From: Ming Lei <ming.lei@redhat.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, Hannes Reinecke <hare@suse.com>,
Keith Busch <keith.busch@intel.com>,
linux-nvme@lists.infradead.org, Sagi Grimberg <sagi@grimberg.me>,
James Smart <james.smart@broadcom.com>,
Dongli Zhang <dongli.zhang@oracle.com>,
Bart Van Assche <bart.vanassche@wdc.com>,
linux-scsi@vger.kernel.org,
"Martin K . Petersen" <martin.petersen@oracle.com>,
"James E . J . Bottomley" <jejb@linux.vnet.ibm.com>
Subject: Re: [PATCH V7 1/9] blk-mq: grab .q_usage_counter when queuing request from plug code path
Date: Thu, 25 Apr 2019 15:35:43 +0800 [thread overview]
Message-ID: <20190425073542.GA28630@ming.t460p> (raw)
In-Reply-To: <20190425053234.GA7166@lst.de>
On Thu, Apr 25, 2019 at 07:32:34AM +0200, Christoph Hellwig wrote:
> On Thu, Apr 25, 2019 at 08:53:34AM +0800, Ming Lei wrote:
> > It isn't in other callers of blk_mq_sched_insert_requests(), it is just
> > needed in some corner case like flush plug context.
> >
> > For other callers of blk_mq_sched_insert_requests(), it is guaranteed
> > that request queue's ref is held.
>
> In both Linus' tree and Jens' for-5.2 tree I only see these two
> callers of blk_mq_sched_insert_requests. What am I missing?
OK, what I meant is that the issue is flush plug context specific.
And I didn't notice that this function is only called by
blk_mq_flush_plug_list().
Then it is fine to move the percpu_ref_get()/percpu_ref_put() into
the function, better with comment on this issue.
Thanks,
Ming
next prev parent reply other threads:[~2019-04-25 7:35 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-24 11:02 [PATCH V7 0/9] blk-mq: fix races related with freeing queue Ming Lei
2019-04-24 11:02 ` [PATCH V7 1/9] blk-mq: grab .q_usage_counter when queuing request from plug code path Ming Lei
2019-04-24 16:18 ` Christoph Hellwig
2019-04-25 0:53 ` Ming Lei
2019-04-25 5:32 ` Christoph Hellwig
2019-04-25 7:35 ` Ming Lei [this message]
2019-04-24 11:02 ` [PATCH V7 2/9] blk-mq: move cancel of requeue_work into blk_mq_release Ming Lei
2019-04-24 16:18 ` Christoph Hellwig
2019-04-24 11:02 ` [PATCH V7 3/9] blk-mq: free hw queue's resource in hctx's release handler Ming Lei
2019-04-24 16:19 ` Christoph Hellwig
2019-04-24 11:02 ` [PATCH V7 4/9] blk-mq: move all hctx alloction & initialization into __blk_mq_alloc_and_init_hctx Ming Lei
2019-04-24 16:22 ` Christoph Hellwig
2019-04-25 0:55 ` Ming Lei
2019-04-26 15:09 ` Christoph Hellwig
2019-04-25 1:02 ` Ming Lei
2019-04-24 11:02 ` [PATCH V7 5/9] blk-mq: split blk_mq_alloc_and_init_hctx into two parts Ming Lei
2019-04-24 11:02 ` [PATCH V7 6/9] blk-mq: always free hctx after request queue is freed Ming Lei
2019-04-24 11:15 ` Hannes Reinecke
2019-04-24 11:02 ` [PATCH V7 7/9] blk-mq: move cancel of hctx->run_work into blk_mq_hw_sysfs_release Ming Lei
2019-04-24 11:02 ` [PATCH V7 8/9] block: don't drain in-progress dispatch in blk_cleanup_queue() Ming Lei
2019-04-24 11:02 ` [PATCH V7 9/9] nvme: hold request queue's refcount in ns's whole lifetime Ming Lei
2019-04-24 16:27 ` Christoph Hellwig
2019-04-25 1:00 ` Ming Lei
2019-04-26 15:11 ` Christoph Hellwig
2019-04-26 17:04 ` Bart Van Assche
2019-04-26 22:49 ` Ming Lei
2019-04-26 22:45 ` Ming Lei
2019-04-27 5:54 ` Christoph Hellwig
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