default:
+ 		BUG();
+ 	}
+
+	sighand = parent->sighand;
+	spin_lock_irqsave(&sighand->siglock, flags);
+	if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
+	    !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
+		__group_send_sig_info(SIGCHLD, &info, parent);
+	/*
+	 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
+	 */
+	__wake_up_parent(tsk, parent);
+	spin_unlock_irqrestore(&sighand->siglock, flags);
+}
+
+static inline int may_ptrace_stop(void)
+{
+	if (!likely(current->ptrace))
+		return 0;
+	/*
+	 * Are we in the middle of do_coredump?
+	 * If so and our tracer is also part of the coredump stopping
+	 * is a deadlock situation, and pointless because our tracer
+	 * is dead so don't allow us to stop.
+	 * If SIGKILL was already sent before the caller unlocked
+	 * ->siglock we must see ->core_state != NULL. Otherwise it
+	 * is safe to enter schedule().
+	 */
+	if (unlikely(current->mm->core_state) &&
+	    unlikely(current->mm == current->parent->mm))
+		return 0;
+
+	return 1;
+}
+
+/*
+ * Return non-zero if there is a SIGKILL that should be waking us up.
+ * Called with the siglock held.
+ */
+static int sigkill_pending(struct task_struct *tsk)
+{
+	return	sigismember(&tsk->pending.signal, SIGKILL) ||
+		sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
+}
+
+/*
+ * This must be called with current->sighand->siglock held.
+ *
+ * This should be the path for all ptrace stops.
+ * We always set current->last_siginfo while stopped here.
+ * That makes it a way to test a stopped process for
+ * being ptrace-stopped vs being job-control-stopped.
+ *
+ * If we actually decide not to stop at all because the tracer
+ * is gone, we keep current->exit_code unless clear_code.
+ */
+static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
+	__releases(&current->sighand->siglock)
+	__acquires(&current->sighand->siglock)
+{
+	bool gstop_done = false;
+
+	if (arch_ptrace_stop_needed(exit_code, info)) {
+		/*
+		 * The arch code has something special to do before a
+		 * ptrace stop.  This is allowed to block, e.g. for faults
+		 * on user stack pages.  We can't keep the siglock while
+		 * calling arch_ptrace_stop, so we must release it now.
+		 * To preserve proper semantics, we must do this before
+		 * any signal bookkeeping like checking group_stop_count.
+		 * Meanwhile, a SIGKILL could come in before we retake the
+		 * siglock.  That must prevent us from sleeping in TASK_TRACED.
+		 * So after regaining the lock, we must check for SIGKILL.
+		 */
+		spin_unlock_irq(&current->sighand->siglock);
+		arch_ptrace_stop(exit_code, info);
+		spin_lock_irq(&current->sighand->siglock);
+		if (sigkill_pending(current))
+			return;
+	}
+
+	/*
+	 * We're committing to trapping.  TRACED should be visible before
+	 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
+	 * Also, transition to TRACED and updates to ->jobctl should be
+	 * atomic with respect to siglock and should be done after the arch
+	 * hook as siglock is released and regrabbed across it.
+	 */
+	set_current_state(TASK_TRACED);
+
+	current->last_siginfo = info;
+	current->exit_code = exit_code;
+
+	/*
+	 * If @why is CLD_STOPPED, we're trapping to participate in a group
+	 * stop.  Do the bookkeeping.  Note that if SIGCONT was delievered
+	 * across siglock relocks since INTERRUPT was scheduled, PENDING
+	 * could be clear now.  We act as if SIGCONT is received after
+	 * TASK_TRACED is entered - ignore it.
+	 */
+	if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
+		gstop_done = task_participate_group_stop(current);
+
+	/* any trap clears pending STOP trap, STOP trap clears NOTIFY */
+	task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
+	if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
+		task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
+
+	/* entering a trap, clear TRAPPING */
+	task_clear_jobctl_trapping(current);
+
+	spin_unlock_irq(&current->sighand->siglock);
+	read_lock(&tasklist_lock);
+	if (may_ptrace_stop()) {
+		/*
+		 * Notify parents of the stop.
+		 *
+		 * While ptraced, there are two parents - the ptracer and
+		 * the real_parent of the group_leader.  The ptracer should
+		 * know about every stop while the real parent is only
+		 * interested in the completion of group stop.  The states
+		 * for the two don't interact with each other.  Notify
+		 * separately unless they're gonna be duplicates.
+		 */
+		do_notify_parent_cldstop(current, true, why);
+		if (gstop_done && ptrace_reparented(current))
+			do_notify_parent_cldstop(current, false, why);
+
+		/*
+		 * Don't want to allow preemption here, because
+		 * sys_ptrace() needs this task to be inactive.
+		 *
+		 * XXX: implement read_unlock_no_resched().
+		 */
+		preempt_disable();
+		read_unlock(&tasklist_lock);
+		preempt_enable_no_resched();
+		schedule();
+	} else {
+		/*
+		 * By the time we got the lock, our tracer went away.
+		 * Don't drop the lock yet, another tracer may come.
+		 *
+		 * If @gstop_done, the ptracer went away between group stop
+		 * completion and here.  During detach, it would have set
+		 * JOBCTL_STOP_PENDING on us and we'll re-enter
+		 * TASK_STOPPED in do_signal_stop() on return, so notifying
+		 * the real parent of the group stop completion is enough.
+		 */
+		if (gstop_done)
+			do_notify_parent_cldstop(current, false, why);
+
+		__set_current_state(TASK_RUNNING);
+		if (clear_code)
+			current->exit_code = 0;
+		read_unlock(&tasklist_lock);
+	}
+
+	/*
+	 * While in TASK_TRACED, we were considered "frozen enough".
+	 * Now that we woke up, it's crucial if we're supposed to be
+	 * frozen that we freeze now before running anything substantial.
+	 */
+	try_to_freeze();
+
+	/*
+	 * We are back.  Now reacquire the siglock before touching
+	 * last_siginfo, so that we are sure to have synchronized with
+	 * any signal-sending on another CPU that wants to examine it.
