diff options
| 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 | |
| parent | 9e944cb4744b527dd93aa989023739375a8880fb (diff) | |
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')
| -rw-r--r-- | block/io.c | 12 | ||||
| -rw-r--r-- | block/nfs.c | 1 | ||||
| -rw-r--r-- | block/sheepdog.c | 3 |
3 files changed, 16 insertions, 0 deletions
diff --git a/block/io.c b/block/io.c index 6fc0145864..be0d862ca6 100644 --- a/block/io.c +++ b/block/io.c @@ -474,9 +474,21 @@ void bdrv_inc_in_flight(BlockDriverState *bs) atomic_inc(&bs->in_flight); } +static void dummy_bh_cb(void *opaque) +{ +} + +void bdrv_wakeup(BlockDriverState *bs) +{ + if (bs->wakeup) { + aio_bh_schedule_oneshot(qemu_get_aio_context(), dummy_bh_cb, NULL); + } +} + void bdrv_dec_in_flight(BlockDriverState *bs) { atomic_dec(&bs->in_flight); + bdrv_wakeup(bs); } static bool coroutine_fn wait_serialising_requests(BdrvTrackedRequest *self) diff --git a/block/nfs.c b/block/nfs.c index 7474fbc7cc..88c60a9118 100644 --- a/block/nfs.c +++ b/block/nfs.c @@ -505,6 +505,7 @@ nfs_get_allocated_file_size_cb(int ret, struct nfs_context *nfs, void *data, error_report("NFS Error: %s", nfs_get_error(nfs)); } task->complete = 1; + bdrv_wakeup(task->bs); } static int64_t nfs_get_allocated_file_size(BlockDriverState *bs) diff --git a/block/sheepdog.c b/block/sheepdog.c index 16a5c1c28d..1fb917343a 100644 --- a/block/sheepdog.c +++ b/block/sheepdog.c @@ -702,6 +702,9 @@ out: srco->ret = ret; srco->finished = true; + if (srco->bs) { + bdrv_wakeup(srco->bs); + } } /* |