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To:     Can Guo <cang@codeaurora.org>
Cc:     asutoshd@codeaurora.org, nguyenb@codeaurora.org,
        hongwus@codeaurora.org, rnayak@codeaurora.org,
        linux-scsi@vger.kernel.org, kernel-team@android.com,
        saravanak@google.com, salyzyn@google.com,
        Alim Akhtar <alim.akhtar@samsung.com>,
        Avri Altman <avri.altman@wdc.com>,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Stanley Chu <stanley.chu@mediatek.com>,
        Bean Huo <beanhuo@micron.com>,
        Bart Van Assche <bvanassche@acm.org>,
        linux-kernel@vger.kernel.org (open list)
Subject: Re: [PATCH v9 8/9] scsi: ufs: Fix a racing problem btw error
 handler and runtime PM ops
From:   "Martin K. Petersen" <martin.petersen@oracle.com>
Organization: Oracle Corporation
Message-ID: <yq1r1slzxoh.fsf@ca-mkp.ca.oracle.com>
References: <1596445485-19834-1-git-send-email-cang@codeaurora.org>
        <1596445485-19834-9-git-send-email-cang@codeaurora.org>
Date:   Tue, 04 Aug 2020 21:31:13 -0400
In-Reply-To: <1596445485-19834-9-git-send-email-cang@codeaurora.org> (Can
        Guo's message of "Mon, 3 Aug 2020 02:04:43 -0700")
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Can,

> Current IRQ handler blocks scsi requests before scheduling eh_work,
> when error handler calls pm_runtime_get_sync, if ufshcd_suspend/resume
> sends a scsi cmd, most likely the SSU cmd, since scsi requests are
> blocked, pm_runtime_get_sync() will never return because
> ufshcd_suspend/reusme is blocked by the scsi cmd. Some changes and
> code re-arrangement can be made to resolve it.

  CC [M]  drivers/scsi/ufs/ufshcd.o
drivers/scsi/ufs/ufshcd.c: In function =E2=80=98ufshcd_queuecommand=E2=80=
=99:
drivers/scsi/ufs/ufshcd.c:2570:6: error: this statement may fall through [-=
Werror=3Dimplicit-fallthrough=3D]
 2570 |   if (hba->pm_op_in_progress) {
      |      ^
drivers/scsi/ufs/ufshcd.c:2575:2: note: here
 2575 |  case UFSHCD_STATE_RESET:
      |  ^~~~
cc1: all warnings being treated as errors
make[3]: *** [scripts/Makefile.build:280: drivers/scsi/ufs/ufshcd.o] Error 1
make[2]: *** [scripts/Makefile.build:497: drivers/scsi/ufs] Error 2
make[1]: *** [scripts/Makefile.build:497: drivers/scsi] Error 2
make: *** [Makefile:1764: drivers] Error 2

--=20
Martin K. Petersen	Oracle Linux Engineering