+	 */
+	spin_lock_irq(&current->sighand->siglock);
+	current->last_siginfo = NULL;
+
+	/* LISTENING can be set only during STOP traps, clear it */
+	current->jobctl &= ~JOBCTL_LISTENING;
+
+	/*
+	 * Queued signals ignored us while we were stopped for tracing.
+	 * So check for any that we should take before resuming user mode.
+	 * This sets TIF_SIGPENDING, but never clears it.
+	 */
+	recalc_sigpending_tsk(current);
+}
+
+static void ptrace_do_notify(int signr, int exit_code, int why)
+{
+	siginfo_t info;
+
+	memset(&info, 0, sizeof info);
+	info.si_signo = signr;
+	info.si_code = exit_code;
+	info.si_pid = task_pid_vnr(current);
+	info.si_uid = current_uid();
+
+	/* Let the debugger run.  */
+	ptrace_stop(exit_code, why, 1, &info);
+}
+
+void ptrace_notify(int exit_code)
+{
+	BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
+
+	spin_lock_irq(&current->sighand->siglock);
+	ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
+	spin_unlock_irq(&current->sighand->siglock);
+}
+
+/**
+ * do_signal_stop - handle group stop for SIGSTOP and other stop signals
+ * @signr: signr causing group stop if initiating
+ *
+ * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
+ * and participate in it.  If already set, participate in the existing
+ * group stop.  If participated in a group stop (and thus slept), %true is
+ * returned with siglock released.
+ *
+ * If ptraced, this function doesn't handle stop itself.  Instead,
+ * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
+ * untouched.  The caller must ensure that INTERRUPT trap handling takes
+ * places afterwards.
+ *
+ * CONTEXT:
+ * Must be called with @current->sighand->siglock held, which is released
+ * on %true return.
+ *
+ * RETURNS:
+ * %false if group stop is already cancelled or ptrace trap is scheduled.
+ * %true if participated in group stop.
+ */
+static bool do_signal_stop(int signr)
+	__releases(&current->sighand->siglock)
+{
+	struct signal_struct *sig = current->signal;
+
+	if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
+		unsigned int gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
+		struct task_struct *t;
+
+		/* signr will be recorded in task->jobctl for retries */
+		WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
+
+		if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
+		    unlikely(signal_group_exit(sig)))
+			return false;
+		/*
+		 * There is no group stop already in progress.  We must
+		 * initiate one now.
+		 *
+		 * While ptraced, a task may be resumed while group stop is
+		 * still in effect and then receive a stop signal and
+		 * initiate another group stop.  This deviates from the
+		 * usual behavior as two consecutive stop signals can't
+		 * cause two group stops when !ptraced.  That is why we
+		 * also check !task_is_stopped(t) below.
+		 *
+		 * The condition can be distinguished by testing whether
+		 * SIGNAL_STOP_STOPPED is already set.  Don't generate
+		 * group_exit_code in such case.
+		 *
+		 * This is not necessary for SIGNAL_STOP_CONTINUED because
+		 * an intervening stop signal is required to cause two
+		 * continued events regardless of ptrace.
+		 */
+		if (!(sig->flags & SIGNAL_STOP_STOPPED))
+			sig->group_exit_code = signr;
+
+		sig->group_stop_count = 0;
+
+		if (task_set_jobctl_pending(current, signr | gstop))
+			sig->group_stop_count++;
+
+		for (t = next_thread(current); t != current;
+		     t = next_thread(t)) {
+			/*
+			 * Setting state to TASK_STOPPED for a group
+			 * stop is always done with the siglock held,
+			 * so this check has no races.
+			 */
+			if (!task_is_stopped(t) &&
+			    task_set_jobctl_pending(t, signr | gstop)) {
+				sig->group_stop_count++;
+				if (likely(!(t->ptrace & PT_SEIZED)))
+					signal_wake_up(t, 0);
+				else
+					ptrace_trap_notify(t);
+			}
+		}
+	}
+
+	if (likely(!current->ptrace)) {
+		int notify = 0;
+
+		/*
+		 * If there are no other threads in the group, or if there
+		 * is a group stop in progress and we are the last to stop,
+		 * report to the parent.
+		 */
+		if (task_participate_group_stop(current))
+			notify = CLD_STOPPED;
+
+		__set_current_state(TASK_STOPPED);
+		spin_unlock_irq(&current->sighand->siglock);
+
+		/*
+		 * Notify the parent of the group stop completion.  Because
+		 * we're not holding either the siglock or tasklist_lock
+		 * here, ptracer may attach inbetween; however, this is for
+		 * group stop and should always be delivered to the real
+		 * parent of the group leader.  The new ptracer will get
+		 * its notification when this task transitions into
+		 * TASK_TRACED.
+		 */
+		if (notify) {
+			read_lock(&tasklist_lock);
+			do_notify_parent_cldstop(current, false, notify);
+			read_unlock(&tasklist_lock);
+		}
+
+		/* Now we don't run again until woken by SIGCONT or SIGKILL */
+		schedule();
+		return true;
+	} else {
+		/*
+		 * While ptraced, group stop is handled by STOP trap.
+		 * Schedule it and let the caller deal with it.
+		 */
+		task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
+		return false;
+	}
+}
+
+/**
+ * do_jobctl_trap - take care of ptrace jobctl traps
+ *
+ * When PT_SEIZED, it's used for both group stop and explicit
+ * SEIZE/INTERRUPT traps.  Both generate PTRACE_EVENT_STOP trap with
+ * accompanying siginfo.  If stopped, lower eight bits of exit_code contain
+ * the stop signal; otherwise, %SIGTRAP.
+ *
+ * When !PT_SEIZED, it's used only for group stop trap with stop signal
+ * number as exit_code and no siginfo.
+ *
+ * CONTEXT:
+ * Must be called with @current->sighand->siglock held, which may be
+ * released and re-acquired before returning with intervening sleep.
