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authorPaolo Bonzini <pbonzini@redhat.com>2016-10-27 12:49:05 +0200
committerFam Zheng <famz@redhat.com>2016-10-28 21:50:18 +0800
commitc9d1a56174339b0afdef63b7d151b38f4bb6dae5 (patch)
tree1eb8359be422f1abbf98c5781cee063163861f67 /block/io.c
parent9e944cb4744b527dd93aa989023739375a8880fb (diff)
block: only call aio_poll on the current thread's AioContext
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>
Diffstat (limited to 'block/io.c')
-rw-r--r--block/io.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/block/io.c b/block/io.c
index 6fc0145864..be0d862ca6 100644
--- a/block/io.c
+++ b/block/io.c
@@ -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)