From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161307AbcFHEta (ORCPT ); Wed, 8 Jun 2016 00:49:30 -0400 Received: from mail-pa0-f46.google.com ([209.85.220.46]:35034 "EHLO mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161006AbcFHEt2 (ORCPT ); Wed, 8 Jun 2016 00:49:28 -0400 Subject: Re: [PATCH 1/8] blk-mq: add blk_mq_alloc_request_hctx To: Christoph Hellwig , keith.busch@intel.com References: <1465248119-17875-1-git-send-email-hch@lst.de> <1465248119-17875-2-git-send-email-hch@lst.de> Cc: linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, Ming Lin From: Jens Axboe Message-ID: <5757A3D2.1030003@kernel.dk> Date: Tue, 7 Jun 2016 22:49:22 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.8.0 MIME-Version: 1.0 In-Reply-To: <1465248119-17875-2-git-send-email-hch@lst.de> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/06/2016 03:21 PM, Christoph Hellwig wrote: > From: Ming Lin > > For some protocols like NVMe over Fabrics we need to be able to send > initialization commands to a specific queue. > > Based on an earlier patch from Christoph Hellwig . > > Signed-off-by: Ming Lin > Signed-off-by: Christoph Hellwig > --- > block/blk-mq.c | 33 +++++++++++++++++++++++++++++++++ > include/linux/blk-mq.h | 2 ++ > 2 files changed, 35 insertions(+) > > diff --git a/block/blk-mq.c b/block/blk-mq.c > index 29cbc1b..7bb45ed 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -266,6 +266,39 @@ struct request *blk_mq_alloc_request(struct request_queue *q, int rw, > } > EXPORT_SYMBOL(blk_mq_alloc_request); > > +struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int rw, > + unsigned int flags, unsigned int hctx_idx) > +{ > + struct blk_mq_hw_ctx *hctx; > + struct blk_mq_ctx *ctx; > + struct request *rq; > + struct blk_mq_alloc_data alloc_data; > + int ret; > + > + ret = blk_queue_enter(q, flags & BLK_MQ_REQ_NOWAIT); > + if (ret) > + return ERR_PTR(ret); > + > + hctx = q->queue_hw_ctx[hctx_idx]; > + ctx = __blk_mq_get_ctx(q, cpumask_first(hctx->cpumask)); > + > + blk_mq_set_alloc_data(&alloc_data, q, flags, ctx, hctx); > + > + rq = __blk_mq_alloc_request(&alloc_data, rw); > + if (!rq && !(flags & BLK_MQ_REQ_NOWAIT)) { > + __blk_mq_run_hw_queue(hctx); > + > + rq = __blk_mq_alloc_request(&alloc_data, rw); > + } Why are we duplicating this code here? If NOWAIT isn't set, then we'll always return a request. bt_get() will run the queue for us, if it needs to. blk_mq_alloc_request() does this too, and I'm guessing that code was just copied. I'll fix that up. Looks like this should just be: rq = __blk_mq_alloc_request(&alloc_data, rw); if (rq) return rq; blk_queue_exit(q); return ERR_PTR(-EWOULDBLOCK); for this case. -- Jens Axboe