From: Sagi Grimberg <sagi@grimberg.me>
To: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>, Keith Busch <kbusch@kernel.org>,
Chao Leng <lengchao@huawei.com>, Ming Lei <ming.lei@redhat.com>,
linux-nvme@lists.infradead.org, linux-block@vger.kernel.org
Subject: Re: [PATCH 6/8] nvme: move the NS_DEAD flag to the controller
Date: Mon, 24 Oct 2022 11:43:08 +0300 [thread overview]
Message-ID: <7d93b4fe-f88b-2d2c-e58d-396e03f3bc72@grimberg.me> (raw)
In-Reply-To: <20221021132815.GE22327@lst.de>
>>> -
>>> + if (!test_and_set_bit(NVME_CTRL_NS_DEAD, &ctrl->flags)) {
>>> + list_for_each_entry(ns, &ctrl->namespaces, list)
>>> + nvme_set_queue_dying(ns);
>>> + }
>>
>> Looking at it now, I'm not sure I understand the need for this flag. It
>> seems to make nvme_kill_queues reentrant safe, but the admin queue
>> unquiesce can still end up unbalanced under reentrance?
>>
>> How is this not broken today (or ever since quiesce/unquiesce started
>> accounting)? Maybe I lost some context on the exact subtlety of how
>> nvme-pci uses this interface...
>
> Yes, this also looks weird and I had a TODO list entry for myself
> to look into what is going on here. The whole interaction
> with nvme_remove_namespaces is pretty weird to start with, and then
> the code in PCIe is even more weird. But to feel confident to
> touch this I'd need real hot removal testing, for which I don't
> have a good rig right now.
Lets for start move the bit check up in the function and reverse
the polarity to return if it is set. Unless someone can make sense
of why this is OK.
next prev parent reply other threads:[~2022-10-24 8:43 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-20 10:56 per-tagset SRCU struct and quiesce Christoph Hellwig
2022-10-20 10:56 ` [PATCH 1/8] block: set the disk capacity to 0 in blk_mark_disk_dead Christoph Hellwig
2022-10-20 13:16 ` Sagi Grimberg
2022-10-21 1:09 ` Ming Lei
2022-10-21 13:11 ` Christoph Hellwig
2022-10-21 1:53 ` Chao Leng
2022-10-21 6:49 ` Hannes Reinecke
2022-10-21 13:13 ` Christoph Hellwig
2022-10-21 21:12 ` Bart Van Assche
2022-10-20 10:56 ` [PATCH 2/8] blk-mq: skip non-mq queues in blk_mq_quiesce_queue Christoph Hellwig
2022-10-20 13:16 ` Sagi Grimberg
2022-10-21 1:13 ` Ming Lei
2022-10-21 13:19 ` Christoph Hellwig
2022-10-21 15:08 ` Ming Lei
2022-10-21 2:47 ` Chao Leng
2022-10-21 3:16 ` Chao Leng
2022-10-21 6:49 ` Hannes Reinecke
2022-10-20 10:56 ` [PATCH 3/8] blk-mq: move the srcu_struct used for quiescing to the tagset Christoph Hellwig
2022-10-20 13:23 ` Sagi Grimberg
2022-10-20 17:26 ` Keith Busch
2022-10-21 13:20 ` Christoph Hellwig
2022-10-21 1:41 ` Ming Lei
2022-10-21 2:49 ` Chao Leng
2022-10-21 6:50 ` Hannes Reinecke
2022-10-21 7:16 ` Chao Leng
2022-10-21 13:22 ` Christoph Hellwig
2022-10-20 10:56 ` [PATCH 4/8] blk-mq: pass a tagset to blk_mq_wait_quiesce_done Christoph Hellwig
2022-10-20 13:23 ` Sagi Grimberg
2022-10-21 1:46 ` Ming Lei
2022-10-21 13:23 ` Christoph Hellwig
2022-10-21 2:49 ` Chao Leng
2022-10-21 6:50 ` Hannes Reinecke
2022-10-21 21:18 ` Bart Van Assche
2022-10-20 10:56 ` [PATCH 5/8] blk-mq: add tagset quiesce interface Christoph Hellwig
2022-10-20 13:24 ` Sagi Grimberg
2022-10-21 1:53 ` Ming Lei
2022-10-21 2:49 ` Chao Leng
2022-10-21 6:51 ` Hannes Reinecke
2022-10-21 21:22 ` Bart Van Assche
2022-10-24 1:57 ` Chao Leng
2022-10-24 13:35 ` Bart Van Assche
2022-10-25 1:38 ` Chao Leng
2022-10-20 10:56 ` [PATCH 6/8] nvme: move the NS_DEAD flag to the controller Christoph Hellwig
2022-10-20 13:30 ` Sagi Grimberg
2022-10-21 13:28 ` Christoph Hellwig
2022-10-24 8:43 ` Sagi Grimberg [this message]
2022-10-24 8:50 ` Sagi Grimberg
2022-10-21 2:49 ` Chao Leng
2022-10-21 6:51 ` Hannes Reinecke
2022-10-20 10:56 ` [PATCH 7/8] nvme: remove nvme_set_queue_dying Christoph Hellwig
2022-10-20 13:10 ` Sagi Grimberg
2022-10-21 13:29 ` Christoph Hellwig
2022-10-24 8:48 ` Sagi Grimberg
2022-10-21 2:50 ` Chao Leng
2022-10-21 6:52 ` Hannes Reinecke
2022-10-20 10:56 ` [PATCH 8/8] nvme: use blk_mq_[un]quiesce_tagset Christoph Hellwig
2022-10-20 13:35 ` Sagi Grimberg
2022-10-21 2:50 ` Chao Leng
2022-10-21 6:52 ` Hannes Reinecke
2022-10-20 13:16 ` per-tagset SRCU struct and quiesce Sagi Grimberg
2022-10-21 18:06 ` Keith Busch
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