Merge branch 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

Pull core/locking changes from Ingo Molnar:
 "Main changes:

   - another mutex optimization, from Davidlohr Bueso

   - improved lglock lockdep tracking, from Michel Lespinasse

   - [ assorted smaller updates, improvements, cleanups. ]"

* 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  generic-ipi/locking: Fix misleading smp_call_function_any() description
  hung_task debugging: Print more info when reporting the problem
  mutex: Avoid label warning when !CONFIG_MUTEX_SPIN_ON_OWNER
  mutex: Do not unnecessarily deal with waiters
  mutex: Fix/document access-once assumption in mutex_can_spin_on_owner()
  lglock: Update lockdep annotations to report recursive local locks
  lockdep: Introduce lock_acquire_exclusive()/shared() helper macros

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index f1e877b79ed8c1f078db76daa94c207172abba22..cfc2f119779ab6a202082b42ba58d0fb6290f676 100644 (file)
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -365,7 +365,7 @@ extern void lockdep_trace_alloc(gfp_t mask);
 
 #define lockdep_recursing(tsk) ((tsk)->lockdep_recursion)
 
-#else /* !LOCKDEP */
+#else /* !CONFIG_LOCKDEP */
 
 static inline void lockdep_off(void)
 {
@@ -479,82 +479,36 @@ static inline void print_irqtrace_events(struct task_struct *curr)
  * on the per lock-class debug mode:
  */
 
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-# ifdef CONFIG_PROVE_LOCKING
-#  define spin_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 2, NULL, i)
-#  define spin_acquire_nest(l, s, t, n, i)     lock_acquire(l, s, t, 0, 2, n, i)
-# else
-#  define spin_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 1, NULL, i)
-#  define spin_acquire_nest(l, s, t, n, i)     lock_acquire(l, s, t, 0, 1, NULL, i)
-# endif
-# define spin_release(l, n, i)                 lock_release(l, n, i)
+#ifdef CONFIG_PROVE_LOCKING
+ #define lock_acquire_exclusive(l, s, t, n, i)         lock_acquire(l, s, t, 0, 2, n, i)
+ #define lock_acquire_shared(l, s, t, n, i)            lock_acquire(l, s, t, 1, 2, n, i)
+ #define lock_acquire_shared_recursive(l, s, t, n, i)  lock_acquire(l, s, t, 2, 2, n, i)
 #else
-# define spin_acquire(l, s, t, i)              do { } while (0)
-# define spin_release(l, n, i)                 do { } while (0)
+ #define lock_acquire_exclusive(l, s, t, n, i)         lock_acquire(l, s, t, 0, 1, n, i)
+ #define lock_acquire_shared(l, s, t, n, i)            lock_acquire(l, s, t, 1, 1, n, i)
+ #define lock_acquire_shared_recursive(l, s, t, n, i)  lock_acquire(l, s, t, 2, 1, n, i)
 #endif
 
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-# ifdef CONFIG_PROVE_LOCKING
-#  define rwlock_acquire(l, s, t, i)           lock_acquire(l, s, t, 0, 2, NULL, i)
-#  define rwlock_acquire_read(l, s, t, i)      lock_acquire(l, s, t, 2, 2, NULL, i)
-# else
-#  define rwlock_acquire(l, s, t, i)           lock_acquire(l, s, t, 0, 1, NULL, i)
-#  define rwlock_acquire_read(l, s, t, i)      lock_acquire(l, s, t, 2, 1, NULL, i)
-# endif
-# define rwlock_release(l, n, i)               lock_release(l, n, i)
-#else
-# define rwlock_acquire(l, s, t, i)            do { } while (0)
-# define rwlock_acquire_read(l, s, t, i)       do { } while (0)
-# define rwlock_release(l, n, i)               do { } while (0)
-#endif
+#define spin_acquire(l, s, t, i)               lock_acquire_exclusive(l, s, t, NULL, i)
+#define spin_acquire_nest(l, s, t, n, i)       lock_acquire_exclusive(l, s, t, n, i)
+#define spin_release(l, n, i)                  lock_release(l, n, i)
 
