locking: ww_mutex: fix ww_mutex vs self-deadlock
If the caller already holds the mutex, task_blocks_on_rt_mutex() returns -EDEADLK, we proceed directly to rt_mutex_handle_deadlock() where it's instant game over. Let ww_mutexes return EDEADLK/EALREADY as they want to instead. Cc: stable-rt@vger.kernel.org Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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@ -1694,13 +1694,20 @@ rt_mutex_slowlock(struct rt_mutex *lock, int state,
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if (likely(!ret))
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ret = __rt_mutex_slowlock(lock, state, timeout, &waiter, ww_ctx);
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else if (ww_ctx) {
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/* ww_mutex received EDEADLK, let it become EALREADY */
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ret = __mutex_lock_check_stamp(lock, ww_ctx);
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BUG_ON(!ret);
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}
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set_current_state(TASK_RUNNING);
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if (unlikely(ret)) {
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if (rt_mutex_has_waiters(lock))
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remove_waiter(lock, &waiter);
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rt_mutex_handle_deadlock(ret, chwalk, &waiter);
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/* ww_mutex want to report EDEADLK/EALREADY, let them */
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if (!ww_ctx)
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rt_mutex_handle_deadlock(ret, chwalk, &waiter);
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} else if (ww_ctx) {
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ww_mutex_account_lock(lock, ww_ctx);
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}
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@ -2239,8 +2246,7 @@ __ww_mutex_lock_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ww_c
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might_sleep();
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mutex_acquire_nest(&lock->base.dep_map, 0, 0, &ww_ctx->dep_map, _RET_IP_);
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ret = rt_mutex_slowlock(&lock->base.lock, TASK_INTERRUPTIBLE, NULL,
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RT_MUTEX_FULL_CHAINWALK, ww_ctx);
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ret = rt_mutex_slowlock(&lock->base.lock, TASK_INTERRUPTIBLE, NULL, 0, ww_ctx);
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if (ret)
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mutex_release(&lock->base.dep_map, 1, _RET_IP_);
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else if (!ret && ww_ctx->acquired > 1)
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@ -2258,8 +2264,7 @@ __ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ww_ctx)
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might_sleep();
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mutex_acquire_nest(&lock->base.dep_map, 0, 0, &ww_ctx->dep_map, _RET_IP_);
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ret = rt_mutex_slowlock(&lock->base.lock, TASK_UNINTERRUPTIBLE, NULL,
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RT_MUTEX_FULL_CHAINWALK, ww_ctx);
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ret = rt_mutex_slowlock(&lock->base.lock, TASK_UNINTERRUPTIBLE, NULL, 0, ww_ctx);
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if (ret)
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mutex_release(&lock->base.dep_map, 1, _RET_IP_);
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else if (!ret && ww_ctx->acquired > 1)
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@ -2271,11 +2276,13 @@ EXPORT_SYMBOL_GPL(__ww_mutex_lock);
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void __sched ww_mutex_unlock(struct ww_mutex *lock)
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{
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int nest = !!lock->ctx;
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/*
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* The unlocking fastpath is the 0->1 transition from 'locked'
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* into 'unlocked' state:
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*/
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if (lock->ctx) {
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if (nest) {
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#ifdef CONFIG_DEBUG_MUTEXES
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DEBUG_LOCKS_WARN_ON(!lock->ctx->acquired);
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#endif
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@ -2284,7 +2291,7 @@ void __sched ww_mutex_unlock(struct ww_mutex *lock)
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lock->ctx = NULL;
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}
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mutex_release(&lock->base.dep_map, 1, _RET_IP_);
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mutex_release(&lock->base.dep_map, nest, _RET_IP_);
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rt_mutex_unlock(&lock->base.lock);
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}
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EXPORT_SYMBOL(ww_mutex_unlock);
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