linux-kernel - Re: [PATCH v5 01/12] nvme-fc: do not wait in vain when unloading module

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Date: Thu, 1 Feb 2024 13:41:35 +0100
From: Hannes Reinecke <hare@...e.de>
To: Daniel Wagner <dwagner@...e.de>, James Smart <james.smart@...adcom.com>
Cc: Keith Busch <kbusch@...nel.org>, Christoph Hellwig <hch@....de>,
 linux-nvme@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 01/12] nvme-fc: do not wait in vain when unloading
 module

On 1/31/24 09:51, Daniel Wagner wrote:
> The module exit path has race between deleting all controllers and
> freeing 'left over IDs'. To prevent double free a synchronization
> between nvme_delete_ctrl and ida_destroy has been added by the initial
> commit.
> 
> There is some logic around trying to prevent from hanging forever in
> wait_for_completion, though it does not handling all cases. E.g.
> blktests is able to reproduce the situation where the module unload
> hangs forever.
> 
> If we completely rely on the cleanup code executed from the
> nvme_delete_ctrl path, all IDs will be freed eventually. This makes
> calling ida_destroy unnecessary. We only have to ensure that all
> nvme_delete_ctrl code has been executed before we leave
> nvme_fc_exit_module. This is done by flushing the nvme_delete_wq
> workqueue.
> 
> While at it, remove the unused nvme_fc_wq workqueue too.
> 
> Reviewed-by: Christoph Hellwig <hch@....de>
> Signed-off-by: Daniel Wagner <dwagner@...e.de>
> ---
>   drivers/nvme/host/fc.c | 47 ++++++------------------------------------
>   1 file changed, 6 insertions(+), 41 deletions(-)
> 
Reviewed-by: Hannes Reinecke <hare@...e.de>

Cheers,

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