+ */
+static void do_jobctl_trap(void)
+{
+	struct signal_struct *signal = current->signal;
+	int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
+
+	if (current->ptrace & PT_SEIZED) {
+		if (!signal->group_stop_count &&
+		    !(signal->flags & SIGNAL_STOP_STOPPED))
+			signr = SIGTRAP;
+		WARN_ON_ONCE(!signr);
+		ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
+				 CLD_STOPPED);
+	} else {
+		WARN_ON_ONCE(!signr);
+		ptrace_stop(signr, CLD_STOPPED, 0, NULL);
+		current->exit_code = 0;
+	}
+}
+
+static int ptrace_signal(int signr, siginfo_t *info,
+			 struct pt_regs *regs, void *cookie)
+{
+	ptrace_signal_deliver(regs, cookie);
+	/*
+	 * We do not check sig_kernel_stop(signr) but set this marker
+	 * unconditionally because we do not know whether debugger will
+	 * change signr. This flag has no meaning unless we are going
+	 * to stop after return from ptrace_stop(). In this case it will
+	 * be checked in do_signal_stop(), we should only stop if it was
+	 * not cleared by SIGCONT while we were sleeping. See also the
+	 * comment in dequeue_signal().
+	 */
+	current->jobctl |= JOBCTL_STOP_DEQUEUED;
+	ptrace_stop(signr, CLD_TRAPPED, 0, info);
+
+	/* We're back.  Did the debugger cancel the sig?  */
+	signr = current->exit_code;
+	if (signr == 0)
+		return signr;
+
+	current->exit_code = 0;
+
+	/*
+	 * Update the siginfo structure if the signal has
+	 * changed.  If the debugger wanted something
+	 * specific in the siginfo structure then it should
+	 * have updated *info via PTRACE_SETSIGINFO.
+	 */
+	if (signr != info->si_signo) {
+		info->si_signo = signr;
+		info->si_errno = 0;
+		info->si_code = SI_USER;
+		rcu_read_lock();
+		info->si_pid = task_pid_vnr(current->parent);
+		info->si_uid = map_cred_ns(__task_cred(current->parent),
+				current_user_ns());
+		rcu_read_unlock();
+	}
+
+	/* If the (new) signal is now blocked, requeue it.  */
+	if (sigismember(&current->blocked, signr)) {
+		specific_send_sig_info(signr, info, current);
+		signr = 0;
+	}
+
+	return signr;
+}
+
+int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
+			  struct pt_regs *regs, void *cookie)
+{
+	struct sighand_struct *sighand = current->sighand;
+	struct signal_struct *signal = current->signal;
+	int signr;
+
+relock:
+	/*
+	 * We'll jump back here after any time we were stopped in TASK_STOPPED.
+	 * While in TASK_STOPPED, we were considered "frozen enough".
+	 * Now that we woke up, it's crucial if we're supposed to be
+	 * frozen that we freeze now before running anything substantial.
+	 */
+	try_to_freeze_nowarn();
+
+	spin_lock_irq(&sighand->siglock);
+	/*
+	 * Every stopped thread goes here after wakeup. Check to see if
+	 * we should notify the parent, prepare_signal(SIGCONT) encodes
+	 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
+	 */
+	if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
+		int why;
+
+		if (signal->flags & SIGNAL_CLD_CONTINUED)
+			why = CLD_CONTINUED;
+		else
+			why = CLD_STOPPED;
+
+		signal->flags &= ~SIGNAL_CLD_MASK;
+
+		spin_unlock_irq(&sighand->siglock);
+
+		/*
+		 * Notify the parent that we're continuing.  This event is
+		 * always per-process and doesn't make whole lot of sense
+		 * for ptracers, who shouldn't consume the state via
+		 * wait(2) either, but, for backward compatibility, notify
+		 * the ptracer of the group leader too unless it's gonna be
+		 * a duplicate.
+		 */
+		read_lock(&tasklist_lock);
+		do_notify_parent_cldstop(current, false, why);
+
+		if (ptrace_reparented(current->group_leader))
+			do_notify_parent_cldstop(current->group_leader,
+						true, why);
+		read_unlock(&tasklist_lock);
+
+		goto relock;
+	}
+
+	for (;;) {
+		struct k_sigaction *ka;
+
+		if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
+		    do_signal_stop(0))
+			goto relock;
+
+		if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
+			do_jobctl_trap();
+			spin_unlock_irq(&sighand->siglock);
+			goto relock;
+		}
+
+		signr = dequeue_signal(current, &current->blocked, info);
+
+		if (!signr)
+			break; /* will return 0 */
+
+		if (unlikely(current->ptrace) && signr != SIGKILL) {
+			signr = ptrace_signal(signr, info,
+					      regs, cookie);
+			if (!signr)
+				continue;
+		}
+
+		ka = &sighand->action[signr-1];
+
+		/* Trace actually delivered signals. */
+		trace_signal_deliver(signr, info, ka);
+
+		if (ka->sa.sa_handler == SIG_IGN) /* Do nothing.  */
+			continue;
+		if (ka->sa.sa_handler != SIG_DFL) {
+			/* Run the handler.  */
+			*return_ka = *ka;
+
+			if (ka->sa.sa_flags & SA_ONESHOT)
+				ka->sa.sa_handler = SIG_DFL;
+
+			break; /* will return non-zero "signr" value */
+		}
+
+		/*
+		 * Now we are doing the default action for this signal.
+		 */
+		if (sig_kernel_ignore(signr)) /* Default is nothing. */
+			continue;
+
+		/*
+		 * Global init gets no signals it doesn't want.
+		 * Container-init gets no signals it doesn't want from same
+		 * container.
+		 *
+		 * Note that if global/container-init sees a sig_kernel_only()
+		 * signal here, the signal must have been generated internally
+		 * or must have come from an ancestor namespace. In either
+		 * case, the signal cannot be dropped.
