+++ /dev/null
-#ifndef __BACKPORT_LINUX_WW_MUTEX_H
-#define __BACKPORT_LINUX_WW_MUTEX_H
-
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,11,0)
-#include_next <linux/ww_mutex.h>
-#else
-#ifdef CPTCFG_BACKPORT_BUILD_WW_MUTEX
-/*
- * Wound/Wait Mutexes: blocking mutual exclusion locks with deadlock avoidance
- *
- * Original mutex implementation started by Ingo Molnar:
- *
- * Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
- *
- * Wound/wait implementation:
- * Copyright (C) 2013 Canonical Ltd.
- *
- * This file contains the main data structure and API definitions.
- */
-
-#include <linux/mutex.h>
-
-struct ww_class {
- atomic_long_t stamp;
- struct lock_class_key acquire_key;
- struct lock_class_key mutex_key;
- const char *acquire_name;
- const char *mutex_name;
-};
-
-struct ww_acquire_ctx {
- struct task_struct *task;
- unsigned long stamp;
- unsigned acquired;
-};
-
-struct ww_mutex {
- struct mutex base;
- struct ww_acquire_ctx *ctx;
-};
-
-# define __WW_CLASS_MUTEX_INITIALIZER(lockname, ww_class)
-
-#define __WW_CLASS_INITIALIZER(ww_class) \
- { .stamp = ATOMIC_LONG_INIT(0) \
- , .acquire_name = #ww_class "_acquire" \
- , .mutex_name = #ww_class "_mutex" }
-
-#define __WW_MUTEX_INITIALIZER(lockname, class) \
- { .base = { \__MUTEX_INITIALIZER(lockname) } \
- __WW_CLASS_MUTEX_INITIALIZER(lockname, class) }
-
-#define DEFINE_WW_CLASS(classname) \
- struct ww_class classname = __WW_CLASS_INITIALIZER(classname)
-
-#define DEFINE_WW_MUTEX(mutexname, ww_class) \
- struct ww_mutex mutexname = __WW_MUTEX_INITIALIZER(mutexname, ww_class)
-
-/**
- * ww_mutex_init - initialize the w/w mutex
- * @lock: the mutex to be initialized
- * @ww_class: the w/w class the mutex should belong to
- *
- * Initialize the w/w mutex to unlocked state and associate it with the given
- * class.
- *
- * It is not allowed to initialize an already locked mutex.
- */
-#define ww_mutex_init LINUX_BACKPORT(ww_mutex_init)
-static inline void ww_mutex_init(struct ww_mutex *lock,
- struct ww_class *ww_class)
-{
- __mutex_init(&lock->base, ww_class->mutex_name, &ww_class->mutex_key);
- lock->ctx = NULL;
-}
-
-/**
- * ww_acquire_init - initialize a w/w acquire context
- * @ctx: w/w acquire context to initialize
- * @ww_class: w/w class of the context
- *
- * Initializes an context to acquire multiple mutexes of the given w/w class.
- *
- * Context-based w/w mutex acquiring can be done in any order whatsoever within
- * a given lock class. Deadlocks will be detected and handled with the
- * wait/wound logic.
- *
- * Mixing of context-based w/w mutex acquiring and single w/w mutex locking can
- * result in undetected deadlocks and is so forbidden. Mixing different contexts
- * for the same w/w class when acquiring mutexes can also result in undetected
- * deadlocks, and is hence also forbidden. Both types of abuse will be caught by
- * enabling CONFIG_PROVE_LOCKING.
- *
- * Nesting of acquire contexts for _different_ w/w classes is possible, subject
- * to the usual locking rules between different lock classes.
- *
- * An acquire context must be released with ww_acquire_fini by the same task
- * before the memory is freed. It is recommended to allocate the context itself
- * on the stack.
- */
-#define ww_acquire_init LINUX_BACKPORT(ww_acquire_init)
-static inline void ww_acquire_init(struct ww_acquire_ctx *ctx,
- struct ww_class *ww_class)
-{
- ctx->task = current;
- ctx->stamp = atomic_long_inc_return(&ww_class->stamp);
- ctx->acquired = 0;
-}
-
-/**
- * ww_acquire_done - marks the end of the acquire phase
- * @ctx: the acquire context
- *
- * Marks the end of the acquire phase, any further w/w mutex lock calls using
- * this context are forbidden.
- *
- * Calling this function is optional, it is just useful to document w/w mutex
- * code and clearly designated the acquire phase from actually using the locked
- * data structures.
