From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45475) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cv3ze-00062Q-1F for qemu-devel@nongnu.org; Mon, 03 Apr 2017 11:34:14 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cv3zd-0007AQ-05 for qemu-devel@nongnu.org; Mon, 03 Apr 2017 11:34:10 -0400 From: Max Reitz Date: Mon, 3 Apr 2017 17:33:41 +0200 Message-Id: <20170403153355.19722-2-mreitz@redhat.com> In-Reply-To: <20170403153355.19722-1-mreitz@redhat.com> References: <20170403153355.19722-1-mreitz@redhat.com> Subject: [Qemu-devel] [PULL 01/15] block: add missed aio_context_acquire into release_drive List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-block@nongnu.org Cc: qemu-devel@nongnu.org, Max Reitz , Peter Maydell From: "Denis V. Lunev" Recently we expirience hang with iothreads enabled with the following call trace: Thread 1 (Thread 0x7fa95efebc80 (LWP 177117)): 0 ppoll () from /lib64/libc.so.6 2 qemu_poll_ns () at qemu-timer.c:313 3 aio_poll () at aio-posix.c:457 4 bdrv_flush () at block/io.c:2641 5 bdrv_close () at block.c:2143 6 bdrv_delete () at block.c:2352 7 bdrv_unref () at block.c:3429 8 blk_remove_bs () at block/block-backend.c:427 9 blk_delete () at block/block-backend.c:178 10 blk_unref () at block/block-backend.c:226 11 object_property_del_all () at qom/object.c:399 12 object_finalize () at qom/object.c:461 13 object_unref () at qom/object.c:898 14 object_property_del_child () at qom/object.c:422 15 qmp_marshal_device_del () at qmp-marshal.c:1145 16 handle_qmp_command () at /usr/src/debug/qemu-2.6.0/monitor.c:3929 Technically bdrv_flush() stucks in while (rwco.ret == NOT_DONE) { aio_poll(aio_context, true); } but rwco.ret is equal to 0 thus we have missed wakeup. Code investigation reveals that we do not have performed aio_context_acquire() on this call stack. This patch adds missed lock. Signed-off-by: Denis V. Lunev CC: Kevin Wolf CC: Max Reitz CC: Eric Blake CC: Markus Armbruster Message-id: 1490717566-25516-1-git-send-email-den@openvz.org Reviewed-by: Fam Zheng Signed-off-by: Max Reitz --- hw/core/qdev-properties-system.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/hw/core/qdev-properties-system.c b/hw/core/qdev-properties-system.c index c34be1c1ba..e885e650fb 100644 --- a/hw/core/qdev-properties-system.c +++ b/hw/core/qdev-properties-system.c @@ -124,8 +124,12 @@ static void release_drive(Object *obj, const char *name, void *opaque) BlockBackend **ptr = qdev_get_prop_ptr(dev, prop); if (*ptr) { + AioContext *ctx = blk_get_aio_context(*ptr); + + aio_context_acquire(ctx); blockdev_auto_del(*ptr); blk_detach_dev(*ptr, dev); + aio_context_release(ctx); } } -- 2.12.1