From: Bart Van Assche <bvanassche@acm.org>
To: Can Guo <cang@codeaurora.org>
Cc: asutoshd@codeaurora.org, nguyenb@codeaurora.org,
hongwus@codeaurora.org, ziqichen@codeaurora.org,
linux-scsi@vger.kernel.org, kernel-team@android.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>, Jaegeuk Kim <jaegeuk@kernel.org>,
open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 8/9] scsi: ufs: Update the fast abort path in ufshcd_abort() for PM requests
Date: Mon, 14 Jun 2021 11:49:10 -0700 [thread overview]
Message-ID: <8b27b0cc-ae16-173a-bd6f-0321a6aba01c@acm.org> (raw)
In-Reply-To: <75527f0ba5d315d6edbf800a2ddcf8c7@codeaurora.org>
On 6/13/21 7:42 AM, Can Guo wrote:
> 2. ufshcd_abort() invokes ufshcd_err_handler() synchronously can have a
> live lock issue, which is why I chose the asynchronous way (from the first
> day I started to fix error handling). The live lock happens when abort
> happens
> to a PM request, e.g., a SSU cmd sent from suspend/resume. Because UFS
> error
> handler is synchronized with suspend/resume (by calling
> pm_runtime_get_sync()
> and lock_system_sleep()), the sequence is like:
> [1] ufshcd_wl_resume() sends SSU cmd
> [2] ufshcd_abort() calls UFS error handler
> [3] UFS error handler calls lock_system_sleep() and pm_runtime_get_sync()
>
> In above sequence, either lock_system_sleep() or pm_runtime_get_sync()
> shall
> be blocked - [3] is blocked by [1], [2] is blocked by [3], while [1] is
> blocked by [2].
>
> For PM requests, I chose to abort them fast to unblock suspend/resume,
> suspend/resume shall fail of course, but UFS error handler recovers
> PM errors anyways.
In the above sequence, does [2] perhaps refer to aborting the SSU
command submitted in step [1] (this is not clear to me)? If so, how
about breaking the circular waiting cycle as follows:
- If it can happen that SSU succeeds after more than scsi_timeout
seconds, define a custom timeout handler. From inside the timeout
handler, schedule a link check and return BLK_EH_RESET_TIMER. If the
link is no longer operational, run the error handler. If the link
cannot be recovered by the error handler, fail all pending commands.
This will prevent that ufshcd_abort() is called if a SSU command takes
longer than expected. See also commit 0dd0dec1677e.
- Modify the UFS error handler such that it accepts a context argument.
The context argument specifies whether or not the UFS error handler is
called from inside a system suspend or system resume handler. If the
UFS error handler is called from inside a system suspend or resume
callback, skip the lock_system_sleep() and unlock_system_sleep()
calls.
Thanks,
Bart.
next prev parent reply other threads:[~2021-06-14 18:49 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-10 4:43 [PATCH v3 0/9] Complementary changes for error handling Can Guo
2021-06-10 4:43 ` [PATCH v3 1/9] scsi: ufs: Differentiate status between hba pm ops and wl pm ops Can Guo
2021-06-10 11:15 ` Adrian Hunter
2021-06-11 0:53 ` Can Guo
2021-06-11 20:40 ` Bart Van Assche
2021-06-12 6:20 ` Can Guo
2021-06-16 17:50 ` Bart Van Assche
2021-06-23 1:32 ` Can Guo
2021-06-10 4:43 ` [PATCH v3 2/9] scsi: ufs: Update the return value of supplier " Can Guo
2021-06-10 4:43 ` [PATCH v3 3/9] scsi: ufs: Enable IRQ after enabling clocks in error handling preparation Can Guo
2021-06-10 4:43 ` [PATCH v3 4/9] scsi: ufs: Complete the cmd before returning in queuecommand Can Guo
2021-06-11 20:52 ` Bart Van Assche
2021-06-12 7:38 ` Can Guo
2021-06-12 15:50 ` Bart Van Assche
2021-06-13 13:30 ` Can Guo
2021-06-10 4:43 ` [PATCH v3 5/9] scsi: ufs: Simplify error handling preparation Can Guo
2021-06-10 12:30 ` Adrian Hunter
2021-06-11 3:01 ` Can Guo
2021-06-11 20:58 ` Bart Van Assche
2021-06-12 6:46 ` Can Guo
2021-06-12 9:49 ` Can Guo
2021-06-10 4:43 ` [PATCH v3 6/9] scsi: ufs: Update ufshcd_recover_pm_error() Can Guo
2021-06-10 4:43 ` [PATCH v3 7/9] scsi: ufs: Let host_sem cover the entire system suspend/resume Can Guo
2021-06-10 13:32 ` Adrian Hunter
2021-06-11 3:06 ` Can Guo
2021-06-11 21:00 ` Bart Van Assche
2021-06-12 6:46 ` Can Guo
2021-06-10 4:43 ` [PATCH v3 8/9] scsi: ufs: Update the fast abort path in ufshcd_abort() for PM requests Can Guo
2021-06-11 21:02 ` Bart Van Assche
2021-06-12 7:07 ` Can Guo
2021-06-12 16:50 ` Bart Van Assche
2021-06-13 14:42 ` Can Guo
2021-06-14 18:49 ` Bart Van Assche [this message]
2021-06-15 2:36 ` Can Guo
2021-06-15 3:17 ` Can Guo
2021-06-15 18:25 ` Bart Van Assche
2021-06-16 4:00 ` Can Guo
2021-06-16 4:40 ` Bart Van Assche
2021-06-16 8:47 ` Can Guo
2021-06-16 17:55 ` Bart Van Assche
2021-06-23 1:34 ` Can Guo
2021-06-10 4:43 ` [PATCH v3 9/9] scsi: ufs: Apply more limitations to user access Can Guo
2021-06-11 21:03 ` Bart Van Assche
2021-06-12 7:13 ` Can Guo
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