- */
-#define ww_acquire_done LINUX_BACKPORT(ww_acquire_done)
-static inline void ww_acquire_done(struct ww_acquire_ctx *ctx)
-{
-}
-
-/**
- * ww_acquire_fini - releases a w/w acquire context
- * @ctx: the acquire context to free
- *
- * Releases a w/w acquire context. This must be called _after_ all acquired w/w
- * mutexes have been released with ww_mutex_unlock.
- */
-#define ww_acquire_fini LINUX_BACKPORT(ww_acquire_fini)
-static inline void ww_acquire_fini(struct ww_acquire_ctx *ctx)
-{
-}
-
-#define __ww_mutex_lock LINUX_BACKPORT(__ww_mutex_lock)
-extern int __must_check __ww_mutex_lock(struct ww_mutex *lock,
- struct ww_acquire_ctx *ctx);
-#define __ww_mutex_lock_interruptible LINUX_BACKPORT(__ww_mutex_lock_interruptible)
-extern int __must_check __ww_mutex_lock_interruptible(struct ww_mutex *lock,
- struct ww_acquire_ctx *ctx);
-
-/**
- * ww_mutex_lock - acquire the w/w mutex
- * @lock: the mutex to be acquired
- * @ctx: w/w acquire context, or NULL to acquire only a single lock.
- *
- * Lock the w/w mutex exclusively for this task.
- *
- * Deadlocks within a given w/w class of locks are detected and handled with the
- * wait/wound algorithm. If the lock isn't immediately avaiable this function
- * will either sleep until it is (wait case). Or it selects the current context
- * for backing off by returning -EDEADLK (wound case). Trying to acquire the
- * same lock with the same context twice is also detected and signalled by
- * returning -EALREADY. Returns 0 if the mutex was successfully acquired.
- *
- * In the wound case the caller must release all currently held w/w mutexes for
- * the given context and then wait for this contending lock to be available by
- * calling ww_mutex_lock_slow. Alternatively callers can opt to not acquire this
- * lock and proceed with trying to acquire further w/w mutexes (e.g. when
- * scanning through lru lists trying to free resources).
- *
- * The mutex must later on be released by the same task that
- * acquired it. The task may not exit without first unlocking the mutex. Also,
- * kernel memory where the mutex resides must not be freed with the mutex still
- * locked. The mutex must first be initialized (or statically defined) before it
- * can be locked. memset()-ing the mutex to 0 is not allowed. The mutex must be
- * of the same w/w lock class as was used to initialize the acquire context.
- *
- * A mutex acquired with this function must be released with ww_mutex_unlock.
- */
-#define ww_mutex_lock LINUX_BACKPORT(ww_mutex_lock)
-static inline int ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
-{
- if (ctx)
- return __ww_mutex_lock(lock, ctx);
-
- mutex_lock(&lock->base);
- return 0;
-}
-
-/**
- * ww_mutex_lock_interruptible - acquire the w/w mutex, interruptible
- * @lock: the mutex to be acquired
- * @ctx: w/w acquire context
- *
- * Lock the w/w mutex exclusively for this task.
- *
- * Deadlocks within a given w/w class of locks are detected and handled with the
- * wait/wound algorithm. If the lock isn't immediately avaiable this function
- * will either sleep until it is (wait case). Or it selects the current context
- * for backing off by returning -EDEADLK (wound case). Trying to acquire the
- * same lock with the same context twice is also detected and signalled by
- * returning -EALREADY. Returns 0 if the mutex was successfully acquired. If a
- * signal arrives while waiting for the lock then this function returns -EINTR.
- *
- * In the wound case the caller must release all currently held w/w mutexes for
- * the given context and then wait for this contending lock to be available by
- * calling ww_mutex_lock_slow_interruptible. Alternatively callers can opt to
- * not acquire this lock and proceed with trying to acquire further w/w mutexes
- * (e.g. when scanning through lru lists trying to free resources).
- *
- * The mutex must later on be released by the same task that
- * acquired it. The task may not exit without first unlocking the mutex. Also,
- * kernel memory where the mutex resides must not be freed with the mutex still
- * locked. The mutex must first be initialized (or statically defined) before it
- * can be locked. memset()-ing the mutex to 0 is not allowed. The mutex must be
- * of the same w/w lock class as was used to initialize the acquire context.
- *
- * A mutex acquired with this function must be released with ww_mutex_unlock.
