From mboxrd@z Thu Jan  1 00:00:00 1970
From: Bart Van Assche <bvanassche@acm.org>
Subject: Re: [PATCH V3 3/6] blk-mq: free hw queue's resource in hctx's
 release handler
Date: Wed, 03 Apr 2019 09:26:32 -0700
Message-ID: <1554308792.118779.221.camel@acm.org>
References: <20190403102609.18707-1-ming.lei@redhat.com>
         <20190403102609.18707-4-ming.lei@redhat.com>
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In-Reply-To: <20190403102609.18707-4-ming.lei@redhat.com>
Sender: stable-owner@vger.kernel.org
To: Ming Lei <ming.lei@redhat.com>, Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org, Dongli Zhang <dongli.zhang@oracle.com>, James Smart <james.smart@broadcom.com>, Bart Van Assche <bart.vanassche@wdc.com>, linux-scsi@vger.kernel.org, "Martin K . Petersen" <martin.petersen@oracle.com>, Christoph Hellwig <hch@lst.de>, "James E . J . Bottomley" <jejb@linux.vnet.ibm.com>, jianchao wang <jianchao.w.wang@oracle.com>, stable@vger.kernel.org
List-Id: linux-scsi@vger.kernel.org

On Wed, 2019-04-03 at 18:26 +-0800, Ming Lei wrote:
+AD4 diff --git a/block/blk-core.c b/block/blk-core.c
+AD4 index 6583d67f3e34..20298aa5a77c 100644
+AD4 --- a/block/blk-core.c
+AD4 +-+-+- b/block/blk-core.c
+AD4 +AEAAQA -374,7 +-374,7 +AEAAQA void blk+AF8-cleanup+AF8-queue(struct request+AF8-queue +ACo-q)
+AD4         blk+AF8-exit+AF8-queue(q)+ADs
+AD4  
+AD4         if (queue+AF8-is+AF8-mq(q))
+AD4 -               blk+AF8-mq+AF8-free+AF8-queue(q)+ADs
+AD4 +-               blk+AF8-mq+AF8-exit+AF8-queue(q)+ADs
+AD4  
+AD4         percpu+AF8-ref+AF8-exit(+ACY-q-+AD4-q+AF8-usage+AF8-counter)+ADs
+AD4  
+AD4 diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c
+AD4 index 3f9c3f4ac44c..4040e62c3737 100644
+AD4 --- a/block/blk-mq-sysfs.c
+AD4 +-+-+- b/block/blk-mq-sysfs.c
+AD4 +AEAAQA -10,6 +-10,7 +AEAAQA
+AD4  +ACM-include +ADw-linux/smp.h+AD4
+AD4  
+AD4  +ACM-include +ADw-linux/blk-mq.h+AD4
+AD4 +-+ACM-include +ACI-blk.h+ACI
+AD4  +ACM-include +ACI-blk-mq.h+ACI
+AD4  +ACM-include +ACI-blk-mq-tag.h+ACI
+AD4  
+AD4 +AEAAQA -33,6 +-34,11 +AEAAQA static void blk+AF8-mq+AF8-hw+AF8-sysfs+AF8-release(struct kobject +ACo-kobj)
+AD4  +AHs
+AD4         struct blk+AF8-mq+AF8-hw+AF8-ctx +ACo-hctx +AD0 container+AF8-of(kobj, struct blk+AF8-mq+AF8-hw+AF8-ctx,
+AD4                                                   kobj)+ADs
+AD4 +-
+AD4 +-       if (hctx-+AD4-flags +ACY BLK+AF8-MQ+AF8-F+AF8-BLOCKING)
+AD4 +-               cleanup+AF8-srcu+AF8-struct(hctx-+AD4-srcu)+ADs
+AD4 +-       blk+AF8-free+AF8-flush+AF8-queue(hctx-+AD4-fq)+ADs
+AD4 +-       sbitmap+AF8-free(+ACY-hctx-+AD4-ctx+AF8-map)+ADs
