From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1755692AbcFGP1f (ORCPT <rfc822;w@1wt.eu>);
	Tue, 7 Jun 2016 11:27:35 -0400
Received: from mail.kernel.org ([198.145.29.136]:50374 "EHLO mail.kernel.org"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1755674AbcFGP1e (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Tue, 7 Jun 2016 11:27:34 -0400
MIME-Version: 1.0
In-Reply-To: <20160607145736.GB28414@localhost.localdomain>
References: <1465248119-17875-1-git-send-email-hch@lst.de> <1465248119-17875-2-git-send-email-hch@lst.de>
 <20160607145736.GB28414@localhost.localdomain>
From: Ming Lin <mlin@kernel.org>
Date: Tue, 7 Jun 2016 08:27:29 -0700
X-Gmail-Original-Message-ID: <CAF1ivSYpbzPF+5_e+hEKZ_-t7=UhijULbkvF=SodSF7FD5YS-A@mail.gmail.com>
Message-ID: <CAF1ivSYpbzPF+5_e+hEKZ_-t7=UhijULbkvF=SodSF7FD5YS-A@mail.gmail.com>
Subject: Re: [PATCH 1/8] blk-mq: add blk_mq_alloc_request_hctx
To: Keith Busch <keith.busch@intel.com>
Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
        linux-nvme@lists.infradead.org, linux-block@vger.kernel.org,
        lkml <linux-kernel@vger.kernel.org>, Ming Lin <ming.l@ssi.samsung.com>
Content-Type: text/plain; charset=UTF-8
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Tue, Jun 7, 2016 at 7:57 AM, Keith Busch <keith.busch@intel.com> wrote:
> On Mon, Jun 06, 2016 at 11:21:52PM +0200, Christoph Hellwig wrote:
>> +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];
>
> We probably want to check 'if (hctx_idx < q->nr_hw_queues)' before
> getting the hctx. Even if hctx_idx was origially valid, it's possible
> (though unlikely) blk_queue_enter waits on reallocating h/w contexts,
> which can make hctx_idx invalid.

Yes, I'll update it.