- */
-#define ww_mutex_lock_interruptible LINUX_BACKPORT(ww_mutex_lock_interruptible)
-static inline int __must_check ww_mutex_lock_interruptible(struct ww_mutex *lock,
- struct ww_acquire_ctx *ctx)
-{
- if (ctx)
- return __ww_mutex_lock_interruptible(lock, ctx);
- else
- return mutex_lock_interruptible(&lock->base);
-}
-
-/**
- * ww_mutex_lock_slow - slowpath acquiring of the w/w mutex
- * @lock: the mutex to be acquired
- * @ctx: w/w acquire context
- *
- * Acquires a w/w mutex with the given context after a wound case. This function
- * will sleep until the lock becomes available.
- *
- * The caller must have released all w/w mutexes already acquired with the
- * context and then call this function on the contended lock.
- *
- * Afterwards the caller may continue to (re)acquire the other w/w mutexes it
- * needs with ww_mutex_lock. Note that the -EALREADY return code from
- * ww_mutex_lock can be used to avoid locking this contended mutex twice.
- *
- * It is forbidden to call this function with any other w/w mutexes associated
- * with the context held. It is forbidden to call this on anything else than the
- * contending mutex.
- *
- * Note that the slowpath lock acquiring can also be done by calling
- * ww_mutex_lock directly. This function here is simply to help w/w mutex
- * locking code readability by clearly denoting the slowpath.
- */
-#define ww_mutex_lock_slow LINUX_BACKPORT(ww_mutex_lock_slow)
-static inline void
-ww_mutex_lock_slow(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
-{
- int ret;
- ret = ww_mutex_lock(lock, ctx);
- (void)ret;
-}
-
-/**
- * ww_mutex_lock_slow_interruptible - slowpath acquiring of the w/w mutex, interruptible
- * @lock: the mutex to be acquired
- * @ctx: w/w acquire context
- *
- * Acquires a w/w mutex with the given context after a wound case. This function
- * will sleep until the lock becomes available and returns 0 when the lock has
- * been acquired. If a signal arrives while waiting for the lock then this
- * function returns -EINTR.
- *
- * The caller must have released all w/w mutexes already acquired with the
- * context and then call this function on the contended lock.
- *
- * Afterwards the caller may continue to (re)acquire the other w/w mutexes it
- * needs with ww_mutex_lock. Note that the -EALREADY return code from
- * ww_mutex_lock can be used to avoid locking this contended mutex twice.
- *
- * It is forbidden to call this function with any other w/w mutexes associated
- * with the given context held. It is forbidden to call this on anything else
- * than the contending mutex.
- *
- * Note that the slowpath lock acquiring can also be done by calling
- * ww_mutex_lock_interruptible directly. This function here is simply to help
- * w/w mutex locking code readability by clearly denoting the slowpath.
- */
-#define ww_mutex_lock_slow_interruptible LINUX_BACKPORT(ww_mutex_lock_slow_interruptible)
-static inline int __must_check
-ww_mutex_lock_slow_interruptible(struct ww_mutex *lock,
- struct ww_acquire_ctx *ctx)
-{
- return ww_mutex_lock_interruptible(lock, ctx);
-}
-
-#define ww_mutex_unlock LINUX_BACKPORT(ww_mutex_unlock)
-extern void ww_mutex_unlock(struct ww_mutex *lock);
-
-/**
- * ww_mutex_trylock - tries to acquire the w/w mutex without acquire context
- * @lock: mutex to lock
- *
- * Trylocks a mutex without acquire context, so no deadlock detection is
- * possible. Returns 1 if the mutex has been acquired successfully, 0 otherwise.
- */
-#define ww_mutex_trylock LINUX_BACKPORT(ww_mutex_trylock)
-static inline int __must_check ww_mutex_trylock(struct ww_mutex *lock)
-{
- return mutex_trylock(&lock->base);
-}
-
-/***
- * ww_mutex_destroy - mark a w/w mutex unusable
- * @lock: the mutex to be destroyed
- *
- * This function marks the mutex uninitialized, and any subsequent
- * use of the mutex is forbidden. The mutex must not be locked when
- * this function is called.
- */
-#define ww_mutex_destroy LINUX_BACKPORT(ww_mutex_destroy)
-static inline void ww_mutex_destroy(struct ww_mutex *lock)
-{
- mutex_destroy(&lock->base);
-}
-
-/**
- * ww_mutex_is_locked - is the w/w mutex locked
- * @lock: the mutex to be queried
- *
- * Returns 1 if the mutex is locked, 0 if unlocked.
