motorhead/qemu
1
0
Fork 0
mirror of https://github.com/Motorhead1991/qemu.git synced 2025-08-04 00:03:54 -06:00
Code Issues Projects Releases Packages Wiki Activity Actions

block: only call aio_poll on the current thread's AioContext

Browse source 
aio_poll is not thread safe; for example bdrv_drain can hang if
the last in-flight I/O operation is completed in the I/O thread after
the main thread has checked bs->in_flight.

The bug remains latent as long as all of it is called within
aio_context_acquire/aio_context_release, but this will change soon.

To fix this, if bdrv_drain is called from outside the I/O thread,
signal the main AioContext through a dummy bottom half.  The event
loop then only runs in the I/O thread.

Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1477565348-5458-18-git-send-email-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
This commit is contained in:
Paolo Bonzini 2016-10-27 12:49:05 +02:00 • committed by Fam Zheng
parent 9e944cb474
commit c9d1a56174
8 changed files with 60 additions and 6 deletions
Download patch file Download diff file Expand all files Collapse all files

12
block/io.c
View file

@ -474,9 +474,21 @@ void bdrv_inc_in_flight(BlockDriverState *bs)
atomic_inc(&bs->in_flight);
}
static void dummy_bh_cb(void *opaque)
{
}
void bdrv_wakeup(BlockDriverState *bs)
{
if (bs->wakeup) {
aio_bh_schedule_oneshot(qemu_get_aio_context(), dummy_bh_cb, NULL);
}
}
void bdrv_dec_in_flight(BlockDriverState *bs)
{
atomic_dec(&bs->in_flight);
bdrv_wakeup(bs);
}
static bool coroutine_fn wait_serialising_requests(BdrvTrackedRequest *self)