From: Can Guo <cang@codeaurora.org>
To: Bart Van Assche <bvanassche@acm.org>
Cc: asutoshd@codeaurora.org, nguyenb@codeaurora.org,
hongwus@codeaurora.org, linux-scsi@vger.kernel.org,
kernel-team@android.com, Stanley Chu <stanley.chu@mediatek.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>,
Matthias Brugger <matthias.bgg@gmail.com>,
Bean Huo <beanhuo@micron.com>, Jaegeuk Kim <jaegeuk@kernel.org>,
Adrian Hunter <adrian.hunter@intel.com>,
Kiwoong Kim <kwmad.kim@samsung.com>,
Satya Tangirala <satyat@google.com>,
open list <linux-kernel@vger.kernel.org>,
"moderated list:ARM/Mediatek SoC support"
<linux-arm-kernel@lists.infradead.org>,
"moderated list:ARM/Mediatek SoC support"
<linux-mediatek@lists.infradead.org>
Subject: Re: [PATCH v1 2/3] scsi: ufs: Optimize host lock on transfer requests send/compl paths
Date: Wed, 23 Jun 2021 10:04:39 +0800 [thread overview]
Message-ID: <e8de57b920c9246f5a41aa44c5a4fc36@codeaurora.org> (raw)
In-Reply-To: <a29164e1-ab7d-6dbc-0fb9-029f203de735@acm.org>
Hi Bart,
On 2021-06-17 10:49, Bart Van Assche wrote:
> On 5/24/21 1:36 AM, Can Guo wrote:
>> @@ -2688,6 +2705,43 @@ static int ufshcd_queuecommand(struct Scsi_Host
>> *host, struct scsi_cmnd *cmd)
>> + case UFSHCD_STATE_EH_SCHEDULED_FATAL:
>> + /*
>> + * pm_runtime_get_sync() is used at error handling preparation
>> + * stage. If a scsi cmd, e.g. the SSU cmd, is sent from hba's
>> + * PM ops, it can never be finished if we let SCSI layer keep
>> + * retrying it, which gets err handler stuck forever. Neither
>> + * can we let the scsi cmd pass through, because UFS is in bad
>> + * state, the scsi cmd may eventually time out, which will get
>> + * err handler blocked for too long. So, just fail the scsi cmd
>> + * sent from PM ops, err handler can recover PM error anyways.
>> + */
>> + if (hba->pm_op_in_progress) {
>> + hba->force_reset = true;
>> + set_host_byte(cmd, DID_BAD_TARGET);
>> + cmd->scsi_done(cmd);
>> + goto out;
>> + }
>> + fallthrough;
>
> Hi Can,
>
> I know that this patch only moves the above code and that the above
> code
> has not been introduced by this patch. Anyway, is my understanding
> correct that ufshcd_err_handler() can change the host controller state
> from UFSHCD_STATE_EH_SCHEDULED_FATAL into UFSHCD_STATE_RESET and next
> into UFSHCD_STATE_OPERATIONAL? If so, if the above code completes a
> READ
> with status DID_BAD_TARGET and if recovery by the error handler
> succeeds, will that cause the filesystem above the UFS driver to change
> into read-only mode? If the above code completes a WRITE with status
> DID_BAD_TARGET, will that cause data corruption? Is there any other
> solution to prevent data corruption than merging the
> UFSHCD_STATE_EH_SCHEDULED_FATAL and UFSHCD_STATE_EH_SCHEDULED_NON_FATAL
> back into a single state and changing the ufshcd_rpm_get_sync(hba) call
> in ufshcd_err_handling_prepare() into a pm_runtime_get_noresume() call?
>
Here, when hba->pm_op_in_progress is true, there cannot be READ or WRITE
command since hba is resuming or suspending. When fatal erorr happens,
the
DID_BAD_TARGET above is intend to let the SSU (or whatever PM requests
blocking suspend/resume) fail fast (neither returning HOST_BUSY nor
letting
the cmd pass through can achieve such purpose), so that error handling
prepare
won't get stuck [1] when it calls
lock_system_sleep()
runtime_pm_get_sync()
The reason why I split UFSHCD_STATE_EH_SCHEDULED to
UFSHCD_STATE_EH_SCHEDULED_FATAL
and UFSHCD_STATE_EH_SCHEDULED_NON_FATAL is that
1. For non-fatal errors, HW can recover by itself, so when host state is
UFSHCD_STATE_EH_SCHEDULED_NON_FATAL, cmd can still passthrough.
2. When non-fatal error (LINE-RESET for example) happens, error handler
only
needs to do a power mode transition without a full reset. If we only
have one
state, returning HOST_BUSY will get error handling prepare stuck [1],
while
fast failing SSU cmds shall make error handler do a full reset (which
goes
too far for non-fatal errors).
Thanks,
Can Guo.
> Thanks,
>
> Bart.
next prev parent reply other threads:[~2021-06-23 2:05 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-24 8:36 [PATCH v1 0/3] Optimize host lock on TR send/compl paths and utilize UTRLCNR Can Guo
2021-05-24 8:36 ` [PATCH v1 1/3] scsi: ufs: Remove a redundant command completion logic in error handler Can Guo
2021-05-24 16:43 ` Bart Van Assche
2021-05-25 4:15 ` Stanley Chu
2021-05-31 7:14 ` Bean Huo
2021-05-24 8:36 ` [PATCH v1 2/3] scsi: ufs: Optimize host lock on transfer requests send/compl paths Can Guo
2021-05-24 11:25 ` kernel test robot
2021-06-08 17:53 ` Nathan Chancellor
2021-06-09 1:01 ` Can Guo
2021-05-24 20:10 ` Bart Van Assche
2021-05-25 1:34 ` Asutosh Das (asd)
2021-05-25 8:24 ` Avri Altman
2021-05-28 7:30 ` Avri Altman
2021-06-02 21:18 ` Asutosh Das (asd)
2021-05-25 1:40 ` Can Guo
2021-05-25 16:40 ` Bart Van Assche
2021-05-31 16:04 ` Bean Huo
2021-06-02 2:14 ` Can Guo
2021-06-03 0:18 ` Bart Van Assche
2021-06-03 2:54 ` Stanley Chu
2021-06-04 1:49 ` Can Guo
2021-06-17 2:49 ` Bart Van Assche
2021-06-23 2:04 ` Can Guo [this message]
2021-06-28 22:58 ` Bart Van Assche
2021-06-29 5:41 ` Can Guo
2021-07-01 15:57 ` Bart Van Assche
2021-05-24 8:36 ` [PATCH v1 3/3] scsi: ufs: Utilize Transfer Request List Completion Notification Register Can Guo
2021-05-31 16:05 ` Bean Huo
2021-06-03 2:54 ` Stanley Chu
2021-06-16 3:48 ` [PATCH v1 0/3] Optimize host lock on TR send/compl paths and utilize UTRLCNR Martin K. Petersen
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