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-# ifdef CONFIG_PROVE_LOCKING
-#  define mutex_acquire(l, s, t, i)            lock_acquire(l, s, t, 0, 2, NULL, i)
-#  define mutex_acquire_nest(l, s, t, n, i)    lock_acquire(l, s, t, 0, 2, n, i)
-# else
-#  define mutex_acquire(l, s, t, i)            lock_acquire(l, s, t, 0, 1, NULL, i)
-#  define mutex_acquire_nest(l, s, t, n, i)    lock_acquire(l, s, t, 0, 1, n, i)
-# endif
-# define mutex_release(l, n, i)                        lock_release(l, n, i)
-#else
-# define mutex_acquire(l, s, t, i)             do { } while (0)
-# define mutex_acquire_nest(l, s, t, n, i)     do { } while (0)
-# define mutex_release(l, n, i)                        do { } while (0)
-#endif
+#define rwlock_acquire(l, s, t, i)             lock_acquire_exclusive(l, s, t, NULL, i)
+#define rwlock_acquire_read(l, s, t, i)                lock_acquire_shared_recursive(l, s, t, NULL, i)
+#define rwlock_release(l, n, i)                        lock_release(l, n, i)
 
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-# ifdef CONFIG_PROVE_LOCKING
-#  define rwsem_acquire(l, s, t, i)            lock_acquire(l, s, t, 0, 2, NULL, i)
-#  define rwsem_acquire_nest(l, s, t, n, i)    lock_acquire(l, s, t, 0, 2, n, i)
-#  define rwsem_acquire_read(l, s, t, i)       lock_acquire(l, s, t, 1, 2, NULL, i)
-# else
-#  define rwsem_acquire(l, s, t, i)            lock_acquire(l, s, t, 0, 1, NULL, i)
-#  define rwsem_acquire_nest(l, s, t, n, i)    lock_acquire(l, s, t, 0, 1, n, i)
-#  define rwsem_acquire_read(l, s, t, i)       lock_acquire(l, s, t, 1, 1, NULL, i)
-# endif
+#define mutex_acquire(l, s, t, i)              lock_acquire_exclusive(l, s, t, NULL, i)
+#define mutex_acquire_nest(l, s, t, n, i)      lock_acquire_exclusive(l, s, t, n, i)
+#define mutex_release(l, n, i)                 lock_release(l, n, i)
+
+#define rwsem_acquire(l, s, t, i)              lock_acquire_exclusive(l, s, t, NULL, i)
+#define rwsem_acquire_nest(l, s, t, n, i)      lock_acquire_exclusive(l, s, t, n, i)
+#define rwsem_acquire_read(l, s, t, i)         lock_acquire_shared(l, s, t, NULL, i)
 # define rwsem_release(l, n, i)                        lock_release(l, n, i)
-#else
-# define rwsem_acquire(l, s, t, i)             do { } while (0)
-# define rwsem_acquire_nest(l, s, t, n, i)     do { } while (0)
-# define rwsem_acquire_read(l, s, t, i)                do { } while (0)
-# define rwsem_release(l, n, i)                        do { } while (0)
-#endif
 
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-# ifdef CONFIG_PROVE_LOCKING
-#  define lock_map_acquire(l)          lock_acquire(l, 0, 0, 0, 2, NULL, _THIS_IP_)
-#  define lock_map_acquire_read(l)     lock_acquire(l, 0, 0, 2, 2, NULL, _THIS_IP_)
-# else
-#  define lock_map_acquire(l)          lock_acquire(l, 0, 0, 0, 1, NULL, _THIS_IP_)
-#  define lock_map_acquire_read(l)     lock_acquire(l, 0, 0, 2, 1, NULL, _THIS_IP_)
-# endif
+#define lock_map_acquire(l)                    lock_acquire_exclusive(l, 0, 0, NULL, _THIS_IP_)
+#define lock_map_acquire_read(l)               lock_acquire_shared_recursive(l, 0, 0, NULL, _THIS_IP_)
 # define lock_map_release(l)                   lock_release(l, 1, _THIS_IP_)
-#else
-# define lock_map_acquire(l)                   do { } while (0)
-# define lock_map_acquire_read(l)              do { } while (0)
-# define lock_map_release(l)                   do { } while (0)
-#endif
 
