thread_pool_free() might have been called on the `pool`, which would
be a reason for worker_thread() to quit. In this case,
`pool->request_cond` is been destroyed.
If worker_thread() didn't managed to signal `request_cond` before it
been destroyed by thread_pool_free(), we got:
util/qemu-thread-posix.c:198: qemu_cond_signal: Assertion `cond->initialized' failed.
One backtrace:
__GI___assert_fail (assertion=0x55555614abcb "cond->initialized", file=0x55555614ab88 "util/qemu-thread-posix.c", line=198,
function=0x55555614ad80 <__PRETTY_FUNCTION__.17104> "qemu_cond_signal") at assert.c:101
qemu_cond_signal (cond=0x7fffb800db30) at util/qemu-thread-posix.c:198
worker_thread (opaque=0x7fffb800dab0) at util/thread-pool.c:129
qemu_thread_start (args=0x7fffb8000b20) at util/qemu-thread-posix.c:505
start_thread (arg=<optimized out>) at pthread_create.c:486
Reported here:
https://lore.kernel.org/all/ZJwoK50FcnTSfFZ8@MacBook-Air-de-Roger.local/T/#u
To avoid issue, keep lock while sending a signal to `request_cond`.
Fixes: 900fa208f506 ("thread-pool: replace semaphore with condition variable")
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20230714152720.5077-1-anthony.perard@citrix.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
(cherry picked from commit f4f71363fcdb1092ff64d2bba6f9af39570c2f2b)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
e4aae3f819