+		 */
+		if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
+				!sig_kernel_only(signr))
+			continue;
+
+		if (sig_kernel_stop(signr)) {
+			/*
+			 * The default action is to stop all threads in
+			 * the thread group.  The job control signals
+			 * do nothing in an orphaned pgrp, but SIGSTOP
+			 * always works.  Note that siglock needs to be
+			 * dropped during the call to is_orphaned_pgrp()
+			 * because of lock ordering with tasklist_lock.
+			 * This allows an intervening SIGCONT to be posted.
+			 * We need to check for that and bail out if necessary.
+			 */
+			if (signr != SIGSTOP) {
+				spin_unlock_irq(&sighand->siglock);
+
+				/* signals can be posted during this window */
+
+				if (is_current_pgrp_orphaned())
+					goto relock;
+
+				spin_lock_irq(&sighand->siglock);
+			}
+
+			if (likely(do_signal_stop(info->si_signo))) {
+				/* It released the siglock.  */
+				goto relock;
+			}
+
+			/*
+			 * We didn't actually stop, due to a race
+			 * with SIGCONT or something like that.
+			 */
+			continue;
+		}
+
+		spin_unlock_irq(&sighand->siglock);
+
+		/*
+		 * Anything else is fatal, maybe with a core dump.
+		 */
+		current->flags |= PF_SIGNALED;
+
+		if (sig_kernel_coredump(signr)) {
+			if (print_fatal_signals)
+				print_fatal_signal(regs, info->si_signo);
+			/*
+			 * If it was able to dump core, this kills all
+			 * other threads in the group and synchronizes with
+			 * their demise.  If we lost the race with another
+			 * thread getting here, it set group_exit_code
+			 * first and our do_group_exit call below will use
+			 * that value and ignore the one we pass it.
+			 */
+			do_coredump(info->si_signo, info->si_signo, regs);
+		}
+
+		/*
+		 * Death signals, no core dump.
+		 */
+		do_group_exit(info->si_signo);
+		/* NOTREACHED */
+	}
+	spin_unlock_irq(&sighand->siglock);
+	return signr;
+}
+
+/**
+ * block_sigmask - add @ka's signal mask to current->blocked
+ * @ka: action for @signr
+ * @signr: signal that has been successfully delivered
+ *
+ * This function should be called when a signal has succesfully been
+ * delivered. It adds the mask of signals for @ka to current->blocked
+ * so that they are blocked during the execution of the signal
+ * handler. In addition, @signr will be blocked unless %SA_NODEFER is
+ * set in @ka->sa.sa_flags.
+ */
+void block_sigmask(struct k_sigaction *ka, int signr)
+{
+	sigset_t blocked;
+
+	sigorsets(&blocked, &current->blocked, &ka->sa.sa_mask);
+	if (!(ka->sa.sa_flags & SA_NODEFER))
+		sigaddset(&blocked, signr);
+	set_current_blocked(&blocked);
+}
+
+/*
+ * It could be that complete_signal() picked us to notify about the
+ * group-wide signal. Other threads should be notified now to take
+ * the shared signals in @which since we will not.
+ */
+static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
+{
+	sigset_t retarget;
+	struct task_struct *t;
+
+	sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
+	if (sigisemptyset(&retarget))
+		return;
+
+	t = tsk;
+	while_each_thread(tsk, t) {
+		if (t->flags & PF_EXITING)
+			continue;
+
+		if (!has_pending_signals(&retarget, &t->blocked))
+			continue;
+		/* Remove the signals this thread can handle. */
+		sigandsets(&retarget, &retarget, &t->blocked);
+
+		if (!signal_pending(t))
+			signal_wake_up(t, 0);
+
+		if (sigisemptyset(&retarget))
+			break;
+	}
+}
+
+void exit_signals(struct task_struct *tsk)
+{
+	int group_stop = 0;
+	sigset_t unblocked;
+
+	/*
+	 * @tsk is about to have PF_EXITING set - lock out users which
+	 * expect stable threadgroup.
+	 */
+	threadgroup_change_begin(tsk);
+
+	if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
+		tsk->flags |= PF_EXITING;
+		threadgroup_change_end(tsk);
+		return;
+	}
+
+	spin_lock_irq(&tsk->sighand->siglock);
+	/*
+	 * From now this task is not visible for group-wide signals,
+	 * see wants_signal(), do_signal_stop().
+	 */
+	tsk->flags |= PF_EXITING;
+
+	threadgroup_change_end(tsk);
+
+	if (!signal_pending(tsk))
+		goto out;
+
+	unblocked = tsk->blocked;
+	signotset(&unblocked);
+	retarget_shared_pending(tsk, &unblocked);
+
+	if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
+	    task_participate_group_stop(tsk))
+		group_stop = CLD_STOPPED;
+out:
+	spin_unlock_irq(&tsk->sighand->siglock);
+
+	/*
+	 * If group stop has completed, deliver the notification.  This
+	 * should always go to the real parent of the group leader.
+	 */
+	if (unlikely(group_stop)) {
+		read_lock(&tasklist_lock);
+		do_notify_parent_cldstop(tsk, false, group_stop);
+		read_unlock(&tasklist_lock);
+	}
+}
+
+EXPORT_SYMBOL(recalc_sigpending);
+EXPORT_SYMBOL_GPL(dequeue_signal);
+EXPORT_SYMBOL(flush_signals);
+EXPORT_SYMBOL(force_sig);
+EXPORT_SYMBOL(send_sig);
+EXPORT_SYMBOL(send_sig_info);
+EXPORT_SYMBOL(sigprocmask);
+EXPORT_SYMBOL(block_all_signals);
+EXPORT_SYMBOL(unblock_all_signals);
+
+
+/*
+ * System call entry points.
