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author | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2019-06-26 17:44:18 +0200 |
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committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2019-07-23 14:57:13 -0400 |
commit | fc4135e260f6da91eb07729be79a538b2c0b0142 (patch) | |
tree | 9557fa50af675d3dbf6ebc05c33d1d36b5add1aa /kernel/locking/rtmutex.c | |
parent | 34d18476fc4e824d6eaba6fd5d3b876c9477dd14 (diff) |
Revert "futex: Fix bug on when a requeued RT task times out"
[ Upstream commit f1a170cb3289a48df26cae3c60d77608f7a988bb ]
Drop the RT fixup, the futex code will be changed to avoid the need for
the workaround.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/locking/rtmutex.c')
-rw-r--r-- | kernel/locking/rtmutex.c | 31 |
1 files changed, 1 insertions, 30 deletions
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c index 2a9bf2443acc..7f6f402e04ae 100644 --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -144,8 +144,7 @@ static void fixup_rt_mutex_waiters(struct rt_mutex *lock) static int rt_mutex_real_waiter(struct rt_mutex_waiter *waiter) { - return waiter && waiter != PI_WAKEUP_INPROGRESS && - waiter != PI_REQUEUE_INPROGRESS; + return waiter && waiter != PI_WAKEUP_INPROGRESS; } /* @@ -2350,34 +2349,6 @@ int __rt_mutex_start_proxy_lock(struct rt_mutex *lock, if (try_to_take_rt_mutex(lock, task, NULL)) return 1; -#ifdef CONFIG_PREEMPT_RT_FULL - /* - * In PREEMPT_RT there's an added race. - * If the task, that we are about to requeue, times out, - * it can set the PI_WAKEUP_INPROGRESS. This tells the requeue - * to skip this task. But right after the task sets - * its pi_blocked_on to PI_WAKEUP_INPROGRESS it can then - * block on the spin_lock(&hb->lock), which in RT is an rtmutex. - * This will replace the PI_WAKEUP_INPROGRESS with the actual - * lock that it blocks on. We *must not* place this task - * on this proxy lock in that case. - * - * To prevent this race, we first take the task's pi_lock - * and check if it has updated its pi_blocked_on. If it has, - * we assume that it woke up and we return -EAGAIN. - * Otherwise, we set the task's pi_blocked_on to - * PI_REQUEUE_INPROGRESS, so that if the task is waking up - * it will know that we are in the process of requeuing it. - */ - raw_spin_lock(&task->pi_lock); - if (task->pi_blocked_on) { - raw_spin_unlock(&task->pi_lock); - return -EAGAIN; - } - task->pi_blocked_on = PI_REQUEUE_INPROGRESS; - raw_spin_unlock(&task->pi_lock); -#endif - /* We enforce deadlock detection for futexes */ ret = task_blocks_on_rt_mutex(lock, waiter, task, RT_MUTEX_FULL_CHAINWALK); |