1 files changed, 352 insertions, 32 deletions

diff --git a/kernel/mutex.c b/kernel/mutex.c
index ad53a664f113..e581ada5faf4 100644
--- a/kernel/mutex.c
+++ b/kernel/mutex.c
@@ -254,16 +254,165 @@ void __sched mutex_unlock(struct mutex *lock)
 
 EXPORT_SYMBOL(mutex_unlock);
 
+/**
+ * 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) {
+#ifdef CONFIG_DEBUG_MUTEXES
+                DEBUG_LOCKS_WARN_ON(!lock->ctx->acquired);
+#endif
+                if (lock->ctx->acquired > 0)
+                        lock->ctx->acquired--;
+                lock->ctx = NULL;
+        }
+
+#ifndef CONFIG_DEBUG_MUTEXES
+        /*
+         * When debugging is enabled we must not clear the owner before time,
+         * the slow path will always be taken, and that clears the owner field
+         * after verifying that it was indeed current.
+         */
+        mutex_clear_owner(&lock->base);
+#endif
+        __mutex_fastpath_unlock(&lock->base.count, __mutex_unlock_slowpath);
+}
+EXPORT_SYMBOL(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)) {
+#ifdef CONFIG_DEBUG_MUTEXES
+                DEBUG_LOCKS_WARN_ON(ctx->contending_lock);
+                ctx->contending_lock = ww;
+#endif
+                return -EDEADLK;
+        }
+
+        return 0;
+}
+
+static __always_inline void ww_mutex_lock_acquired(struct ww_mutex *ww,
+                                                   struct ww_acquire_ctx *ww_ctx)
+{
+#ifdef CONFIG_DEBUG_MUTEXES
+        /*
+         * If this WARN_ON triggers, you used ww_mutex_lock to acquire,
+         * but released with a normal mutex_unlock in this call.
+         *
+         * This should never happen, always use ww_mutex_unlock.
+         */
+        DEBUG_LOCKS_WARN_ON(ww->ctx);
+
+        /*
+         * Not quite done after calling ww_acquire_done() ?
+         */
+        DEBUG_LOCKS_WARN_ON(ww_ctx->done_acquire);
+
+        if (ww_ctx->contending_lock) {
+                /*
+                 * After -EDEADLK you tried to
+                 * acquire a different ww_mutex? Bad!
+                 */
+                DEBUG_LOCKS_WARN_ON(ww_ctx->contending_lock != ww);
+
+                /*
+                 * You called ww_mutex_lock after receiving -EDEADLK,
+                 * but 'forgot' to unlock everything else first?
+                 */
+                DEBUG_LOCKS_WARN_ON(ww_ctx->acquired > 0);
+                ww_ctx->contending_lock = NULL;
+        }
+
+        /*
+         * Naughty, using a different class will lead to undefined behavior!
+         */
+        DEBUG_LOCKS_WARN_ON(ww_ctx->ww_class != ww->ww_class);
+#endif
+        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);
+}
+
 /*
  * Lock a mutex (possibly interruptible), slowpath:
  */
-static inline int __sched
+static __always_inline int __sched
 __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
-                    struct lockdep_map *nest_lock, unsigned long ip)
+                    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);
@@ -298,6 +447,22 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
                 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.
@@ -312,6 +477,13 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
                 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();
@@ -371,15 +543,16 @@ slowpath:
                  * TASK_UNINTERRUPTIBLE case.)
                  */
                 if (unlikely(signal_pending_state(state, task))) {
-                        mutex_remove_waiter(lock, &waiter,
-                                            task_thread_info(task));
-                        mutex_release(&lock->dep_map, 1, ip);
-                        spin_unlock_mutex(&lock->wait_lock, flags);
+                        ret = -EINTR;
+                        goto err;
+                }
 
-                        debug_mutex_free_waiter(&waiter);
-                        preempt_enable();
-                        return -EINTR;
+                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: */
@@ -394,6 +567,30 @@ done:
         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);
@@ -404,6 +601,14 @@ done:
         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;
 }
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
@@ -411,7 +616,8 @@ void __sched
 mutex_lock_nested(struct mutex *lock, unsigned int subclass)
 {
         might_sleep();
-        __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, subclass, NULL, _RET_IP_);
+        __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE,
+                            subclass, NULL, _RET_IP_, NULL);
 }
 
 EXPORT_SYMBOL_GPL(mutex_lock_nested);
@@ -420,7 +626,8 @@ void __sched
 _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest)
 {
         might_sleep();
-        __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0, nest, _RET_IP_);
+        __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE,
+                            0, nest, _RET_IP_, NULL);
 }
 
 EXPORT_SYMBOL_GPL(_mutex_lock_nest_lock);
@@ -429,7 +636,8 @@ int __sched
 mutex_lock_killable_nested(struct mutex *lock, unsigned int subclass)
 {
         might_sleep();
-        return __mutex_lock_common(lock, TASK_KILLABLE, subclass, NULL, _RET_IP_);
+        return __mutex_lock_common(lock, TASK_KILLABLE,
+                                   subclass, NULL, _RET_IP_, NULL);
 }
 EXPORT_SYMBOL_GPL(mutex_lock_killable_nested);
 
@@ -438,10 +646,68 @@ mutex_lock_interruptible_nested(struct mutex *lock, unsigned int subclass)
 {
         might_sleep();
         return __mutex_lock_common(lock, TASK_INTERRUPTIBLE,
-                                   subclass, NULL, _RET_IP_);
+                                   subclass, NULL, _RET_IP_, NULL);
 }
 