+ */
+
+/**
+ *  sys_restart_syscall - restart a system call
+ */
+SYSCALL_DEFINE0(restart_syscall)
+{
+	struct restart_block *restart = &current_thread_info()->restart_block;
+	return restart->fn(restart);
+}
+
+long do_no_restart_syscall(struct restart_block *param)
+{
+	return -EINTR;
+}
+
+static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
+{
+	if (signal_pending(tsk) && !thread_group_empty(tsk)) {
+		sigset_t newblocked;
+		/* A set of now blocked but previously unblocked signals. */
+		sigandnsets(&newblocked, newset, &current->blocked);
+		retarget_shared_pending(tsk, &newblocked);
+	}
+	tsk->blocked = *newset;
+	recalc_sigpending();
+}
+
+/**
+ * set_current_blocked - change current->blocked mask
+ * @newset: new mask
+ *
+ * It is wrong to change ->blocked directly, this helper should be used
+ * to ensure the process can't miss a shared signal we are going to block.
+ */
+void set_current_blocked(const sigset_t *newset)
+{
+	struct task_struct *tsk = current;
+
+	spin_lock_irq(&tsk->sighand->siglock);
+	__set_task_blocked(tsk, newset);
+	spin_unlock_irq(&tsk->sighand->siglock);
+}
+
+/*
+ * This is also useful for kernel threads that want to temporarily
+ * (or permanently) block certain signals.
+ *
+ * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
+ * interface happily blocks "unblockable" signals like SIGKILL
+ * and friends.
+ */
+int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
+{
+	struct task_struct *tsk = current;
+	sigset_t newset;
+
+	/* Lockless, only current can change ->blocked, never from irq */
+	if (oldset)
+		*oldset = tsk->blocked;
+
+	switch (how) {
+	case SIG_BLOCK:
+		sigorsets(&newset, &tsk->blocked, set);
+		break;
+	case SIG_UNBLOCK:
+		sigandnsets(&newset, &tsk->blocked, set);
+		break;
+	case SIG_SETMASK:
+		newset = *set;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	set_current_blocked(&newset);
+	return 0;
+}
+
+/**
+ *  sys_rt_sigprocmask - change the list of currently blocked signals
+ *  @how: whether to add, remove, or set signals
+ *  @nset: stores pending signals
+ *  @oset: previous value of signal mask if non-null
+ *  @sigsetsize: size of sigset_t type
+ */
+SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
+		sigset_t __user *, oset, size_t, sigsetsize)
+{
+	sigset_t old_set, new_set;
+	int error;
+
+	/* XXX: Don't preclude handling different sized sigset_t's.  */
+	if (sigsetsize != sizeof(sigset_t))
+		return -EINVAL;
+
+	old_set = current->blocked;
+
+	if (nset) {
+		if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
+			return -EFAULT;
+		sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
+
+		error = sigprocmask(how, &new_set, NULL);
+		if (error)
+			return error;
+	}
+
+	if (oset) {
+		if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
+			return -EFAULT;
+	}
+
+	return 0;
+}
+
+long do_sigpending(void __user *set, unsigned long sigsetsize)
+{
+	long error = -EINVAL;
+	sigset_t pending;
+
+	if (sigsetsize > sizeof(sigset_t))
+		goto out;
+
+	spin_lock_irq(&current->sighand->siglock);
+	sigorsets(&pending, &current->pending.signal,
+		  &current->signal->shared_pending.signal);
+	spin_unlock_irq(&current->sighand->siglock);
+
+	/* Outside the lock because only this thread touches it.  */
+	sigandsets(&pending, &current->blocked, &pending);
+
+	error = -EFAULT;
+	if (!copy_to_user(set, &pending, sigsetsize))
+		error = 0;
+
+out:
+	return error;
+}
+
+/**
+ *  sys_rt_sigpending - examine a pending signal that has been raised
+ *			while blocked
+ *  @set: stores pending signals
+ *  @sigsetsize: size of sigset_t type or larger
+ */
+SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, set, size_t, sigsetsize)
+{
+	return do_sigpending(set, sigsetsize);
+}
+
+#ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
+
+int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
+{
+	int err;
+
+	if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
+		return -EFAULT;
+	if (from->si_code < 0)
+		return __copy_to_user(to, from, sizeof(siginfo_t))
+			? -EFAULT : 0;
+	/*
+	 * If you change siginfo_t structure, please be sure
+	 * this code is fixed accordingly.
+	 * Please remember to update the signalfd_copyinfo() function
+	 * inside fs/signalfd.c too, in case siginfo_t changes.
+	 * It should never copy any pad contained in the structure
+	 * to avoid security leaks, but must copy the generic
+	 * 3 ints plus the relevant union member.
+	 */
+	err = __put_user(from->si_signo, &to->si_signo);
+	err |= __put_user(from->si_errno, &to->si_errno);
+	err |= __put_user((short)from->si_code, &to->si_code);
+	switch (from->si_code & __SI_MASK) {
+	case __SI_KILL:
+		err |= __put_user(from->si_pid, &to->si_pid);
+		err |= __put_user(from->si_uid, &to->si_uid);
+		break;
+	case __SI_TIMER:
+		 err |= __put_user(from->si_tid, &to->si_tid);
+		 err |= __put_user(from->si_overrun, &to->si_overrun);
+		 err |= __put_user(from->si_ptr, &to->si_ptr);
+		break;
+	case __SI_POLL:
+		err |= __put_user(from->si_band, &to->si_band);
+		err |= __put_user(from->si_fd, &to->si_fd);
+		break;
+	case __SI_FAULT:
+		err |= __put_user(from->si_addr, &to->si_addr);
+#ifdef __ARCH_SI_TRAPNO
+		err |= __put_user(from->si_trapno, &to->si_trapno);
+#endif
+#ifdef BUS_MCEERR_AO
+		/*
+		 * Other callers might not initialize the si_lsb field,
+		 * so check explicitly for the right codes here.
