Alexey Izbyshev 1438d6e9d6 futex: Resend potentially swallowed owner death notification ... [ Upstream commit 90d7588967 ] Commit ca16d5bee5 ("futex: Prevent robust futex exit race") addressed two cases when tasks waiting on a robust non-PI futex remained blocked despite the futex not being owned anymore: * if the owner died after writing zero to the futex word, but before waking up a waiter * if a task waiting on the futex was woken up, but died before updating the futex word (effectively swallowing the notification without acting on it) In the second case, the task could be woken up either by the previous owner (after the futex word was reset to zero) or by the kernel (after the OWNER_DIED bit was set and the TID part of the futex word was reset to zero) if the previous owner died without the resetting the futex. Because the referenced commit wakes up a potential waiter only if the whole futex word is zero, the latter subcase remains unaddressed. Fix this by looking only at the TID part of the futex when deciding whether a wake up is needed. Fixes: ca16d5bee5 ("futex: Prevent robust futex exit race") Signed-off-by: Alexey Izbyshev <izbyshev@ispras.ru> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20221111215439.248185-1-izbyshev@ispras.ru Signed-off-by: Sasha Levin <sashal@kernel.org>		2022-12-31 13:25:45 +01:00
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core.c	futex: Resend potentially swallowed owner death notification	2022-12-31 13:25:45 +01:00
futex.h	futex: add missing rtmutex.h include	2022-04-07 15:09:12 +02:00
Makefile	futex: Split out wait/wake	2021-10-07 13:51:11 +02:00
pi.c	futex: Remove a PREEMPT_RT_FULL reference.	2022-05-13 12:36:51 +02:00
requeue.c	futex: Split out requeue	2021-10-07 13:51:10 +02:00
syscalls.c	futex: Remove futex_cmpxchg detection	2021-11-25 00:02:28 +01:00
waitwake.c	futex: Implement sys_futex_waitv()	2021-10-07 13:51:11 +02:00