From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759318Ab1LOS6u (ORCPT ); Thu, 15 Dec 2011 13:58:50 -0500 Received: from mail-fx0-f46.google.com ([209.85.161.46]:63400 "EHLO mail-fx0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756321Ab1LOS6t (ORCPT ); Thu, 15 Dec 2011 13:58:49 -0500 Date: Thu, 15 Dec 2011 10:58:42 -0800 From: Tejun Heo To: Jens Axboe Cc: linux-kernel@vger.kernel.org, Tim Gardner , Sergei Trofimovich , Ralf Hildebrandt , Wu Fengguang Subject: [PATCH 3.2-rc5] block: don't kick empty queue in blk_drain_queue() Message-ID: <20111215185842.GB32002@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org While probing, fd sets up queue, probes hardware and tears down the queue if probing fails. In the process, blk_drain_queue() kicks the queue which failed to finish initialization and fd is unhappy about that. floppy0: no floppy controllers found ------------[ cut here ]------------ WARNING: at drivers/block/floppy.c:2929 do_fd_request+0xbf/0xd0() Hardware name: To Be Filled By O.E.M. VFS: do_fd_request called on non-open device Modules linked in: Pid: 1, comm: swapper Not tainted 3.2.0-rc4-00077-g5983fe2 #2 Call Trace: [] warn_slowpath_common+0x7a/0xb0 [] warn_slowpath_fmt+0x41/0x50 [] do_fd_request+0xbf/0xd0 [] blk_drain_queue+0x65/0x80 [] blk_cleanup_queue+0xe3/0x1a0 [] floppy_init+0xdeb/0xe28 [] ? daring+0x6b/0x6b [] do_one_initcall+0x3f/0x170 [] kernel_init+0x9d/0x11e [] ? schedule_tail+0x22/0xa0 [] kernel_thread_helper+0x4/0x10 [] ? start_kernel+0x2be/0x2be [] ? gs_change+0xb/0xb Avoid it by making blk_drain_queue() kick queue iff dispatch queue has something on it. Signed-off-by: Tejun Heo Reported-by: Ralf Hildebrandt Reported-by: Wu Fengguang Tested-by: Sergei Trofimovich --- block/blk-core.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/block/blk-core.c b/block/blk-core.c index ea70e6c..e9aa3d5 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -366,7 +366,14 @@ void blk_drain_queue(struct request_queue *q, bool drain_all) if (drain_all) blk_throtl_drain(q); - __blk_run_queue(q); + /* + * This function might be called on a queue which failed + * driver init after queue creation. Some drivers + * (e.g. fd) get unhappy in such cases. Kick queue iff + * dispatch queue has something on it. + */ + if (!list_empty(&q->queue_head)) + __blk_run_queue(q); if (drain_all) nr_rqs = q->rq.count[0] + q->rq.count[1];