linux-kernel - Re: [PATCH v5 6/7] module: Improve support for asynchronous module exit code

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Message-ID: <67e70e00-3a79-c8b0-525a-92071a015366@acm.org>
Date:   Thu, 29 Sep 2022 10:27:16 -0700
From:   Bart Van Assche <bvanassche@....org>
To:     Ming Lei <ming.lei@...hat.com>
Cc:     "Martin K . Petersen" <martin.petersen@...cle.com>,
        linux-scsi@...r.kernel.org, Luis Chamberlain <mcgrof@...nel.org>,
        Christoph Hellwig <hch@....de>, Hannes Reinecke <hare@...e.de>,
        John Garry <john.garry@...wei.com>,
        Mike Christie <michael.christie@...cle.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-modules@...r.kernel.org, linux-kernel@...r.kernel.org,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        Tejun Heo <tj@...nel.org>
Subject: Re: [PATCH v5 6/7] module: Improve support for asynchronous module
 exit code

On 9/28/22 18:10, Ming Lei wrote:
> On Wed, Sep 28, 2022 at 12:27:07PM -0700, Bart Van Assche wrote:
>> How about removing support for calling scsi_device_put() from atomic context
>> as is done in the untested patch below?
> 
> That can't work.
> 
> The problem is that no existed mechanism can guarantee that kobject reference
> drops to zero inside module_exit().

Hi Ming,

I agree that the patch in my previous email won't address potential calls of
.release functions while a module is being unloaded or after a module has been
unloaded. However, that's not the purpose of that patch. The purpose of that
patch is to rework all code that modifies members of the scsi host template.

Thanks,

Bart.