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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 /async.c
parent9e944cb4744b527dd93aa989023739375a8880fb (diff)
downloadqemu-arm-c9d1a56174339b0afdef63b7d151b38f4bb6dae5.tar.gz
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 'async.c')
-rw-r--r--async.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/async.c b/async.c
index f30d011ebc..fb37b031cb 100644
--- a/async.c
+++ b/async.c
@@ -61,6 +61,7 @@ void aio_bh_schedule_oneshot(AioContext *ctx, QEMUBHFunc *cb, void *opaque)
smp_wmb();
ctx->first_bh = bh;
qemu_mutex_unlock(&ctx->bh_lock);
+ aio_notify(ctx);
}
QEMUBH *aio_bh_new(AioContext *ctx, QEMUBHFunc *cb, void *opaque)