From: "Nadolski, Edmund" <edmund.nadolski@intel.com>
To: Keith Busch <kbusch@kernel.org>,
"Nadolski, Edmund" <edmund.nadolski@intel.com>
Cc: Christoph Hellwig <hch@lst.de>, linux-nvme@lists.infradead.org
Subject: Re: [PATCH] nvme: clear stale nvmeq->tags after tagset free
Date: Tue, 21 Jan 2020 11:49:53 -0700 [thread overview]
Message-ID: <0fd26a56-d57c-eeae-52b0-a80b64943bdb@intel.com> (raw)
In-Reply-To: <20200121174235.GA4954@redsun51.ssa.fujisawa.hgst.com>
On 1/21/2020 10:42 AM, Keith Busch wrote:
> On Tue, Jan 21, 2020 at 10:32:22AM -0700, Nadolski, Edmund wrote:
>> The tagset pointer gets invalidated when the driver calls the following:
>>
>> nvme_reset_work()
>> +-> nvme_setup_io_queues() <<< cmd fails, no io queues created
>> +-> nvme_kill_queues()
>> +-> nvme_remove_namespaces()
>> | +-> nvme_ns_remove() <<< for each ctrl->namespaces
>> | +-> del_gendisk()
>> | +-> blk_cleanup_queue()
>> | | +-> blk_mq_exit_queue() <<< invalidates the tags
>> | | +-> blk_mq_del_queue_tag_set()
>> | | +-> blk_mq_exit_hw_queues()
>> | | +-> blk_mq_exit_hctx()
>> | | +-> set->ops->exit_hctx(...) <<< driver callback
>> | +-> nvme_put_ns()
>> +-> nvme_free_tagset()
>> | +-> blk_mq_free_tagset()
>> +-> nvme_start_ctrl() <<< allow operation w/o namespaces
>>
>> So the nvmeq->tags is already dead and stale by the time we get to
>> nvme_free_tagset.
>
> No, nvmeq->tags is not stale until we call nvme_free_tagset().
I see this in blk/blk-mq.c:
2943 /* tags can _not_ be used after returning from blk_mq_exit_queue */
2944 void blk_mq_exit_queue(struct request_queue *q)
which ends up being called on every individual ctrl->namespaces entry. What
have I overlooked?
Thanks for clarifying,
Ed
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next prev parent reply other threads:[~2020-01-21 18:50 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-14 18:17 [PATCH] nvme: clear stale nvmeq->tags after tagset free Edmund Nadolski
2020-01-16 16:06 ` Keith Busch
2020-01-16 22:06 ` Nadolski, Edmund
2020-01-16 23:26 ` Keith Busch
2020-01-21 17:32 ` Nadolski, Edmund
2020-01-21 17:42 ` Keith Busch
2020-01-21 18:49 ` Nadolski, Edmund [this message]
2020-01-21 19:12 ` Keith Busch
2020-01-21 19:26 ` Nadolski, Edmund
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