Il 01/06/2014 21:02, Marcin Gibuła ha scritto:
Good catch! The main problem with the patch is that you need to use
atomic_inc/atomic_dec to increment and decrement
pool->pending_completions.
Ok.
Secondarily, event_notifier_set is pretty heavy-weight, does it work if
you wrap the loop like this?
restart:
QLIST_FOREACH_SAFE(elem, &pool->head, all, next) {
...
}
if (pool->pending_completions) {
goto restart;
}
event_notifier_test_and_clear(notifier);
if (pool->pending_completions) {
event_notifier_set(notifier);
goto restart;
}
I'll test it tomorrow. I assume you want to avoid calling
event_notifier_set() until function is reentered via aio_pool?
Yes. But actually, I need to check if it's possible to fix
bdrv_drain_all. If you're in coroutine context, you can defer the
draining to a safe point using a bottom half. If you're not in
coroutine context, perhaps bdrv_drain_all has to be made illegal. Which
means a bunch of code auditing...
Paolo
Finally, the same bug is also in block/linux-aio.c and
block/win32-aio.c.
I can try with linux-aio, but my knowledge of windows api is zero...
