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

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Message-ID: <a4084b27-dd2d-10df-493c-35998eed664c@acm.org>
Date:   Tue, 20 Sep 2022 10:13:40 -0700
From:   Bart Van Assche <bvanassche@....org>
To:     Luis Chamberlain <mcgrof@...nel.org>
Cc:     "Martin K . Petersen" <martin.petersen@...cle.com>,
        linux-scsi@...r.kernel.org, Christoph Hellwig <hch@....de>,
        Ming Lei <ming.lei@...hat.com>, 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 9/14/22 15:56, Bart Van Assche wrote:
> Some kernel modules call device_del() from their module exit code and
> schedule asynchronous work from inside the .release callback without waiting
> until that callback has finished. As an example, many SCSI LLD drivers call
> scsi_remove_host() from their module exit code. scsi_remove_host() may
> invoke scsi_device_dev_release_usercontext() asynchronously.
> scsi_device_dev_release_usercontext() uses the host template pointer and
> that pointer usually exists in static storage in the SCSI LLD. Support
> using the module reference count to keep the module around until
> asynchronous module exiting has completed by waiting in the delete_module()
> system call until the module reference count drops to zero.

Hi Luis,

I'd like to know your opinion about this patch since you are the 
maintainer of the kernel module system.

Thanks,

Bart.