- */
-#define ww_mutex_is_locked LINUX_BACKPORT(ww_mutex_is_locked)
-static inline bool ww_mutex_is_locked(struct ww_mutex *lock)
-{
- return mutex_is_locked(&lock->base);
-}
-
-#endif /* CPTCFG_BACKPORT_BUILD_WW_MUTEX */
-#endif /* LINUX_VERSION_CODE >= KERNEL_VERSION(3,11,0) */
-#endif /* __BACKPORT_LINUX_WW_MUTEX_H */
+++ /dev/null
-/*
- * Copyright (c) 2013 Luis R. Rodriguez <mcgrof@do-not-panic.com>
- *
- * Backport ww mutex for older kernels. This is not supported when
- * DEBUG_MUTEXES or DEBUG_LOCK_ALLOC is enabled.
- *
- * Taken from: kernel/mutex.c - via linux-stable v3.11-rc2
- *
- * Mutexes: blocking mutual exclusion locks
- *
- * Started by Ingo Molnar:
- *
- * Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
- *
- * Many thanks to Arjan van de Ven, Thomas Gleixner, Steven Rostedt and
- * David Howells for suggestions and improvements.
- *
- * - Adaptive spinning for mutexes by Peter Zijlstra. (Ported to mainline
- * from the -rt tree, where it was originally implemented for rtmutexes
- * by Steven Rostedt, based on work by Gregory Haskins, Peter Morreale
- * and Sven Dietrich.
- *
- * Also see Documentation/mutex-design.txt.
- */
-
-#include <linux/mutex.h>
-#include <linux/ww_mutex.h>
-#include <asm/mutex.h>
-#include <linux/sched.h>
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,9,0)
-#include <linux/sched/rt.h>
-#endif
-#include <linux/export.h>
-#include <linux/spinlock.h>
-#include <linux/interrupt.h>
-#include <linux/debug_locks.h>
-#include <linux/version.h>
-
-/*
- * A negative mutex count indicates that waiters are sleeping waiting for the
- * mutex.
- */
-#define MUTEX_SHOW_NO_WAITER(mutex) (atomic_read(&(mutex)->count) >= 0)
-
-#define spin_lock_mutex(lock, flags) \
- do { spin_lock(lock); (void)(flags); } while (0)
-#define spin_unlock_mutex(lock, flags) \
- do { spin_unlock(lock); (void)(flags); } while (0)
-#define mutex_remove_waiter(lock, waiter, ti) \
- __list_del((waiter)->list.prev, (waiter)->list.next)
-
-#ifdef CONFIG_SMP
-static inline void mutex_set_owner(struct mutex *lock)
-{
- lock->owner = current;
-}
-
-static inline void mutex_clear_owner(struct mutex *lock)
-{
- lock->owner = NULL;
-}
-#else
-static inline void mutex_set_owner(struct mutex *lock)
-{
-}
-
-static inline void mutex_clear_owner(struct mutex *lock)
-{
-}
-#endif
-
-
-#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,10,0) /* 2bd2c92c and 41fcb9f2 */
-/*
- * In order to avoid a stampede of mutex spinners from acquiring the mutex
- * more or less simultaneously, the spinners need to acquire a MCS lock
- * first before spinning on the owner field.
- *
- * We don't inline mspin_lock() so that perf can correctly account for the
- * time spent in this lock function.
- */
-struct mspin_node {
- struct mspin_node *next ;
- int locked; /* 1 if lock acquired */
-};
-#define MLOCK(mutex) ((struct mspin_node **)&((mutex)->spin_mlock))
-
-static noinline
-void mspin_lock(struct mspin_node **lock, struct mspin_node *node)
-{
- struct mspin_node *prev;
-
- /* Init node */
- node->locked = 0;
- node->next = NULL;
-
- prev = xchg(lock, node);
- if (likely(prev == NULL)) {
- /* Lock acquired */
- node->locked = 1;
- return;
- }
- ACCESS_ONCE(prev->next) = node;
- smp_wmb();
- /* Wait until the lock holder passes the lock down */
- while (!ACCESS_ONCE(node->locked))
- arch_mutex_cpu_relax();
-}
-
-static void mspin_unlock(struct mspin_node **lock, struct mspin_node *node)
-{
- struct mspin_node *next = ACCESS_ONCE(node->next);
-
- if (likely(!next)) {
- /*
- * Release the lock by setting it to NULL
- */
- if (cmpxchg(lock, node, NULL) == node)
- return;
- /* Wait until the next pointer is set */
- while (!(next = ACCESS_ONCE(node->next)))
- arch_mutex_cpu_relax();
- }
- ACCESS_ONCE(next->locked) = 1;
- smp_wmb();
-}
-
-/*
- * Mutex spinning code migrated from kernel/sched/core.c
- */
-
-static inline bool owner_running(struct mutex *lock, struct task_struct *owner)
-{
- if (lock->owner != owner)
- return false;
-
- /*
- * Ensure we emit the owner->on_cpu, dereference _after_ checking
- * lock->owner still matches owner, if that fails, owner might
- * point to free()d memory, if it still matches, the rcu_read_lock()
- * ensures the memory stays valid.
