diff options
author | Paolo Bonzini <pbonzini@redhat.com> | 2017-12-07 20:13:15 +0000 |
---|---|---|
committer | Stefan Hajnoczi <stefanha@redhat.com> | 2017-12-19 10:25:09 +0000 |
commit | bd6458e410c1e7d2912357aeb399fe7d8ee9f9a3 (patch) | |
tree | 67e60c6baf30b7a210719b7c92d50b15ce5079bb /block.c | |
parent | 0a75b60cdb685fed09ac0c0783bc0d6052a00e5d (diff) | |
download | qemu-bd6458e410c1e7d2912357aeb399fe7d8ee9f9a3.zip qemu-bd6458e410c1e7d2912357aeb399fe7d8ee9f9a3.tar.gz qemu-bd6458e410c1e7d2912357aeb399fe7d8ee9f9a3.tar.bz2 |
block: avoid recursive AioContext acquire in bdrv_inactivate_all()
BDRV_POLL_WHILE() does not support recursive AioContext locking. It
only releases the AioContext lock once regardless of how many times the
caller has acquired it. This results in a hang since the IOThread does
not make progress while the AioContext is still locked.
The following steps trigger the hang:
$ qemu-system-x86_64 -M accel=kvm -m 1G -cpu host \
-object iothread,id=iothread0 \
-device virtio-scsi-pci,iothread=iothread0 \
-drive if=none,id=drive0,file=test.img,format=raw \
-device scsi-hd,drive=drive0 \
-drive if=none,id=drive1,file=test.img,format=raw \
-device scsi-hd,drive=drive1
$ qemu-system-x86_64 ...same options... \
-incoming tcp::1234
(qemu) migrate tcp:127.0.0.1:1234
...hang...
Tested-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20171207201320.19284-2-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'block.c')
-rw-r--r-- | block.c | 14 |
1 files changed, 11 insertions, 3 deletions
@@ -4320,9 +4320,15 @@ int bdrv_inactivate_all(void) BdrvNextIterator it; int ret = 0; int pass; + GSList *aio_ctxs = NULL, *ctx; for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { - aio_context_acquire(bdrv_get_aio_context(bs)); + AioContext *aio_context = bdrv_get_aio_context(bs); + + if (!g_slist_find(aio_ctxs, aio_context)) { + aio_ctxs = g_slist_prepend(aio_ctxs, aio_context); + aio_context_acquire(aio_context); + } } /* We do two passes of inactivation. The first pass calls to drivers' @@ -4340,9 +4346,11 @@ int bdrv_inactivate_all(void) } out: - for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { - aio_context_release(bdrv_get_aio_context(bs)); + for (ctx = aio_ctxs; ctx != NULL; ctx = ctx->next) { + AioContext *aio_context = ctx->data; + aio_context_release(aio_context); } + g_slist_free(aio_ctxs); return ret; } |