+		 */
+		if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO)
+			err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
+#endif
+		break;
+	case __SI_CHLD:
+		err |= __put_user(from->si_pid, &to->si_pid);
+		err |= __put_user(from->si_uid, &to->si_uid);
+		err |= __put_user(from->si_status, &to->si_status);
+		err |= __put_user(from->si_utime, &to->si_utime);
+		err |= __put_user(from->si_stime, &to->si_stime);
+		break;
+	case __SI_RT: /* This is not generated by the kernel as of now. */
+	case __SI_MESGQ: /* But this is */
+		err |= __put_user(from->si_pid, &to->si_pid);
+		err |= __put_user(from->si_uid, &to->si_uid);
+		err |= __put_user(from->si_ptr, &to->si_ptr);
+		break;
+	default: /* this is just in case for now ... */
+		err |= __put_user(from->si_pid, &to->si_pid);
+		err |= __put_user(from->si_uid, &to->si_uid);
+		break;
+	}
+	return err;
+}
+
+#endif
+
+/**
+ *  do_sigtimedwait - wait for queued signals specified in @which
+ *  @which: queued signals to wait for
+ *  @info: if non-null, the signal's siginfo is returned here
+ *  @ts: upper bound on process time suspension
+ */
+int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
+			const struct timespec *ts)
+{
+	struct task_struct *tsk = current;
+	long timeout = MAX_SCHEDULE_TIMEOUT;
+	sigset_t mask = *which;
+	int sig;
+
+	if (ts) {
+		if (!timespec_valid(ts))
+			return -EINVAL;
+		timeout = timespec_to_jiffies(ts);
+		/*
+		 * We can be close to the next tick, add another one
+		 * to ensure we will wait at least the time asked for.
+		 */
+		if (ts->tv_sec || ts->tv_nsec)
+			timeout++;
+	}
+
+	/*
+	 * Invert the set of allowed signals to get those we want to block.
+	 */
+	sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
+	signotset(&mask);
+
+	spin_lock_irq(&tsk->sighand->siglock);
+	sig = dequeue_signal(tsk, &mask, info);
+	if (!sig && timeout) {
+		/*
+		 * None ready, temporarily unblock those we're interested
+		 * while we are sleeping in so that we'll be awakened when
+		 * they arrive. Unblocking is always fine, we can avoid
+		 * set_current_blocked().
+		 */
+		tsk->real_blocked = tsk->blocked;
+		sigandsets(&tsk->blocked, &tsk->blocked, &mask);
+		recalc_sigpending();
+		spin_unlock_irq(&tsk->sighand->siglock);
+
+		timeout = schedule_timeout_interruptible(timeout);
+
+		spin_lock_irq(&tsk->sighand->siglock);
+		__set_task_blocked(tsk, &tsk->real_blocked);
+		siginitset(&tsk->real_blocked, 0);
+		sig = dequeue_signal(tsk, &mask, info);
+	}
+	spin_unlock_irq(&tsk->sighand->siglock);
+
+	if (sig)
+		return sig;
+	return timeout ? -EINTR : -EAGAIN;
+}
+
+/**
+ *  sys_rt_sigtimedwait - synchronously wait for queued signals specified
+ *			in @uthese
+ *  @uthese: queued signals to wait for
+ *  @uinfo: if non-null, the signal's siginfo is returned here
+ *  @uts: upper bound on process time suspension
+ *  @sigsetsize: size of sigset_t type
+ */
+SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
+		siginfo_t __user *, uinfo, const struct timespec __user *, uts,
+		size_t, sigsetsize)
+{
+	sigset_t these;
+	struct timespec ts;
+	siginfo_t info;
+	int ret;
+
+	/* XXX: Don't preclude handling different sized sigset_t's.  */
+	if (sigsetsize != sizeof(sigset_t))
+		return -EINVAL;
+
+	if (copy_from_user(&these, uthese, sizeof(these)))
+		return -EFAULT;
+
+	if (uts) {
+		if (copy_from_user(&ts, uts, sizeof(ts)))
+			return -EFAULT;
+	}
+
+	ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
+
+	if (ret > 0 && uinfo) {
+		if (copy_siginfo_to_user(uinfo, &info))
+			ret = -EFAULT;
+	}
+
+	return ret;
+}
+
+/**
+ *  sys_kill - send a signal to a process
+ *  @pid: the PID of the process
+ *  @sig: signal to be sent
+ */
+SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
+{
+	struct siginfo info;
+
+	info.si_signo = sig;
+	info.si_errno = 0;
+	info.si_code = SI_USER;
+	info.si_pid = task_tgid_vnr(current);
+	info.si_uid = current_uid();
+
+	return kill_something_info(sig, &info, pid);
+}
+
+static int
+do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
+{
+	struct task_struct *p;
+	int error = -ESRCH;
+
+	rcu_read_lock();
+	p = find_task_by_vpid(pid);
+	if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
+		error = check_kill_permission(sig, info, p);
+		/*
+		 * The null signal is a permissions and process existence
+		 * probe.  No signal is actually delivered.
+		 */
+		if (!error && sig) {
+			error = do_send_sig_info(sig, info, p, false);
+			/*
+			 * If lock_task_sighand() failed we pretend the task
+			 * dies after receiving the signal. The window is tiny,
+			 * and the signal is private anyway.
+			 */
+			if (unlikely(error == -ESRCH))
+				error = 0;
+		}
+	}
+	rcu_read_unlock();
+
+	return error;
+}
+
+static int do_tkill(pid_t tgid, pid_t pid, int sig)
+{
+	struct siginfo info;
+
+	info.si_signo = sig;
+	info.si_errno = 0;
+	info.si_code = SI_TKILL;
+	info.si_pid = task_tgid_vnr(current);
+	info.si_uid = current_uid();
+
+	return do_send_specific(tgid, pid, sig, &info);
+}
+
+/**
+ *  sys_tgkill - send signal to one specific thread
+ *  @tgid: the thread group ID of the thread
+ *  @pid: the PID of the thread
+ *  @sig: signal to be sent
+ *
+ *  This syscall also checks the @tgid and returns -ESRCH even if the PID
+ *  exists but it's not belonging to the target process anymore. This
+ *  method solves the problem of threads exiting and PIDs getting reused.
+ */
+SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
+{
+	/* This is only valid for single tasks */
+	if (pid <= 0 || tgid <= 0)
+		return -EINVAL;
+
+	return do_tkill(tgid, pid, sig);
+}
+
+/**
+ *  sys_tkill - send signal to one specific task
+ *  @pid: the PID of the task
+ *  @sig: signal to be sent
+ *
+ *  Send a signal to only one task, even if it's a CLONE_THREAD task.
