diff options
author | Srikant Patnaik | 2015-01-11 12:28:04 +0530 |
---|---|---|
committer | Srikant Patnaik | 2015-01-11 12:28:04 +0530 |
commit | 871480933a1c28f8a9fed4c4d34d06c439a7a422 (patch) | |
tree | 8718f573808810c2a1e8cb8fb6ac469093ca2784 /include/linux/srcu.h | |
parent | 9d40ac5867b9aefe0722bc1f110b965ff294d30d (diff) | |
download | FOSSEE-netbook-kernel-source-871480933a1c28f8a9fed4c4d34d06c439a7a422.tar.gz FOSSEE-netbook-kernel-source-871480933a1c28f8a9fed4c4d34d06c439a7a422.tar.bz2 FOSSEE-netbook-kernel-source-871480933a1c28f8a9fed4c4d34d06c439a7a422.zip |
Moved, renamed, and deleted files
The original directory structure was scattered and unorganized.
Changes are basically to make it look like kernel structure.
Diffstat (limited to 'include/linux/srcu.h')
-rw-r--r-- | include/linux/srcu.h | 239 |
1 files changed, 239 insertions, 0 deletions
diff --git a/include/linux/srcu.h b/include/linux/srcu.h new file mode 100644 index 00000000..d3d5fa54 --- /dev/null +++ b/include/linux/srcu.h @@ -0,0 +1,239 @@ +/* + * Sleepable Read-Copy Update mechanism for mutual exclusion + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * + * Copyright (C) IBM Corporation, 2006 + * + * Author: Paul McKenney <paulmck@us.ibm.com> + * + * For detailed explanation of Read-Copy Update mechanism see - + * Documentation/RCU/ *.txt + * + */ + +#ifndef _LINUX_SRCU_H +#define _LINUX_SRCU_H + +#include <linux/mutex.h> +#include <linux/rcupdate.h> + +struct srcu_struct_array { + int c[2]; +}; + +struct srcu_struct { + int completed; + struct srcu_struct_array __percpu *per_cpu_ref; + struct mutex mutex; +#ifdef CONFIG_DEBUG_LOCK_ALLOC + struct lockdep_map dep_map; +#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ +}; + +#ifndef CONFIG_PREEMPT +#define srcu_barrier() barrier() +#else /* #ifndef CONFIG_PREEMPT */ +#define srcu_barrier() +#endif /* #else #ifndef CONFIG_PREEMPT */ + +#ifdef CONFIG_DEBUG_LOCK_ALLOC + +int __init_srcu_struct(struct srcu_struct *sp, const char *name, + struct lock_class_key *key); + +#define init_srcu_struct(sp) \ +({ \ + static struct lock_class_key __srcu_key; \ + \ + __init_srcu_struct((sp), #sp, &__srcu_key); \ +}) + +#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ + +int init_srcu_struct(struct srcu_struct *sp); + +#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */ + +void cleanup_srcu_struct(struct srcu_struct *sp); +int __srcu_read_lock(struct srcu_struct *sp) __acquires(sp); +void __srcu_read_unlock(struct srcu_struct *sp, int idx) __releases(sp); +void synchronize_srcu(struct srcu_struct *sp); +void synchronize_srcu_expedited(struct srcu_struct *sp); +long srcu_batches_completed(struct srcu_struct *sp); + +#ifdef CONFIG_DEBUG_LOCK_ALLOC + +/** + * srcu_read_lock_held - might we be in SRCU read-side critical section? + * + * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an SRCU + * read-side critical section. In absence of CONFIG_DEBUG_LOCK_ALLOC, + * this assumes we are in an SRCU read-side critical section unless it can + * prove otherwise. + * + * Checks debug_lockdep_rcu_enabled() to prevent false positives during boot + * and while lockdep is disabled. + * + * Note that if the CPU is in the idle loop from an RCU point of view + * (ie: that we are in the section between rcu_idle_enter() and + * rcu_idle_exit()) then srcu_read_lock_held() returns false even if + * the CPU did an srcu_read_lock(). The reason for this is that RCU + * ignores CPUs that are in such a section, considering these as in + * extended quiescent state, so such a CPU is effectively never in an + * RCU read-side critical section regardless of what RCU primitives it + * invokes. This state of affairs is required --- we need to keep an + * RCU-free window in idle where the CPU may possibly enter into low + * power mode. This way we can notice an extended quiescent state to + * other CPUs that started a grace period. Otherwise we would delay any + * grace period as long as we run in the idle task. + * + * Similarly, we avoid claiming an SRCU read lock held if the current + * CPU is offline. + */ +static inline int srcu_read_lock_held(struct srcu_struct *sp) +{ + if (!debug_lockdep_rcu_enabled()) + return 1; + if (rcu_is_cpu_idle()) + return 0; + if (!rcu_lockdep_current_cpu_online()) + return 0; + return lock_is_held(&sp->dep_map); +} + +#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ + +static inline int srcu_read_lock_held(struct srcu_struct *sp) +{ + return 1; +} + +#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */ + +/** + * srcu_dereference_check - fetch SRCU-protected pointer for later dereferencing + * @p: the pointer to fetch and protect for later dereferencing + * @sp: pointer to the srcu_struct, which is used to check that we + * really are in an SRCU read-side critical section. + * @c: condition to check for update-side use + * + * If PROVE_RCU is enabled, invoking this outside of an RCU read-side + * critical section will result in an RCU-lockdep splat, unless @c evaluates + * to 1. The @c argument will normally be a logical expression containing + * lockdep_is_held() calls. + */ +#define srcu_dereference_check(p, sp, c) \ + __rcu_dereference_check((p), srcu_read_lock_held(sp) || (c), __rcu) + +/** + * srcu_dereference - fetch SRCU-protected pointer for later dereferencing + * @p: the pointer to fetch and protect for later dereferencing + * @sp: pointer to the srcu_struct, which is used to check that we + * really are in an SRCU read-side critical section. + * + * Makes rcu_dereference_check() do the dirty work. If PROVE_RCU + * is enabled, invoking this outside of an RCU read-side critical + * section will result in an RCU-lockdep splat. + */ +#define srcu_dereference(p, sp) srcu_dereference_check((p), (sp), 0) + +/** + * srcu_read_lock - register a new reader for an SRCU-protected structure. + * @sp: srcu_struct in which to register the new reader. + * + * Enter an SRCU read-side critical section. Note that SRCU read-side + * critical sections may be nested. However, it is illegal to + * call anything that waits on an SRCU grace period for the same + * srcu_struct, whether directly or indirectly. Please note that + * one way to indirectly wait on an SRCU grace period is to acquire + * a mutex that is held elsewhere while calling synchronize_srcu() or + * synchronize_srcu_expedited(). + * + * Note that srcu_read_lock() and the matching srcu_read_unlock() must + * occur in the same context, for example, it is illegal to invoke + * srcu_read_unlock() in an irq handler if the matching srcu_read_lock() + * was invoked in process context. + */ +static inline int srcu_read_lock(struct srcu_struct *sp) __acquires(sp) +{ + int retval = __srcu_read_lock(sp); + + rcu_lock_acquire(&(sp)->dep_map); + rcu_lockdep_assert(!rcu_is_cpu_idle(), + "srcu_read_lock() used illegally while idle"); + return retval; +} + +/** + * srcu_read_unlock - unregister a old reader from an SRCU-protected structure. + * @sp: srcu_struct in which to unregister the old reader. + * @idx: return value from corresponding srcu_read_lock(). + * + * Exit an SRCU read-side critical section. + */ +static inline void srcu_read_unlock(struct srcu_struct *sp, int idx) + __releases(sp) +{ + rcu_lockdep_assert(!rcu_is_cpu_idle(), + "srcu_read_unlock() used illegally while idle"); + rcu_lock_release(&(sp)->dep_map); + __srcu_read_unlock(sp, idx); +} + +/** + * srcu_read_lock_raw - register a new reader for an SRCU-protected structure. + * @sp: srcu_struct in which to register the new reader. + * + * Enter an SRCU read-side critical section. Similar to srcu_read_lock(), + * but avoids the RCU-lockdep checking. This means that it is legal to + * use srcu_read_lock_raw() in one context, for example, in an exception + * handler, and then have the matching srcu_read_unlock_raw() in another + * context, for example in the task that took the exception. + * + * However, the entire SRCU read-side critical section must reside within a + * single task. For example, beware of using srcu_read_lock_raw() in + * a device interrupt handler and srcu_read_unlock() in the interrupted + * task: This will not work if interrupts are threaded. + */ +static inline int srcu_read_lock_raw(struct srcu_struct *sp) +{ + unsigned long flags; + int ret; + + local_irq_save(flags); + ret = __srcu_read_lock(sp); + local_irq_restore(flags); + return ret; +} + +/** + * srcu_read_unlock_raw - unregister reader from an SRCU-protected structure. + * @sp: srcu_struct in which to unregister the old reader. + * @idx: return value from corresponding srcu_read_lock_raw(). + * + * Exit an SRCU read-side critical section without lockdep-RCU checking. + * See srcu_read_lock_raw() for more details. + */ +static inline void srcu_read_unlock_raw(struct srcu_struct *sp, int idx) +{ + unsigned long flags; + + local_irq_save(flags); + __srcu_read_unlock(sp, idx); + local_irq_restore(flags); +} + +#endif |