Re: [PATCH 3.2-rc5] block: don't kick empty queue inblk_drain_queue()

From: Wu Fengguang
Date: Thu Dec 15 2011 - 21:29:59 EST


Thanks! It fixed the problem for me.

On Fri, Dec 16, 2011 at 02:58:42AM +0800, Tejun Heo wrote:
> 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:
> [<ffffffff81039a6a>] warn_slowpath_common+0x7a/0xb0
> [<ffffffff81039b41>] warn_slowpath_fmt+0x41/0x50
> [<ffffffff813d657f>] do_fd_request+0xbf/0xd0
> [<ffffffff81322b95>] blk_drain_queue+0x65/0x80
> [<ffffffff81322c93>] blk_cleanup_queue+0xe3/0x1a0
> [<ffffffff818a809d>] floppy_init+0xdeb/0xe28
> [<ffffffff818a72b2>] ? daring+0x6b/0x6b
> [<ffffffff810002af>] do_one_initcall+0x3f/0x170
> [<ffffffff81884b34>] kernel_init+0x9d/0x11e
> [<ffffffff810317c2>] ? schedule_tail+0x22/0xa0
> [<ffffffff815dbb14>] kernel_thread_helper+0x4/0x10
> [<ffffffff81884a97>] ? start_kernel+0x2be/0x2be
> [<ffffffff815dbb10>] ? 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 <tj@xxxxxxxxxx>
> Reported-by: Ralf Hildebrandt <Ralf.Hildebrandt@xxxxxxxxxx>
> Reported-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
> Tested-by: Sergei Trofimovich <slyich@xxxxxxxxx>
> ---
> 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];
--
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