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Subject: Re: [PATCH 6/8] skd: use blk_mq_queue_tag_busy_iter
From:   Bart Van Assche <bvanassche@acm.org>
To:     Jianchao Wang <jianchao.w.wang@oracle.com>, axboe@kernel.dk
Cc:     hch@lst.de, jthumshirn@suse.de, hare@suse.de, josef@toxicpanda.com,
        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
Date:   Mon, 18 Mar 2019 10:20:35 -0700
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On Fri, 2019-03-15 at 16:57 +-0800, Jianchao Wang wrote:
+AD4 blk+AF8-mq+AF8-tagset+AF8-busy+AF8-iter is not safe that it could get stale request
+AD4 in tags-+AD4-rqs+AFsAXQ. Use blk+AF8-mq+AF8-queue+AF8-tag+AF8-busy+AF8-iter here.
+AD4 
+AD4 Signed-off-by: Jianchao Wang +ADw-jianchao.w.wang+AEA-oracle.com+AD4
+AD4 ---
+AD4  drivers/block/skd+AF8-main.c +AHw 4 ++1filechanged2insertions(), 2 deletions(-)
+AD4 
+AD4 diff --git a/drivers/block/skd+AF8-main.c b/drivers/block/skd+AF8-main.c
+AD4 index ab893a7..60c34ff 100644
+AD4 --- a/drivers/block/skd+AF8-main.c
+AD4 diff --git a/drivers/block/skd+AF8-main.c b/drivers/block/skd+AF8-main.c
+AD4 index ab893a7..60c34ff 100644
+AD4 --- a/drivers/block/skd+AF8-main.c
+AD4 +-+-+- b/drivers/block/skd+AF8-main.c
+AD4 +AEAAQA -395,7 +-395,7 +AEAAQA static int skd+AF8-in+AF8-flight(struct skd+AF8-device +ACo-skdev)
+AD4  +AHs
+AD4         int count +AD0 0+ADs
+AD4  
+AD4 -       blk+AF8-mq+AF8-tagset+AF8-busy+AF8-iter(+ACY-skdev-+AD4-tag+AF8-set, skd+AF8-inc+AF8-in+AF8-flight, +ACY-count)+ADs
+AD4 +-       blk+AF8-mq+AF8-queue+AF8-tag+AF8-busy+AF8-iter(skdev-+AD4-queue, skd+AF8-inc+AF8-in+AF8-flight, +ACY-count, true)+ADs
+AD4  
+AD4         return count+ADs
+AD4  +AH0

Hi Jianchao,

If you have a look at the skd+AF8-in+AF8-flight() callers you will see that the above
change is not necessary.

+AD4 +AEAAQA -1916,7 +-1916,7 +AEAAQA static bool skd+AF8-recover+AF8-request(struct request +ACo-req, void +ACo-data, bool reserved)
+AD4  
+AD4  static void skd+AF8-recover+AF8-requests(struct skd+AF8-device +ACo-skdev)
+AD4  +AHs
+AD4 -	blk+AF8-mq+AF8-tagset+AF8-busy+AF8-iter(+ACY-skdev-+AD4-tag+AF8-set, skd+AF8-recover+AF8-request, skdev)+ADs
+AD4 +-	blk+AF8-mq+AF8-queue+AF8-tag+AF8-busy+AF8-iter(skdev-+AD4-queue, skd+AF8-recover+AF8-request, skdev, true)+ADs
+AD4  +AH0

Same comment here. If you have a look at the callers of this function you will
see that this change is not necessary.

Thanks,

Bart.