- */
- barrier();
-
- return owner->on_cpu;
-}
-
-/*
- * Look out! "owner" is an entirely speculative pointer
- * access and not reliable.
- */
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,10,0)
-static noinline
-#endif
-int mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner)
-{
- rcu_read_lock();
- while (owner_running(lock, owner)) {
- if (need_resched())
- break;
-
- arch_mutex_cpu_relax();
- }
- rcu_read_unlock();
-
- /*
- * We break out the loop above on need_resched() and when the
- * owner changed, which is a sign for heavy contention. Return
- * success only when lock->owner is NULL.
- */
- return lock->owner == NULL;
-}
-
-/*
- * Initial check for entering the mutex spinning loop
- */
-static inline int mutex_can_spin_on_owner(struct mutex *lock)
-{
- int retval = 1;
-
- rcu_read_lock();
- if (lock->owner)
- retval = lock->owner->on_cpu;
- rcu_read_unlock();
- /*
- * if lock->owner is not set, the mutex owner may have just acquired
- * it and not set the owner yet or the mutex has been released.
- */
- return retval;
-}
-#else /* Backport 2bd2c92c: help keep backport_mutex_lock_common() clean */
-
-struct mspin_node {
-};
-#define MLOCK(mutex) NULL
-
-static noinline
-void mspin_lock(struct mspin_node **lock, struct mspin_node *node)
-{
-}
-
-static void mspin_unlock(struct mspin_node **lock, struct mspin_node *node)
-{
-}
-
-static inline bool owner_running(struct mutex *lock, struct task_struct *owner)
-{
- return false;
-}
-
-int mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner)
-{
- return 1;
-}
-
-static inline int mutex_can_spin_on_owner(struct mutex *lock)
-{
- return 1;
-}
-#endif /* LINUX_VERSION_CODE >= KERNEL_VERSION(3,10,0) */
-#endif /* CONFIG_MUTEX_SPIN_ON_OWNER */
-
-/*
- * Release the lock, slowpath:
- */
-static inline void
-__mutex_unlock_common_slowpath(atomic_t *lock_count, int nested)
-{
- struct mutex *lock = container_of(lock_count, struct mutex, count);
- unsigned long flags;
-
- spin_lock_mutex(&lock->wait_lock, flags);
- mutex_release(&lock->dep_map, nested, _RET_IP_);
- /* debug_mutex_unlock(lock); */
-
- /*
- * some architectures leave the lock unlocked in the fastpath failure
- * case, others need to leave it locked. In the later case we have to
- * unlock it here
- */
- if (__mutex_slowpath_needs_to_unlock())
- atomic_set(&lock->count, 1);
-
- if (!list_empty(&lock->wait_list)) {
- /* get the first entry from the wait-list: */
- struct mutex_waiter *waiter =
- list_entry(lock->wait_list.next,
- struct mutex_waiter, list);
-
- /* debug_mutex_wake_waiter(lock, waiter); */
-
- wake_up_process(waiter->task);
- }
-
- spin_unlock_mutex(&lock->wait_lock, flags);
-}
-
-/*
- * Release the lock, slowpath:
- */
-static __used noinline void
-__mutex_unlock_slowpath(atomic_t *lock_count)
-{
- __mutex_unlock_common_slowpath(lock_count, 1);
-}
-
-/**
- * ww_mutex_unlock - release the w/w mutex
- * @lock: the mutex to be released
- *
- * Unlock a mutex that has been locked by this task previously with any of the
- * ww_mutex_lock* functions (with or without an acquire context). It is
- * forbidden to release the locks after releasing the acquire context.
