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Date:   Fri, 15 Mar 2019 09:30:18 -0400
From:   Josef Bacik <josef@toxicpanda.com>
To:     Christoph Hellwig <hch@lst.de>
Cc:     Jianchao Wang <jianchao.w.wang@oracle.com>, axboe@kernel.dk,
        jthumshirn@suse.de, hare@suse.de, josef@toxicpanda.com,
        bvanassche@acm.org, sagi@grimberg.me, keith.busch@intel.com,
        jsmart2021@gmail.com, linux-block@vger.kernel.org,
        linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/8]: blk-mq: use static_rqs to iterate busy tags
Message-ID: <20190315133017.lnr5cvtapo5nxilu@MacBook-Pro-91.local>
References: <1552640264-26101-1-git-send-email-jianchao.w.wang@oracle.com>
 <20190315092020.GA2405@lst.de>
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On Fri, Mar 15, 2019 at 10:20:20AM +0100, Christoph Hellwig wrote:
> On Fri, Mar 15, 2019 at 04:57:36PM +0800, Jianchao Wang wrote:
> > Hi Jens
> > 
> > As we know, there is a risk of accesing stale requests when iterate
> > in-flight requests with tags->rqs[] and this has been talked in following
> > thread,
> > [1] https://marc.info/?l=linux-scsi&m=154511693912752&w=2
> > [2] https://marc.info/?l=linux-block&m=154526189023236&w=2
> 
> I'd rather take one step back and figure out why we are iterating
> the busy requests.  There really shouldn't be any reason why a driver
> is even doings that (vs some error handling helpers in the core
> block code that can properly synchronize).

I use it in NBD to error out any pending requests for forced disconnects.  I'd
be happy to use some other blessed interface, I'm not married to this one.
Thanks,

Josef