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From: Christoph Hellwig <hch@infradead.org>
To: John Garry <john.garry@huawei.com>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
	Christoph Hellwig <hch@infradead.org>,
	"Ewan D. Milne" <emilne@redhat.com>,
	"James E.J. Bottomley" <jejb@linux.ibm.com>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	Alim Akhtar <alim.akhtar@samsung.com>,
	Avri Altman <avri.altman@wdc.com>,
	Doug Gilbert <dgilbert@interlog.com>,
	linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org,
	james.smart@broadcom.com
Subject: Re: [PATCH 1/4] scsi: core: constify pointer to scsi_host_template
Date: Wed, 11 May 2022 01:31:36 -0700	[thread overview]
Message-ID: <Ynt0aFMX+z/UhGJ2@infradead.org> (raw)
In-Reply-To: <fd2cdc06-5d88-306a-3ee1-7aef3e3b8921@huawei.com>

On Mon, May 09, 2022 at 03:50:33PM +0100, John Garry wrote:
> If you check scsi_device_dev_release(), we try to do a 'get' - if it fails,
> then we nullify hostt->module. I think that is important as then we call
> execute_in_process_context(), whose worker does the 'put'. However, the
> 'put' will get upset if the refcnt was 0, which it would be if the earlier
> 'get' fails - hence the nullify is to avoid that possibility. So whatever
> you do needs to handle that. Details are in f2b85040

Yikes, that code is completely and utterly buggy and does not account
for all the cases why try_module_get can fail.  I think we always have
a reference here and could use __module_get, but what we have is
certainly unsafe and a good reason why the host template should be
constifyed.

      reply	other threads:[~2022-05-11  8:33 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-08 10:30 [PATCH 1/4] scsi: core: constify pointer to scsi_host_template Krzysztof Kozlowski
2022-04-08 10:30 ` [PATCH 2/4] scsi: core: fix white-spaces Krzysztof Kozlowski
2022-05-04  8:47   ` Krzysztof Kozlowski
2022-04-08 10:30 ` [PATCH 3/4] scsi: ufs: ufshcd-pltfrm: constify pointed data Krzysztof Kozlowski
2022-04-08 10:30 ` [PATCH 4/4] scsi: ufs: ufshcd: " Krzysztof Kozlowski
2022-04-08 14:35   ` Bart Van Assche
2022-04-08 12:14 ` [PATCH 1/4] scsi: core: constify pointer to scsi_host_template John Garry
2022-04-08 12:32   ` Krzysztof Kozlowski
2022-04-08 12:57     ` John Garry
2022-04-08 19:31       ` Ewan D. Milne
2022-04-12  7:57         ` John Garry
2022-04-20  7:03           ` Christoph Hellwig
2022-04-25  8:58             ` John Garry
2022-04-25  9:22               ` Krzysztof Kozlowski
2022-04-25 13:04                 ` John Garry
2022-04-26  1:16                   ` Bart Van Assche
2022-04-26  1:54                     ` Douglas Gilbert
2022-04-26  4:13                       ` Bart Van Assche
2022-04-27  1:47                         ` Douglas Gilbert
2022-05-06 16:42                   ` Krzysztof Kozlowski
2022-05-09 11:28                     ` John Garry
2022-05-09 13:20                       ` Krzysztof Kozlowski
2022-05-09 14:50                         ` John Garry
2022-05-11  8:31                           ` Christoph Hellwig [this message]

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