+ */
+SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
+{
+	/* This is only valid for single tasks */
+	if (pid <= 0)
+		return -EINVAL;
+
+	return do_tkill(0, pid, sig);
+}
+
+/**
+ *  sys_rt_sigqueueinfo - send signal information to a signal
+ *  @pid: the PID of the thread
+ *  @sig: signal to be sent
+ *  @uinfo: signal info to be sent
+ */
+SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
+		siginfo_t __user *, uinfo)
+{
+	siginfo_t info;
+
+	if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
+		return -EFAULT;
+
+	/* Not even root can pretend to send signals from the kernel.
+	 * Nor can they impersonate a kill()/tgkill(), which adds source info.
+	 */
+	if (info.si_code >= 0 || info.si_code == SI_TKILL) {
+		/* We used to allow any < 0 si_code */
+		WARN_ON_ONCE(info.si_code < 0);
+		return -EPERM;
+	}
+	info.si_signo = sig;
+
+	/* POSIX.1b doesn't mention process groups.  */
+	return kill_proc_info(sig, &info, pid);
+}
+
+long do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
+{
+	/* This is only valid for single tasks */
+	if (pid <= 0 || tgid <= 0)
+		return -EINVAL;
+
+	/* Not even root can pretend to send signals from the kernel.
+	 * Nor can they impersonate a kill()/tgkill(), which adds source info.
+	 */
+	if (info->si_code >= 0 || info->si_code == SI_TKILL) {
+		/* We used to allow any < 0 si_code */
+		WARN_ON_ONCE(info->si_code < 0);
+		return -EPERM;
+	}
+	info->si_signo = sig;
+
+	return do_send_specific(tgid, pid, sig, info);
+}
+
+SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
+		siginfo_t __user *, uinfo)
+{
+	siginfo_t info;
+
+	if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
+		return -EFAULT;
+
+	return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
+}
+
+int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
+{
+	struct task_struct *t = current;
+	struct k_sigaction *k;
+	sigset_t mask;
+
+	if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
+		return -EINVAL;
+
+	k = &t->sighand->action[sig-1];
+
+	spin_lock_irq(&current->sighand->siglock);
+	if (oact)
+		*oact = *k;
+
+	if (act) {
+		sigdelsetmask(&act->sa.sa_mask,
+			      sigmask(SIGKILL) | sigmask(SIGSTOP));
+		*k = *act;
+		/*
+		 * POSIX 3.3.1.3:
+		 *  "Setting a signal action to SIG_IGN for a signal that is
+		 *   pending shall cause the pending signal to be discarded,
+		 *   whether or not it is blocked."
+		 *
+		 *  "Setting a signal action to SIG_DFL for a signal that is
+		 *   pending and whose default action is to ignore the signal
+		 *   (for example, SIGCHLD), shall cause the pending signal to
+		 *   be discarded, whether or not it is blocked"
+		 */
+		if (sig_handler_ignored(sig_handler(t, sig), sig)) {
+			sigemptyset(&mask);
+			sigaddset(&mask, sig);
+			rm_from_queue_full(&mask, &t->signal->shared_pending);
+			do {
+				rm_from_queue_full(&mask, &t->pending);
+				t = next_thread(t);
+			} while (t != current);
+		}
+	}
+
+	spin_unlock_irq(&current->sighand->siglock);
+	return 0;
+}
+
+int 
+do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
+{
+	stack_t oss;
+	int error;
+
+	oss.ss_sp = (void __user *) current->sas_ss_sp;
+	oss.ss_size = current->sas_ss_size;
+	oss.ss_flags = sas_ss_flags(sp);
+
+	if (uss) {
+		void __user *ss_sp;
+		size_t ss_size;
+		int ss_flags;
+
+		error = -EFAULT;
+		if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
+			goto out;
+		error = __get_user(ss_sp, &uss->ss_sp) |
+			__get_user(ss_flags, &uss->ss_flags) |
+			__get_user(ss_size, &uss->ss_size);
+		if (error)
+			goto out;
+
+		error = -EPERM;
+		if (on_sig_stack(sp))
+			goto out;
+
+		error = -EINVAL;
+		/*
+		 * Note - this code used to test ss_flags incorrectly:
+		 *  	  old code may have been written using ss_flags==0
+		 *	  to mean ss_flags==SS_ONSTACK (as this was the only
+		 *	  way that worked) - this fix preserves that older
+		 *	  mechanism.
+		 */
+		if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
+			goto out;
+
+		if (ss_flags == SS_DISABLE) {
+			ss_size = 0;
+			ss_sp = NULL;
+		} else {
+			error = -ENOMEM;
+			if (ss_size < MINSIGSTKSZ)
+				goto out;
+		}
+
+		current->sas_ss_sp = (unsigned long) ss_sp;
+		current->sas_ss_size = ss_size;
+	}
+
+	error = 0;
+	if (uoss) {
+		error = -EFAULT;
+		if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
+			goto out;
+		error = __put_user(oss.ss_sp, &uoss->ss_sp) |
+			__put_user(oss.ss_size, &uoss->ss_size) |
+			__put_user(oss.ss_flags, &uoss->ss_flags);
+	}
+
+out:
+	return error;
+}
+
+#ifdef __ARCH_WANT_SYS_SIGPENDING
+
+/**
+ *  sys_sigpending - examine pending signals
+ *  @set: where mask of pending signal is returned
+ */
+SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
+{
+	return do_sigpending(set, sizeof(*set));
+}
+
+#endif
+
+#ifdef __ARCH_WANT_SYS_SIGPROCMASK
+/**
+ *  sys_sigprocmask - examine and change blocked signals
+ *  @how: whether to add, remove, or set signals
+ *  @nset: signals to add or remove (if non-null)
+ *  @oset: previous value of signal mask if non-null
+ *
+ * Some platforms have their own version with special arguments;
+ * others support only sys_rt_sigprocmask.