- *
- * This function must not be used in interrupt context. Unlocking
- * of a unlocked mutex is not allowed.
- */
-void __sched ww_mutex_unlock(struct ww_mutex *lock)
-{
- /*
- * The unlocking fastpath is the 0->1 transition from 'locked'
- * into 'unlocked' state:
- */
- if (lock->ctx) {
- if (lock->ctx->acquired > 0)
- lock->ctx->acquired--;
- lock->ctx = NULL;
- }
-
- __mutex_fastpath_unlock(&lock->base.count, __mutex_unlock_slowpath);
-}
-EXPORT_SYMBOL_GPL(ww_mutex_unlock);
-
-static inline int __sched
-__mutex_lock_check_stamp(struct mutex *lock, struct ww_acquire_ctx *ctx)
-{
- struct ww_mutex *ww = container_of(lock, struct ww_mutex, base);
- struct ww_acquire_ctx *hold_ctx = ACCESS_ONCE(ww->ctx);
-
- if (!hold_ctx)
- return 0;
-
- if (unlikely(ctx == hold_ctx))
- return -EALREADY;
-
- if (ctx->stamp - hold_ctx->stamp <= LONG_MAX &&
- (ctx->stamp != hold_ctx->stamp || ctx > hold_ctx)) {
- return -EDEADLK;
- }
-
- return 0;
-}
-
-static __always_inline void ww_mutex_lock_acquired(struct ww_mutex *ww,
- struct ww_acquire_ctx *ww_ctx)
-{
- ww_ctx->acquired++;
-}
-
-/*
- * after acquiring lock with fastpath or when we lost out in contested
- * slowpath, set ctx and wake up any waiters so they can recheck.
- *
- * This function is never called when CONFIG_DEBUG_LOCK_ALLOC is set,
- * as the fastpath and opportunistic spinning are disabled in that case.
- */
-static __always_inline void
-ww_mutex_set_context_fastpath(struct ww_mutex *lock,
- struct ww_acquire_ctx *ctx)
-{
- unsigned long flags;
- struct mutex_waiter *cur;
-
- ww_mutex_lock_acquired(lock, ctx);
-
- lock->ctx = ctx;
-
- /*
- * The lock->ctx update should be visible on all cores before
- * the atomic read is done, otherwise contended waiters might be
- * missed. The contended waiters will either see ww_ctx == NULL
- * and keep spinning, or it will acquire wait_lock, add itself
- * to waiter list and sleep.
- */
- smp_mb(); /* ^^^ */
-
- /*
- * Check if lock is contended, if not there is nobody to wake up
- */
- if (likely(atomic_read(&lock->base.count) == 0))
- return;
-
- /*
- * Uh oh, we raced in fastpath, wake up everyone in this case,
- * so they can see the new lock->ctx.
- */
- spin_lock_mutex(&lock->base.wait_lock, flags);
- list_for_each_entry(cur, &lock->base.wait_list, list) {
- /* debug_mutex_wake_waiter(&lock->base, cur); */
- wake_up_process(cur->task);
- }
- spin_unlock_mutex(&lock->base.wait_lock, flags);
-}
-
-/**
- * backport_schedule_preempt_disabled - called with preemption disabled
- *
- * Backports c5491ea7. This is not exported so we leave it
- * here as this is the only current core user on backports.
- * Although available on >= 3.4 its only for in-kernel code so
- * we provide our own.
- *
- * Returns with preemption disabled. Note: preempt_count must be 1
- */
-static void __sched backport_schedule_preempt_disabled(void)
-{
- preempt_enable_no_resched();
- schedule();
- preempt_disable();
-}
-
-/*
- * Lock a mutex (possibly interruptible), slowpath:
- */
-static __always_inline int __sched
-__backport_mutex_lock_common(struct mutex *lock, long state,
- unsigned int subclass,
- struct lockdep_map *nest_lock, unsigned long ip,
- struct ww_acquire_ctx *ww_ctx)
-{
- struct task_struct *task = current;
- struct mutex_waiter waiter;
- unsigned long flags;
- int ret;
-
- preempt_disable();
- mutex_acquire_nest(&lock->dep_map, subclass, 0, nest_lock, ip);
-
-#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
- /*
- * Optimistic spinning.
- *
- * We try to spin for acquisition when we find that there are no
- * pending waiters and the lock owner is currently running on a
- * (different) CPU.
