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[Qemu-devel] [PATCH v2 1/9] blockdev: hold AioContext for bdrv_unref() i
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PATCH v2 1/9] blockdev: hold AioContext for bdrv_unref() in external_snapshot_clean() |
Date: |
Wed, 6 Dec 2017 14:45:42 +0000 |
bdrv_unref() requires the AioContext lock because bdrv_flush() uses
BDRV_POLL_WHILE(), which assumes the AioContext is currently held. If
BDRV_POLL_WHILE() runs without AioContext held the
pthread_mutex_unlock() call in aio_context_release() fails.
This patch moves bdrv_unref() into the AioContext locked region to solve
the following pthread_mutex_unlock() failure:
#0 0x00007f566181969b in raise () at /lib64/libc.so.6
#1 0x00007f566181b3b1 in abort () at /lib64/libc.so.6
#2 0x00005592cd590458 in error_exit (err=<optimized out>, address@hidden
<__func__.23977> "qemu_mutex_unlock") at util/qemu-thread-posix.c:36
#3 0x00005592cd96e738 in qemu_mutex_unlock (address@hidden) at
util/qemu-thread-posix.c:96
#4 0x00005592cd969b69 in aio_context_release (address@hidden) at
util/async.c:507
#5 0x00005592cd8ead78 in bdrv_flush (address@hidden) at block/io.c:2478
#6 0x00005592cd89df30 in bdrv_close (bs=0x5592cfa87210) at block.c:3207
#7 0x00005592cd89df30 in bdrv_delete (bs=0x5592cfa87210) at block.c:3395
#8 0x00005592cd89df30 in bdrv_unref (bs=0x5592cfa87210) at block.c:4418
#9 0x00005592cd6b7f86 in qmp_transaction (dev_list=<optimized out>,
has_props=<optimized out>, props=<optimized out>, address@hidden) at
blockdev.c:2308
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
blockdev.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/blockdev.c b/blockdev.c
index 56a6b24a0b..3c8d994ced 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1812,8 +1812,8 @@ static void external_snapshot_clean(BlkActionState
*common)
DO_UPCAST(ExternalSnapshotState, common, common);
if (state->aio_context) {
bdrv_drained_end(state->old_bs);
- aio_context_release(state->aio_context);
bdrv_unref(state->new_bs);
+ aio_context_release(state->aio_context);
}
}
--
2.14.3
- [Qemu-devel] [PATCH v2 0/9] blockdev: fix QMP 'transaction' with IOThreads, Stefan Hajnoczi, 2017/12/06
- [Qemu-devel] [PATCH v2 1/9] blockdev: hold AioContext for bdrv_unref() in external_snapshot_clean(),
Stefan Hajnoczi <=
- [Qemu-devel] [PATCH v2 2/9] block: don't keep AioContext acquired after external_snapshot_prepare(), Stefan Hajnoczi, 2017/12/06
- [Qemu-devel] [PATCH v2 3/9] block: don't keep AioContext acquired after drive_backup_prepare(), Stefan Hajnoczi, 2017/12/06
- [Qemu-devel] [PATCH v2 4/9] block: don't keep AioContext acquired after blockdev_backup_prepare(), Stefan Hajnoczi, 2017/12/06
- [Qemu-devel] [PATCH v2 5/9] block: don't keep AioContext acquired after internal_snapshot_prepare(), Stefan Hajnoczi, 2017/12/06
- [Qemu-devel] [PATCH v2 6/9] block: drop unused BlockDirtyBitmapState->aio_context field, Stefan Hajnoczi, 2017/12/06