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Subject: Re: [PATCH V4 0/2] fixes for the updating nr_hw_queues
To:     Jianchao Wang <jianchao.w.wang@oracle.com>
Cc:     tom.leiming@gmail.com, bart.vanassche@wdc.com,
        keith.busch@linux.intel.com, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org
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From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <94238d71-9f39-1378-5f86-9093d0d2cf32@kernel.dk>
Date:   Tue, 21 Aug 2018 09:02:33 -0600
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On 8/21/18 1:15 AM, Jianchao Wang wrote:
> Hi Jens
> 
> Two fixes for updating nr_hw_queues.
> 
> The first patch fixes the following scenario:
> io scheduler (kyber) depends on the mapping between ctx and hctx.
> When update nr_hw_queues, io scheduler's init_hctx will be
> invoked before the mapping is adapted correctly, this would cause
> panic in kyber.
> 
> The second patch fixes the following scenario:
> part_in_flight/rw will invoke blk_mq_in_flight/rw to account the
> inflight requests. It will access the queue_hw_ctx and nr_hw_queues
> w/o any protection. When updating nr_hw_queues and blk_mq_in_flight
> /rw occur concurrently, panic comes up.

This looks good to me know, I'll queue it up for some testing.

-- 
Jens Axboe