+ */
+
+SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
+		old_sigset_t __user *, oset)
+{
+	old_sigset_t old_set, new_set;
+	sigset_t new_blocked;
+
+	old_set = current->blocked.sig[0];
+
+	if (nset) {
+		if (copy_from_user(&new_set, nset, sizeof(*nset)))
+			return -EFAULT;
+		new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
+
+		new_blocked = current->blocked;
+
+		switch (how) {
+		case SIG_BLOCK:
+			sigaddsetmask(&new_blocked, new_set);
+			break;
+		case SIG_UNBLOCK:
+			sigdelsetmask(&new_blocked, new_set);
+			break;
+		case SIG_SETMASK:
+			new_blocked.sig[0] = new_set;
+			break;
+		default:
+			return -EINVAL;
+		}
+
+		set_current_blocked(&new_blocked);
+	}
+
+	if (oset) {
+		if (copy_to_user(oset, &old_set, sizeof(*oset)))
+			return -EFAULT;
+	}
+
+	return 0;
+}
+#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
+
+#ifdef __ARCH_WANT_SYS_RT_SIGACTION
+/**
+ *  sys_rt_sigaction - alter an action taken by a process
+ *  @sig: signal to be sent
+ *  @act: new sigaction
+ *  @oact: used to save the previous sigaction
+ *  @sigsetsize: size of sigset_t type
+ */
+SYSCALL_DEFINE4(rt_sigaction, int, sig,
+		const struct sigaction __user *, act,
+		struct sigaction __user *, oact,
+		size_t, sigsetsize)
+{
+	struct k_sigaction new_sa, old_sa;
+	int ret = -EINVAL;
+
+	/* XXX: Don't preclude handling different sized sigset_t's.  */
+	if (sigsetsize != sizeof(sigset_t))
+		goto out;
+
+	if (act) {
+		if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
+			return -EFAULT;
+	}
+
+	ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
+
+	if (!ret && oact) {
+		if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
+			return -EFAULT;
+	}
+out:
+	return ret;
+}
+#endif /* __ARCH_WANT_SYS_RT_SIGACTION */
+
+#ifdef __ARCH_WANT_SYS_SGETMASK
+
+/*
+ * For backwards compatibility.  Functionality superseded by sigprocmask.
+ */
+SYSCALL_DEFINE0(sgetmask)
+{
+	/* SMP safe */
+	return current->blocked.sig[0];
+}
+
+SYSCALL_DEFINE1(ssetmask, int, newmask)
+{
+	int old = current->blocked.sig[0];
+	sigset_t newset;
+
+	siginitset(&newset, newmask & ~(sigmask(SIGKILL) | sigmask(SIGSTOP)));
+	set_current_blocked(&newset);
+
+	return old;
+}
+#endif /* __ARCH_WANT_SGETMASK */
+
+#ifdef __ARCH_WANT_SYS_SIGNAL
+/*
+ * For backwards compatibility.  Functionality superseded by sigaction.
+ */
+SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
+{
+	struct k_sigaction new_sa, old_sa;
+	int ret;
+
+	new_sa.sa.sa_handler = handler;
+	new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
+	sigemptyset(&new_sa.sa.sa_mask);
+
+	ret = do_sigaction(sig, &new_sa, &old_sa);
+
+	return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
+}
+#endif /* __ARCH_WANT_SYS_SIGNAL */
+
+#ifdef __ARCH_WANT_SYS_PAUSE
+
+SYSCALL_DEFINE0(pause)
+{
+	while (!signal_pending(current)) {
+		current->state = TASK_INTERRUPTIBLE;
+		schedule();
+	}
+	return -ERESTARTNOHAND;
+}
+
+#endif
+
+#ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
+/**
+ *  sys_rt_sigsuspend - replace the signal mask for a value with the
+ *	@unewset value until a signal is received
+ *  @unewset: new signal mask value
+ *  @sigsetsize: size of sigset_t type
+ */
+SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
+{
+	sigset_t newset;
+
+	/* XXX: Don't preclude handling different sized sigset_t's.  */
+	if (sigsetsize != sizeof(sigset_t))
+		return -EINVAL;
+
+	if (copy_from_user(&newset, unewset, sizeof(newset)))
+		return -EFAULT;
+	sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
+
+	current->saved_sigmask = current->blocked;
+	set_current_blocked(&newset);
+
+	current->state = TASK_INTERRUPTIBLE;
+	schedule();
+	set_restore_sigmask();
+	return -ERESTARTNOHAND;
+}
+#endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
+
+__attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
+{
+	return NULL;
+}
+
+void __init signals_init(void)
+{
+	sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
+}
+
+#ifdef CONFIG_KGDB_KDB
+#include <linux/kdb.h>
+/*
+ * kdb_send_sig_info - Allows kdb to send signals without exposing
+ * signal internals.  This function checks if the required locks are
+ * available before calling the main signal code, to avoid kdb
+ * deadlocks.
+ */
+void
+kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
+{
+	static struct task_struct *kdb_prev_t;
+	int sig, new_t;
+	if (!spin_trylock(&t->sighand->siglock)) {
+		kdb_printf("Can't do kill command now.\n"
+			   "The sigmask lock is held somewhere else in "
+			   "kernel, try again later\n");
+		return;
+	}
+	spin_unlock(&t->sighand->siglock);
+	new_t = kdb_prev_t != t;
+	kdb_prev_t = t;
+	if (t->state != TASK_RUNNING && new_t) {
+		kdb_printf("Process is not RUNNING, sending a signal from "
+			   "kdb risks deadlock\n"
+			   "on the run queue locks. "
+			   "The signal has _not_ been sent.\n"
+			   "Reissue the kill command if you want to risk "
+			   "the deadlock.\n");
+		return;
+	}
+	sig = info->si_signo;
+	if (send_sig_info(sig, info, t))
+		kdb_printf("Fail to deliver Signal %d to process %d.\n",
+			   sig, t->pid);
+	else
+		kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
+}
+#endif	/* CONFIG_KGDB_KDB */