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| author | Paolo Bonzini <pbonzini@redhat.com> | 2016-10-27 12:49:05 +0200 |
|---|---|---|
| committer | Fam Zheng <famz@redhat.com> | 2016-10-28 21:50:18 +0800 |
| commit | c9d1a56174339b0afdef63b7d151b38f4bb6dae5 (patch) | |
| tree | 1eb8359be422f1abbf98c5781cee063163861f67 /block.c | |
| parent | 9e944cb4744b527dd93aa989023739375a8880fb (diff) | |
| download | focaccia-qemu-c9d1a56174339b0afdef63b7d151b38f4bb6dae5.tar.gz focaccia-qemu-c9d1a56174339b0afdef63b7d151b38f4bb6dae5.zip | |
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.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/block.c b/block.c index fbe485c4f8..a17baab1d0 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)) { |