Re: [PATCH v3 15/18] scsi: ufs: Request sense data asynchronously

From: Bean Huo <huobean@gmail.com>
To: Bart Van Assche <bvanassche@acm.org>,
	"Martin K . Petersen" <martin.petersen@oracle.com>
Cc: linux-scsi@vger.kernel.org, Jaegeuk Kim <jaegeuk@kernel.org>,
	Adrian Hunter <adrian.hunter@intel.com>,
	Stanley Chu <stanley.chu@mediatek.com>,
	Can Guo <cang@codeaurora.org>,
	Asutosh Das <asutoshd@codeaurora.org>,
	Avri Altman <avri.altman@wdc.com>,
	"James E.J. Bottomley" <jejb@linux.ibm.com>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	Bean Huo <beanhuo@micron.com>
Subject: Re: [PATCH v3 15/18] scsi: ufs: Request sense data asynchronously
Date: Mon, 02 Aug 2021 15:16:39 +0200	[thread overview]
Message-ID: <644b3783c170defc89fb6aa4844b30ccd10a6c01.camel@gmail.com> (raw)
In-Reply-To: <20210722033439.26550-16-bvanassche@acm.org>

On Wed, 2021-07-21 at 20:34 -0700, Bart Van Assche wrote:
> Clearing a unit attention synchronously from inside the UFS error
> handler
> may trigger the following deadlock:
> - ufshcd_err_handler() calls ufshcd_err_handling_unprepare() and the
> latter
>   function calls ufshcd_clear_ua_wluns().
> - ufshcd_clear_ua_wluns() submits a REQUEST SENSE command and that
> command
>   activates the SCSI error handler.
> - The SCSI error handler calls ufshcd_host_reset_and_restore().
> - ufshcd_host_reset_and_restore() executes the following code:
>   ufshcd_schedule_eh_work(hba);
>   flush_work(&hba->eh_work);
> 
> This sequence results in a deadlock (circular wait). Fix this by
> requesting
> sense data asynchronously.
> 
> Cc: Adrian Hunter <adrian.hunter@intel.com>
> Cc: Stanley Chu <stanley.chu@mediatek.com>
> Cc: Can Guo <cang@codeaurora.org>
> Cc: Asutosh Das <asutoshd@codeaurora.org>
> Cc: Avri Altman <avri.altman@wdc.com>
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>

Reviewed-by: Bean Huo <beanhuo@micron.com>