 #ifdef CONFIG_PROVE_LOCKING
 # define might_lock(lock)                                              \

diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index 6df614912b9d40a9f77dd4fadc54af4fa1ca3ccb..3e97fb126e6b9255a852887923f39230cd52c513 100644 (file)
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -15,6 +15,7 @@
 #include <linux/lockdep.h>
 #include <linux/export.h>
 #include <linux/sysctl.h>
+#include <linux/utsname.h>
 
 /*
  * The number of tasks checked:
@@ -99,10 +100,14 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
         * Ok, the task did not get scheduled for more than 2 minutes,
         * complain:
         */
-       printk(KERN_ERR "INFO: task %s:%d blocked for more than "
-                       "%ld seconds.\n", t->comm, t->pid, timeout);
-       printk(KERN_ERR "\"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\""
-                       " disables this message.\n");
+       pr_err("INFO: task %s:%d blocked for more than %ld seconds.\n",
+               t->comm, t->pid, timeout);
+       pr_err("      %s %s %.*s\n",
+               print_tainted(), init_utsname()->release,
+               (int)strcspn(init_utsname()->version, " "),
+               init_utsname()->version);
+       pr_err("\"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\""
+               " disables this message.\n");
        sched_show_task(t);
        debug_show_held_locks(t);
 

diff --git a/kernel/lglock.c b/kernel/lglock.c
index 6535a667a5a797a3fa1f9a9683cd9e85124692d7..86ae2aebf00432f4d681a413febebff79406889d 100644 (file)
--- a/kernel/lglock.c
+++ b/kernel/lglock.c
@@ -21,7 +21,7 @@ void lg_local_lock(struct lglock *lg)
        arch_spinlock_t *lock;
 
        preempt_disable();
-       rwlock_acquire_read(&lg->lock_dep_map, 0, 0, _RET_IP_);
+       lock_acquire_shared(&lg->lock_dep_map, 0, 0, NULL, _RET_IP_);
        lock = this_cpu_ptr(lg->lock);
        arch_spin_lock(lock);
 }
@@ -31,7 +31,7 @@ void lg_local_unlock(struct lglock *lg)
 {
        arch_spinlock_t *lock;
 
-       rwlock_release(&lg->lock_dep_map, 1, _RET_IP_);
+       lock_release(&lg->lock_dep_map, 1, _RET_IP_);
        lock = this_cpu_ptr(lg->lock);
        arch_spin_unlock(lock);
        preempt_enable();
@@ -43,7 +43,7 @@ void lg_local_lock_cpu(struct lglock *lg, int cpu)
        arch_spinlock_t *lock;
 
        preempt_disable();
-       rwlock_acquire_read(&lg->lock_dep_map, 0, 0, _RET_IP_);
+       lock_acquire_shared(&lg->lock_dep_map, 0, 0, NULL, _RET_IP_);
        lock = per_cpu_ptr(lg->lock, cpu);
        arch_spin_lock(lock);
 }
@@ -53,7 +53,7 @@ void lg_local_unlock_cpu(struct lglock *lg, int cpu)
 {
        arch_spinlock_t *lock;
 
-       rwlock_release(&lg->lock_dep_map, 1, _RET_IP_);
+       lock_release(&lg->lock_dep_map, 1, _RET_IP_);
        lock = per_cpu_ptr(lg->lock, cpu);
        arch_spin_unlock(lock);
        preempt_enable();
@@ -65,7 +65,7 @@ void lg_global_lock(struct lglock *lg)
        int i;
 
        preempt_disable();
-       rwlock_acquire(&lg->lock_dep_map, 0, 0, _RET_IP_);
+       lock_acquire_exclusive(&lg->lock_dep_map, 0, 0, NULL, _RET_IP_);
        for_each_possible_cpu(i) {
                arch_spinlock_t *lock;
                lock = per_cpu_ptr(lg->lock, i);
@@ -78,7 +78,7 @@ void lg_global_unlock(struct lglock *lg)
 {
        int i;
 
