linux-kernel - Re: [PATCH v7 3/3] nvme-fc: Remove freeze/unfreeze around update_nr_hw

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Date:   Tue, 14 Sep 2021 13:55:23 +0000
From:   Himanshu Madhani <himanshu.madhani@...cle.com>
To:     Daniel Wagner <dwagner@...e.de>
CC:     "linux-nvme@...ts.infradead.org" <linux-nvme@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Hannes Reinecke <hare@...e.de>,
        Sagi Grimberg <sagi@...mberg.me>,
        Keith Busch <kbusch@...nel.org>,
        Ming Lei <ming.lei@...hat.com>,
        Wen Xiong <wenxiong@...ibm.com>,
        James Smart <jsmart2021@...il.com>
Subject: Re: [PATCH v7 3/3] nvme-fc: Remove freeze/unfreeze around
 update_nr_hw_queues



> On Sep 14, 2021, at 4:20 AM, Daniel Wagner <dwagner@...e.de> wrote:
> 
> From: James Smart <jsmart2021@...il.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@...il.com>
> [dwagner: added explanation why no IO is pending]
> Signed-off-by: Daniel Wagner <dwagner@...e.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);
> -- 
> 2.29.2
> 

Looks Good.

Reviewed-by: Himanshu Madhani <himanshu.madhani@...cle.com>

--
Himanshu Madhani	 Oracle Linux Engineering