 EXPORT_SYMBOL_GPL(mutex_lock_interruptible_nested);
+
+static inline int
+ww_mutex_deadlock_injection(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
+{
+#ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH
+        unsigned tmp;
+
+        if (ctx->deadlock_inject_countdown-- == 0) {
+                tmp = ctx->deadlock_inject_interval;
+                if (tmp > UINT_MAX/4)
+                        tmp = UINT_MAX;
+                else
+                        tmp = tmp*2 + tmp + tmp/2;
+
+                ctx->deadlock_inject_interval = tmp;
+                ctx->deadlock_inject_countdown = tmp;
+                ctx->contending_lock = lock;
+
+                ww_mutex_unlock(lock);
+
+                return -EDEADLK;
+        }
+#endif
+
+        return 0;
+}
+
+int __sched
+__ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
+{
+        int ret;
+
+        might_sleep();
+        ret =  __mutex_lock_common(&lock->base, TASK_UNINTERRUPTIBLE,
+                                   0, &ctx->dep_map, _RET_IP_, ctx);
+        if (!ret && ctx->acquired > 0)
+                return ww_mutex_deadlock_injection(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 = __mutex_lock_common(&lock->base, TASK_INTERRUPTIBLE,
+                                  0, &ctx->dep_map, _RET_IP_, ctx);
+
+        if (!ret && ctx->acquired > 0)
+                return ww_mutex_deadlock_injection(lock, ctx);
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(__ww_mutex_lock_interruptible);
+
 #endif
 
 /*
@@ -494,10 +760,10 @@ __mutex_unlock_slowpath(atomic_t *lock_count)
  * mutex_lock_interruptible() and mutex_trylock().
  */
 static noinline int __sched
-__mutex_lock_killable_slowpath(atomic_t *lock_count);
+__mutex_lock_killable_slowpath(struct mutex *lock);
 
 static noinline int __sched
-__mutex_lock_interruptible_slowpath(atomic_t *lock_count);
+__mutex_lock_interruptible_slowpath(struct mutex *lock);
 
 /**
  * mutex_lock_interruptible - acquire the mutex, interruptible
@@ -515,12 +781,12 @@ int __sched mutex_lock_interruptible(struct mutex *lock)
         int ret;
 
         might_sleep();
-        ret =  __mutex_fastpath_lock_retval
-                        (&lock->count, __mutex_lock_interruptible_slowpath);
-        if (!ret)
+        ret =  __mutex_fastpath_lock_retval(&lock->count);
+        if (likely(!ret)) {
                 mutex_set_owner(lock);
-
-        return ret;
+                return 0;
+        } else
+                return __mutex_lock_interruptible_slowpath(lock);
 }
 
 EXPORT_SYMBOL(mutex_lock_interruptible);
@@ -530,12 +796,12 @@ int __sched mutex_lock_killable(struct mutex *lock)
         int ret;
 
         might_sleep();
-        ret = __mutex_fastpath_lock_retval
-                        (&lock->count, __mutex_lock_killable_slowpath);
-        if (!ret)
+        ret = __mutex_fastpath_lock_retval(&lock->count);
+        if (likely(!ret)) {
                 mutex_set_owner(lock);
-
-        return ret;
+                return 0;
+        } else
+                return __mutex_lock_killable_slowpath(lock);
 }
 EXPORT_SYMBOL(mutex_lock_killable);
 
@@ -544,24 +810,39 @@ __mutex_lock_slowpath(atomic_t *lock_count)
 {
         struct mutex *lock = container_of(lock_count, struct mutex, count);
 
-        __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0, NULL, _RET_IP_);
+        __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0,
+                            NULL, _RET_IP_, NULL);
 }
 
 static noinline int __sched
-__mutex_lock_killable_slowpath(atomic_t *lock_count)
+__mutex_lock_killable_slowpath(struct mutex *lock)
 {
-        struct mutex *lock = container_of(lock_count, struct mutex, count);
+        return __mutex_lock_common(lock, TASK_KILLABLE, 0,
+                                   NULL, _RET_IP_, NULL);
+}
 
-        return __mutex_lock_common(lock, TASK_KILLABLE, 0, NULL, _RET_IP_);
+static noinline int __sched
+__mutex_lock_interruptible_slowpath(struct mutex *lock)
+{
+        return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, 0,
+                                   NULL, _RET_IP_, NULL);
 }
 
 static noinline int __sched
-__mutex_lock_interruptible_slowpath(atomic_t *lock_count)
+__ww_mutex_lock_slowpath(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
 {
-        struct mutex *lock = container_of(lock_count, struct mutex, count);
+        return __mutex_lock_common(&lock->base, TASK_UNINTERRUPTIBLE, 0,
+                                   NULL, _RET_IP_, ctx);
+}
 
-        return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, 0, NULL, _RET_IP_);
+static noinline int __sched
+__ww_mutex_lock_interruptible_slowpath(struct ww_mutex *lock,
+                                            struct ww_acquire_ctx *ctx)
+{
+        return __mutex_lock_common(&lock->base, TASK_INTERRUPTIBLE, 0,
+                                   NULL, _RET_IP_, ctx);
 }
+
 #endif
 
 /*
@@ -617,6 +898,45 @@ int __sched mutex_trylock(struct mutex *lock)
 }
 EXPORT_SYMBOL(mutex_trylock);
 
+#ifndef CONFIG_DEBUG_LOCK_ALLOC
+int __sched
+__ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
+{
+        int ret;
+
+        might_sleep();
+
+        ret = __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(__ww_mutex_lock);
+
+int __sched
+__ww_mutex_lock_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
+{
+        int ret;
+
+        might_sleep();
+
+        ret = __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(__ww_mutex_lock_interruptible);
+
+#endif
+
 /**
  * atomic_dec_and_mutex_lock - return holding mutex if we dec to 0
  * @cnt: the atomic which we are to dec