-       rwlock_release(&lg->lock_dep_map, 1, _RET_IP_);
+       lock_release(&lg->lock_dep_map, 1, _RET_IP_);
        for_each_possible_cpu(i) {
                arch_spinlock_t *lock;
                lock = per_cpu_ptr(lg->lock, i);

diff --git a/kernel/mutex.c b/kernel/mutex.c
index a52ee7bb830d3fa9db3cf898a34c8212664ac8b7..6d647aedffea494dec6b11d20fa222a05fd49f7f 100644 (file)
--- a/kernel/mutex.c
+++ b/kernel/mutex.c
@@ -209,11 +209,13 @@ int mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner)
  */
 static inline int mutex_can_spin_on_owner(struct mutex *lock)
 {
+       struct task_struct *owner;
        int retval = 1;
 
        rcu_read_lock();
-       if (lock->owner)
-               retval = lock->owner->on_cpu;
+       owner = ACCESS_ONCE(lock->owner);
+       if (owner)
+               retval = owner->on_cpu;
        rcu_read_unlock();
        /*
         * if lock->owner is not set, the mutex owner may have just acquired
@@ -461,7 +463,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
                         * performed the optimistic spinning cannot be done.
                         */
                        if (ACCESS_ONCE(ww->ctx))
-                               break;
+                               goto slowpath;
                }
 
                /*
@@ -472,7 +474,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
                owner = ACCESS_ONCE(lock->owner);
                if (owner && !mutex_spin_on_owner(lock, owner)) {
                        mspin_unlock(MLOCK(lock), &node);
-                       break;
+                       goto slowpath;
                }
 
                if ((atomic_read(&lock->count) == 1) &&
@@ -499,7 +501,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
                 * the owner complete.
                 */
                if (!owner && (need_resched() || rt_task(task)))
-                       break;
+                       goto slowpath;
 
                /*
                 * The cpu_relax() call is a compiler barrier which forces
@@ -513,6 +515,10 @@ slowpath:
 #endif
        spin_lock_mutex(&lock->wait_lock, flags);
 
+       /* once more, can we acquire the lock? */
+       if (MUTEX_SHOW_NO_WAITER(lock) && (atomic_xchg(&lock->count, 0) == 1))
+               goto skip_wait;
+
        debug_mutex_lock_common(lock, &waiter);
        debug_mutex_add_waiter(lock, &waiter, task_thread_info(task));
 
@@ -520,9 +526,6 @@ slowpath:
        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 (;;) {
@@ -536,7 +539,7 @@ slowpath:
                 * other waiters:
                 */
                if (MUTEX_SHOW_NO_WAITER(lock) &&
-                  (atomic_xchg(&lock->count, -1) == 1))
+                   (atomic_xchg(&lock->count, -1) == 1))
                        break;
 
                /*
@@ -561,24 +564,25 @@ slowpath:
                schedule_preempt_disabled();
                spin_lock_mutex(&lock->wait_lock, flags);
        }
+       mutex_remove_waiter(lock, &waiter, current_thread_info());
+       /* set it to 0 if there are no waiters left: */
+       if (likely(list_empty(&lock->wait_list)))
+               atomic_set(&lock->count, 0);
+       debug_mutex_free_waiter(&waiter);
 
-done:
+skip_wait:
+       /* got the lock - cleanup and rejoice! */
        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 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;
 
@@ -592,15 +596,8 @@ done:
                }
        }
 
-       /* 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:

diff --git a/kernel/smp.c b/kernel/smp.c
index fe9f773d71146c82ad9c543ab0456490c9bebd0f..b1c9034bdfcb060ca7977a507f6b32dd7f8da1a1 100644 (file)
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -278,8 +278,6 @@ EXPORT_SYMBOL(smp_call_function_single);
  * @wait: If true, wait until function has completed.
  *
  * Returns 0 on success, else a negative status code (if no cpus were online).
- * Note that @wait will be implicitly turned on in case of allocation failures,
- * since we fall back to on-stack allocation.
  *
  * Selection preference:
  *     1) current cpu if in @mask