- *
- * The rationale is that if the lock owner is running, it is likely to
- * release the lock soon.
- *
- * Since this needs the lock owner, and this mutex implementation
- * doesn't track the owner atomically in the lock field, we need to
- * track it non-atomically.
- *
- * We can't do this for DEBUG_MUTEXES because that relies on wait_lock
- * to serialize everything.
- *
- * The mutex spinners are queued up using MCS lock so that only one
- * spinner can compete for the mutex. However, if mutex spinning isn't
- * going to happen, there is no point in going through the lock/unlock
- * overhead.
- */
- if (!mutex_can_spin_on_owner(lock))
- goto slowpath;
-
- for (;;) {
- struct task_struct *owner;
- struct mspin_node node;
-
- if (!__builtin_constant_p(ww_ctx == NULL) && ww_ctx->acquired > 0) {
- struct ww_mutex *ww;
-
- ww = container_of(lock, struct ww_mutex, base);
- /*
- * If ww->ctx is set the contents are undefined, only
- * by acquiring wait_lock there is a guarantee that
- * they are not invalid when reading.
- *
- * As such, when deadlock detection needs to be
- * performed the optimistic spinning cannot be done.
- */
- if (ACCESS_ONCE(ww->ctx))
- break;
- }
-
- /*
- * If there's an owner, wait for it to either
- * release the lock or go to sleep.
- */
- mspin_lock(MLOCK(lock), &node);
- owner = ACCESS_ONCE(lock->owner);
- if (owner && !mutex_spin_on_owner(lock, owner)) {
- mspin_unlock(MLOCK(lock), &node);
- break;
- }
-
- if ((atomic_read(&lock->count) == 1) &&
- (atomic_cmpxchg(&lock->count, 1, 0) == 1)) {
- lock_acquired(&lock->dep_map, ip);
- if (!__builtin_constant_p(ww_ctx == NULL)) {
- struct ww_mutex *ww;
- ww = container_of(lock, struct ww_mutex, base);
-
- ww_mutex_set_context_fastpath(ww, ww_ctx);
- }
-
- mutex_set_owner(lock);
- mspin_unlock(MLOCK(lock), &node);
- preempt_enable();
- return 0;
- }
- mspin_unlock(MLOCK(lock), &node);
-
- /*
- * When there's no owner, we might have preempted between the
- * owner acquiring the lock and setting the owner field. If
- * we're an RT task that will live-lock because we won't let
- * the owner complete.
- */
- if (!owner && (need_resched() || rt_task(task)))
- break;
-
- /*
- * The cpu_relax() call is a compiler barrier which forces
- * everything in this loop to be re-loaded. We don't need
- * memory barriers as we'll eventually observe the right
- * values at the cost of a few extra spins.
- */
- arch_mutex_cpu_relax();
- }
-slowpath:
-#endif
- spin_lock_mutex(&lock->wait_lock, flags);
-
- /* We don't support DEBUG_MUTEXES on the backport */
- /* debug_mutex_lock_common(lock, &waiter); */
- /* debug_mutex_add_waiter(lock, &waiter, task_thread_info(task)); */
-
- /* add waiting tasks to the end of the waitqueue (FIFO): */
- list_add_tail(&waiter.list, &lock->wait_list);
- waiter.task = task;
-
- if (MUTEX_SHOW_NO_WAITER(lock) && (atomic_xchg(&lock->count, -1) == 1))
- goto done;
-
- lock_contended(&lock->dep_map, ip);
-
- for (;;) {
- /*
- * Lets try to take the lock again - this is needed even if
- * we get here for the first time (shortly after failing to
- * acquire the lock), to make sure that we get a wakeup once
- * it's unlocked. Later on, if we sleep, this is the
- * operation that gives us the lock. We xchg it to -1, so
- * that when we release the lock, we properly wake up the
- * other waiters:
- */
- if (MUTEX_SHOW_NO_WAITER(lock) &&
- (atomic_xchg(&lock->count, -1) == 1))
- break;
-
- /*
- * got a signal? (This code gets eliminated in the
- * TASK_UNINTERRUPTIBLE case.)
