diff options
| -rw-r--r-- | include/linux/mutex.h | 2 | ||||
| -rw-r--r-- | include/linux/sched.h | 2 | ||||
| -rw-r--r-- | kernel/mutex-debug.c | 2 | ||||
| -rw-r--r-- | kernel/mutex-debug.h | 2 | ||||
| -rw-r--r-- | kernel/mutex.c | 2 | ||||
| -rw-r--r-- | kernel/mutex.h | 2 | ||||
| -rw-r--r-- | kernel/sched.c | 83 |
7 files changed, 39 insertions, 56 deletions
diff --git a/include/linux/mutex.h b/include/linux/mutex.h index 94b48bd40dd7..c75471db576e 100644 --- a/include/linux/mutex.h +++ b/include/linux/mutex.h @@ -51,7 +51,7 @@ struct mutex { spinlock_t wait_lock; struct list_head wait_list; #if defined(CONFIG_DEBUG_MUTEXES) || defined(CONFIG_SMP) - struct thread_info *owner; + struct task_struct *owner; #endif #ifdef CONFIG_DEBUG_MUTEXES const char *name; diff --git a/include/linux/sched.h b/include/linux/sched.h index 3435837e89ff..173850479e2c 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -360,7 +360,7 @@ extern signed long schedule_timeout_interruptible(signed long timeout); extern signed long schedule_timeout_killable(signed long timeout); extern signed long schedule_timeout_uninterruptible(signed long timeout); asmlinkage void schedule(void); -extern int mutex_spin_on_owner(struct mutex *lock, struct thread_info *owner); +extern int mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner); struct nsproxy; struct user_namespace; diff --git a/kernel/mutex-debug.c b/kernel/mutex-debug.c index ec815a960b5d..73da83aff418 100644 --- a/kernel/mutex-debug.c +++ b/kernel/mutex-debug.c @@ -75,7 +75,7 @@ void debug_mutex_unlock(struct mutex *lock) return; DEBUG_LOCKS_WARN_ON(lock->magic != lock); - DEBUG_LOCKS_WARN_ON(lock->owner != current_thread_info()); + DEBUG_LOCKS_WARN_ON(lock->owner != current); DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next); mutex_clear_owner(lock); } diff --git a/kernel/mutex-debug.h b/kernel/mutex-debug.h index 57d527a16f9d..0799fd3e4cfa 100644 --- a/kernel/mutex-debug.h +++ b/kernel/mutex-debug.h @@ -29,7 +29,7 @@ extern void debug_mutex_init(struct mutex *lock, const char *name, static inline void mutex_set_owner(struct mutex *lock) { - lock->owner = current_thread_info(); + lock->owner = current; } static inline void mutex_clear_owner(struct mutex *lock) diff --git a/kernel/mutex.c b/kernel/mutex.c index c4195fa98900..fe4706cb0c5b 100644 --- a/kernel/mutex.c +++ b/kernel/mutex.c @@ -160,7 +160,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, */ for (;;) { - struct thread_info *owner; + struct task_struct *owner; /* * If we own the BKL, then don't spin. The owner of diff --git a/kernel/mutex.h b/kernel/mutex.h index 67578ca48f94..4115fbf83b12 100644 --- a/kernel/mutex.h +++ b/kernel/mutex.h @@ -19,7 +19,7 @@ #ifdef CONFIG_SMP static inline void mutex_set_owner(struct mutex *lock) { - lock->owner = current_thread_info(); + lock->owner = current; } static inline void mutex_clear_owner(struct mutex *lock) diff --git a/kernel/sched.c b/kernel/sched.c index cd2593e1a3ec..55cc50323ce1 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -4173,70 +4173,53 @@ need_resched: EXPORT_SYMBOL(schedule); #ifdef CONFIG_MUTEX_SPIN_ON_OWNER -/* - * Look out! "owner" is an entirely speculative pointer - * access and not reliable. - */ -int mutex_spin_on_owner(struct mutex *lock, struct thread_info *owner) -{ - unsigned int cpu; - struct rq *rq; - if (!sched_feat(OWNER_SPIN)) - return 0; +static inline bool owner_running(struct mutex *lock, struct task_struct *owner) +{ + bool ret = false; -#ifdef CONFIG_DEBUG_PAGEALLOC - /* - * Need to access the cpu field knowing that - * DEBUG_PAGEALLOC could have unmapped it if - * the mutex owner just released it and exited. - */ - if (probe_kernel_address(&owner->cpu, cpu)) - return 0; -#else - cpu = owner->cpu; -#endif + rcu_read_lock(); + if (lock->owner != owner) + goto fail; /* - * Even if the access succeeded (likely case), - * the cpu field may no longer be valid. + * 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. */ - if (cpu >= nr_cpumask_bits) - return 0; + barrier(); - /* - * We need to validate that we can do a - * get_cpu() and that we have the percpu area. - */ - if (!cpu_online(cpu)) - return 0; + ret = owner->on_cpu; +fail: + rcu_read_unlock(); - rq = cpu_rq(cpu); + return ret; +} - for (;;) { - /* - * Owner changed, break to re-assess state. - */ - if (lock->owner != owner) { - /* - * If the lock has switched to a different owner, - * we likely have heavy contention. Return 0 to quit - * optimistic spinning and not contend further: - */ - if (lock->owner) - return 0; - break; - } +/* + * Look out! "owner" is an entirely speculative pointer + * access and not reliable. + */ +int mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner) +{ + if (!sched_feat(OWNER_SPIN)) + return 0; - /* - * Is that owner really running on that cpu? - */ - if (task_thread_info(rq->curr) != owner || need_resched()) + while (owner_running(lock, owner)) { + if (need_resched()) return 0; arch_mutex_cpu_relax(); } + /* + * If the owner changed to another task there is likely + * heavy contention, stop spinning. + */ + if (lock->owner) + return 0; + return 1; } #endif |