+AD4         free+AF8-cpumask+AF8-var(hctx-+AD4-cpumask)+ADs
+AD4         kfree(hctx-+AD4-ctxs)+ADs
+AD4         kfree(hctx)+ADs
+AD4 diff --git a/block/blk-mq.c b/block/blk-mq.c
+AD4 index b512ba0cb359..afc9912e2e42 100644
+AD4 --- a/block/blk-mq.c
+AD4 +-+-+- b/block/blk-mq.c
+AD4 +AEAAQA -2259,12 +-2259,7 +AEAAQA static void blk+AF8-mq+AF8-exit+AF8-hctx(struct request+AF8-queue +ACo-q,
+AD4         if (set-+AD4-ops-+AD4-exit+AF8-hctx)
+AD4                 set-+AD4-ops-+AD4-exit+AF8-hctx(hctx, hctx+AF8-idx)+ADs
+AD4  
+AD4 -       if (hctx-+AD4-flags +ACY BLK+AF8-MQ+AF8-F+AF8-BLOCKING)
+AD4 -               cleanup+AF8-srcu+AF8-struct(hctx-+AD4-srcu)+ADs
+AD4 -
+AD4         blk+AF8-mq+AF8-remove+AF8-cpuhp(hctx)+ADs
+AD4 -       blk+AF8-free+AF8-flush+AF8-queue(hctx-+AD4-fq)+ADs
+AD4 -       sbitmap+AF8-free(+ACY-hctx-+AD4-ctx+AF8-map)+ADs
+AD4  +AH0
+AD4  
+AD4  static void blk+AF8-mq+AF8-exit+AF8-hw+AF8-queues(struct request+AF8-queue +ACo-q,
+AD4 +AEAAQA -2899,7 +-2894,8 +AEAAQA struct request+AF8-queue +ACo-blk+AF8-mq+AF8-init+AF8-allocated+AF8-queue(struct blk+AF8-mq+AF8-tag+AF8-set +ACo-set,
+AD4  +AH0
+AD4  EXPORT+AF8-SYMBOL(blk+AF8-mq+AF8-init+AF8-allocated+AF8-queue)+ADs
+AD4  
+AD4 -void blk+AF8-mq+AF8-free+AF8-queue(struct request+AF8-queue +ACo-q)
+AD4 +-/+ACo tags can +AF8-not+AF8 be used after returning from blk+AF8-mq+AF8-exit+AF8-queue +ACo-/
+AD4 +-void blk+AF8-mq+AF8-exit+AF8-queue(struct request+AF8-queue +ACo-q)
+AD4  +AHs
+AD4         struct blk+AF8-mq+AF8-tag+AF8-set   +ACo-set +AD0 q-+AD4-tag+AF8-set+ADs
+AD4  
+AD4 diff --git a/block/blk-mq.h b/block/blk-mq.h
+AD4 index d704fc7766f4..c421e3a16e36 100644
+AD4 --- a/block/blk-mq.h
+AD4 +-+-+- b/block/blk-mq.h
+AD4 +AEAAQA -37,7 +-37,7 +AEAAQA struct blk+AF8-mq+AF8-ctx +AHs
+AD4         struct kobject          kobj+ADs
+AD4  +AH0 +AF8AXwBfAF8-cacheline+AF8-aligned+AF8-in+AF8-smp+ADs
+AD4  
+AD4 -void blk+AF8-mq+AF8-free+AF8-queue(struct request+AF8-queue +ACo-q)+ADs
+AD4 +-void blk+AF8-mq+AF8-exit+AF8-queue(struct request+AF8-queue +ACo-q)+ADs
+AD4  int blk+AF8-mq+AF8-update+AF8-nr+AF8-requests(struct request+AF8-queue +ACo-q, unsigned int nr)+ADs
+AD4  void blk+AF8-mq+AF8-wake+AF8-waiters(struct request+AF8-queue +ACo-q)+ADs
+AD4  bool blk+AF8-mq+AF8-dispatch+AF8-rq+AF8-list(struct request+AF8-queue +ACo, struct list+AF8-head +ACo, bool)+ADs

Isn't this an incomplete solution? The above patch fixes the race between
cleaning up a queue and running a queue but does not address the race between
running a queue and changing the number of hardware queues.

Thanks,

Bart.