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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.c
parent9e944cb4744b527dd93aa989023739375a8880fb (diff)
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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.c')
-rw-r--r--block.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/block.c b/block.c
index fbe485c..a17baab 100644
--- a/block.c
+++ b/block.c
@@ -2090,7 +2090,9 @@ int bdrv_reopen_multiple(AioContext *ctx, BlockReopenQueue *bs_queue, Error **er
assert(bs_queue != NULL);
+ aio_context_release(ctx);
bdrv_drain_all();
+ aio_context_acquire(ctx);
QSIMPLEQ_FOREACH(bs_entry, bs_queue, entry) {
if (bdrv_reopen_prepare(&bs_entry->state, bs_queue, &local_err)) {