locking/mutex: Test for initialized mutex
An uninitialized/ zeroed mutex will go unnoticed because there is no check for it. There is a magic check in the unlock's slowpath path which might go unnoticed if the unlock happens in the fastpath. Add a ->magic check early in the mutex_lock() and mutex_trylock() path. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Will Deacon <will@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/20190703092125.lsdf4gpsh2plhavb@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
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@ -908,6 +908,10 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
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might_sleep();
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#ifdef CONFIG_DEBUG_MUTEXES
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DEBUG_LOCKS_WARN_ON(lock->magic != lock);
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#endif
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ww = container_of(lock, struct ww_mutex, base);
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if (use_ww_ctx && ww_ctx) {
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if (unlikely(ww_ctx == READ_ONCE(ww->ctx)))
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@ -1379,8 +1383,13 @@ __ww_mutex_lock_interruptible_slowpath(struct ww_mutex *lock,
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*/
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int __sched mutex_trylock(struct mutex *lock)
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{
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bool locked = __mutex_trylock(lock);
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bool locked;
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#ifdef CONFIG_DEBUG_MUTEXES
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DEBUG_LOCKS_WARN_ON(lock->magic != lock);
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#endif
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locked = __mutex_trylock(lock);
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if (locked)
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mutex_acquire(&lock->dep_map, 0, 1, _RET_IP_);
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