From: Anthony PERARD <[email protected]>
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/[email protected]/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 <[email protected]>
---
There's maybe an issue in thread_pool_submit_aio() as well with
signalling `request_cond`, but maybe it's much less likely to be an
issue?
---
util/thread-pool.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/util/thread-pool.c b/util/thread-pool.c
index 0d97888df0..e3d8292d14 100644
--- a/util/thread-pool.c
+++ b/util/thread-pool.c
@@ -120,13 +120,13 @@ static void *worker_thread(void *opaque)
pool->cur_threads--;
qemu_cond_signal(&pool->worker_stopped);
- qemu_mutex_unlock(&pool->lock);
/*
* Wake up another thread, in case we got a wakeup but decided
* to exit due to pool->cur_threads > pool->max_threads.
*/
qemu_cond_signal(&pool->request_cond);
+ qemu_mutex_unlock(&pool->lock);
return NULL;
}
--
Anthony PERARD
