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monitor: don't wake up qmp_dispatcher_co coroutine upon cleanup

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Since the commit 3e6bed61 ("monitor: cleanup detection of qmp_dispatcher_co
shutting down"), coroutine pointer qmp_dispatcher_co is set to NULL upon
cleanup.  If a QMP command is sent after monitor_cleanup() (e.g. after
shutdown), this may lead to SEGFAULT on aio_co_wake(NULL).

As mentioned in the comment inside monitor_cleanup(), the intention is to
allow incoming requests while shutting down, but simply leave them
without any response.  Let's do exactly that, and if qmp_dispatcher_co
coroutine pointer has already been set to NULL, let's simply skip the
aio_co_wake() part.

Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
Link: https://lore.kernel.org/r/20250502214729.928380-2-andrey.drobyshev@virtuozzo.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Andrey Drobyshev 2025-05-03 00:47:29 +03:00 • committed by Paolo Bonzini
parent ffd5a60e9b
commit 03f50d7ee7
1 changed files with 2 additions and 1 deletions
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3
monitor/qmp.c
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@ -356,7 +356,8 @@ void qmp_dispatcher_co_wake(void)
/* Write request before reading qmp_dispatcher_co_busy. */ /* Write request before reading qmp_dispatcher_co_busy. */
smp_mb__before_rmw(); smp_mb__before_rmw();
if (!qatomic_xchg(&qmp_dispatcher_co_busy, true)) { if (!qatomic_xchg(&qmp_dispatcher_co_busy, true) &&
qatomic_read(&qmp_dispatcher_co)) {
aio_co_wake(qmp_dispatcher_co); aio_co_wake(qmp_dispatcher_co);
} }
} }