From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tao Ma Subject: Re: [PATCH] block: fix blk_queue_end_tag() Date: Wed, 21 Dec 2011 14:33:40 +0800 Message-ID: <4EF17DC4.5010008@tao.ma> References: <20111220233117.17757.71139.stgit@localhost6.localdomain6> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from oproxy1-pub.bluehost.com ([66.147.249.253]:37158 "HELO oproxy1-pub.bluehost.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751214Ab1LUGdo (ORCPT ); Wed, 21 Dec 2011 01:33:44 -0500 In-Reply-To: <20111220233117.17757.71139.stgit@localhost6.localdomain6> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Dan Williams Cc: axboe@kernel.dk, Tao Ma , Meelis Roos , linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, Ed Nadolski On 12/21/2011 07:33 AM, Dan Williams wrote: > Commit 5e081591 "block: warn if tag is greater than real_max_depth" > cleaned up blk_queue_end_tag() to warn when the tag is truly invalid > (greater than real_max_depth). However, it changed behavior in the tag > < max_depth case to not end the request. Leading to triggering of > BUG_ON(blk_queued_rq(rq)) in the request completion path: > > http://marc.info/?l=linux-kernel&m=132204370518629&w=2 > > In order to allow blk_queue_resize_tags() to shrink the tag space > blk_queue_end_tag() must always complete tags with a value less than > real_max_depth regardless of the current max_depth. > > Cc: Tao Ma > Reported-by: Meelis Roos > Reported-by: Ed Nadolski > Signed-off-by: Dan Williams > --- > Functionally the same as Tao Ma's fix [1], but just moves the warn into the > if() directly. > > [1]: http://marc.info/?l=linux-scsi&m=132439698602441&w=2 > > -- > Dan > > block/blk-tag.c | 5 +++-- > 1 files changed, 3 insertions(+), 2 deletions(-) > > diff --git a/block/blk-tag.c b/block/blk-tag.c > index e74d6d1..6e61262 100644 > --- a/block/blk-tag.c > +++ b/block/blk-tag.c > @@ -286,12 +286,13 @@ void blk_queue_end_tag(struct request_queue *q, struct request *rq) > > BUG_ON(tag == -1); > > - if (unlikely(tag >= bqt->max_depth)) { > + if (WARN_ONCE(tag >= bqt->real_max_depth, > + "%s: tag %d greater than tag map size: %d\n", > + __func__, tag, bqt->real_max_depth)) { > /* > * This can happen after tag depth has been reduced. Please also change the comments here since it should never happen in the right workload. Thanks Tao > * But tag shouldn't be larger than real_max_depth. > */ > - WARN_ON(tag >= bqt->real_max_depth); > return; > } > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/