From: Asias He Date: Fri, 4 May 2012 12:22:04 +0000 (+0800) Subject: virtio-blk: Fix hot-unplug race in remove method X-Git-Tag: v3.2.29~10 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e5000b33460e5008a3a189dc2107d274d8096eff;p=pandora-kernel.git virtio-blk: Fix hot-unplug race in remove method commit b79d866c8b7014a51f611a64c40546109beaf24a upstream. If we reset the virtio-blk device before the requests already dispatched to the virtio-blk driver from the block layer are finised, we will stuck in blk_cleanup_queue() and the remove will fail. blk_cleanup_queue() calls blk_drain_queue() to drain all requests queued before DEAD marking. However it will never success if the device is already stopped. We'll have q->in_flight[] > 0, so the drain will not finish. How to reproduce the race: 1. hot-plug a virtio-blk device 2. keep reading/writing the device in guest 3. hot-unplug while the device is busy serving I/O Test: ~1000 rounds of hot-plug/hot-unplug test passed with this patch. Changes in v3: - Drop blk_abort_queue and blk_abort_request - Use __blk_end_request_all to complete request dispatched to driver Changes in v2: - Drop req_in_flight - Use virtqueue_detach_unused_buf to get request dispatched to driver Signed-off-by: Asias He Signed-off-by: Rusty Russell Signed-off-by: Ben Hutchings --- Reading git-diff-tree failed