- */
- if (unlikely(signal_pending_state(state, task))) {
- ret = -EINTR;
- goto err;
- }
-
- if (!__builtin_constant_p(ww_ctx == NULL) && ww_ctx->acquired > 0) {
- ret = __mutex_lock_check_stamp(lock, ww_ctx);
- if (ret)
- goto err;
- }
-
- __set_task_state(task, state);
-
- /* didn't get the lock, go to sleep: */
- spin_unlock_mutex(&lock->wait_lock, flags);
- backport_schedule_preempt_disabled();
- spin_lock_mutex(&lock->wait_lock, flags);
- }
-
-done:
- lock_acquired(&lock->dep_map, ip);
- /* got the lock - rejoice! */
- mutex_remove_waiter(lock, &waiter, current_thread_info());
- mutex_set_owner(lock);
-
- if (!__builtin_constant_p(ww_ctx == NULL)) {
- struct ww_mutex *ww = container_of(lock,
- struct ww_mutex,
- base);
- struct mutex_waiter *cur;
-
- /*
- * This branch gets optimized out for the common case,
- * and is only important for ww_mutex_lock.
- */
-
- ww_mutex_lock_acquired(ww, ww_ctx);
- ww->ctx = ww_ctx;
-
- /*
- * Give any possible sleeping processes the chance to wake up,
- * so they can recheck if they have to back off.
- */
- list_for_each_entry(cur, &lock->wait_list, list) {
- /* debug_mutex_wake_waiter(lock, cur); */
- wake_up_process(cur->task);
- }
- }
-
- /* set it to 0 if there are no waiters left: */
- if (likely(list_empty(&lock->wait_list)))
- atomic_set(&lock->count, 0);
-
- spin_unlock_mutex(&lock->wait_lock, flags);
-
- /* debug_mutex_free_waiter(&waiter); */
- preempt_enable();
-
- return 0;
-
-err:
- mutex_remove_waiter(lock, &waiter, task_thread_info(task));
- spin_unlock_mutex(&lock->wait_lock, flags);
- /* debug_mutex_free_waiter(&waiter); */
- mutex_release(&lock->dep_map, 1, ip);
- preempt_enable();
- return ret;
-}
-
-static noinline int __sched
-__ww_mutex_lock_slowpath(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
-{
- return __backport_mutex_lock_common(&lock->base, TASK_UNINTERRUPTIBLE, 0,
- NULL, _RET_IP_, ctx);
-}
-
-static noinline int __sched
-__ww_mutex_lock_interruptible_slowpath(struct ww_mutex *lock,
- struct ww_acquire_ctx *ctx)
-{
- return __backport_mutex_lock_common(&lock->base, TASK_INTERRUPTIBLE, 0,
- NULL, _RET_IP_, ctx);
-}
-
-/**
- * __mutex_fastpath_lock_retval - try to take the lock by moving the count
- * from 1 to a 0 value
- * @count: pointer of type atomic_t
- *
- * For backporting purposes we can't use the older kernel's
- * __mutex_fastpath_lock_retval() since upon failure of a fastpath
- * lock we want to call our a failure routine with more than one argument, in
- * this case the context for ww mutexes. Refer to commit a41b56ef the
- * argument increase. It'd be painful to backport all asm code for the
- * supported architectures so instead lets penalize the backport ww mutex
- * fastpath lock with the not so efficient generic atomic_dec_return()
- * implementation.
- *
- * Change the count from 1 to a value lower than 1. This function returns 0
- * if the fastpath succeeds, or -1 otherwise.
- */
-static inline int
-__backport_mutex_fastpath_lock_retval(atomic_t *count)
-{
- if (unlikely(atomic_dec_return(count) < 0))
- return -1;
- return 0;
-}
-
-int __sched
-__ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
-{
- int ret;
-
- might_sleep();
-
- ret = __backport_mutex_fastpath_lock_retval(&lock->base.count);
-
- if (likely(!ret)) {
- ww_mutex_set_context_fastpath(lock, ctx);
- mutex_set_owner(&lock->base);
- } else
- ret = __ww_mutex_lock_slowpath(lock, ctx);
- return ret;
-}
-EXPORT_SYMBOL_GPL(__ww_mutex_lock);
-
-int __sched
-__ww_mutex_lock_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
-{
- int ret;
-
- might_sleep();
-
- ret = __backport_mutex_fastpath_lock_retval(&lock->base.count);
-
- if (likely(!ret)) {
- ww_mutex_set_context_fastpath(lock, ctx);
- mutex_set_owner(&lock->base);
- } else
- ret = __ww_mutex_lock_interruptible_slowpath(lock, ctx);
- return ret;
-}
-EXPORT_SYMBOL_GPL(__ww_mutex_lock_interruptible);
projects / openwrt / staging / blogic.git / commitdiff