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Subject: Re: [PATCH v7 3/3] nvme-fc: Remove freeze/unfreeze around
 update_nr_hw_queues
To:     Daniel Wagner <dwagner@suse.de>, linux-nvme@lists.infradead.org
Cc:     linux-kernel@vger.kernel.org, Sagi Grimberg <sagi@grimberg.me>,
        Keith Busch <kbusch@kernel.org>,
        Ming Lei <ming.lei@redhat.com>,
        Wen Xiong <wenxiong@us.ibm.com>,
        Himanshu Madhani <himanshu.madhani@oracle.com>,
        James Smart <jsmart2021@gmail.com>
References: <20210914092008.40370-1-dwagner@suse.de>
 <20210914092008.40370-4-dwagner@suse.de>
From:   Hannes Reinecke <hare@suse.de>
Message-ID: <040a7eef-3603-2d8f-0576-3fceafc80de8@suse.de>
Date:   Tue, 14 Sep 2021 12:58:12 +0200
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On 9/14/21 11:20 AM, Daniel Wagner wrote:
> From: James Smart <jsmart2021@gmail.com>
> 
> Remove the freeze/unfreeze around changes to the number of hardware
> queues. Study and retest has indicated there are no ios that can be
> active at this point so there is nothing to freeze.
> 
> nvme-fc is draining the queues in the shutdown and error recovery path
> in __nvme_fc_abort_outstanding_ios.
> 
> This patch primarily reverts 88e837ed0f1f "nvme-fc: wait for queues to
> freeze before calling update_hr_hw_queues". It's not an exact revert as
> it leaves the adjusting of hw queues only if the count changes.
> 
> Signed-off-by: James Smart <jsmart2021@gmail.com>
> [dwagner: added explanation why no IO is pending]
> Signed-off-by: Daniel Wagner <dwagner@suse.de>
> ---
>  drivers/nvme/host/fc.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
> index 6ebe68396712..aa14ad963d91 100644
> --- a/drivers/nvme/host/fc.c
> +++ b/drivers/nvme/host/fc.c
> @@ -2957,9 +2957,7 @@ nvme_fc_recreate_io_queues(struct nvme_fc_ctrl *ctrl)
>  		dev_info(ctrl->ctrl.device,
>  			"reconnect: revising io queue count from %d to %d\n",
>  			prior_ioq_cnt, nr_io_queues);
> -		nvme_wait_freeze(&ctrl->ctrl);
>  		blk_mq_update_nr_hw_queues(&ctrl->tag_set, nr_io_queues);
> -		nvme_unfreeze(&ctrl->ctrl);
>  	}
>  
>  	ret = nvme_fc_create_hw_io_queues(ctrl, ctrl->ctrl.sqsize + 1);
> 
Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		           Kernel Storage Architect
hare@suse.de			                  +49 911 74053 688
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