Hi Mika,
On Thu, 2019-01-03 at 10:23 +0200, Mika Westerberg wrote:
Hi,
On Thu, Jan 03, 2019 at 02:53:15PM +0800, stanley.chu@mediatek.com wrote:
From: Stanley Chu stanley.chu@mediatek.com
The commit 356fd2663cff ("scsi: Set request queue runtime PM status back to active on resume") fixed up the inconsistent RPM status between request queue and device. However changing request queue RPM status shall be done only on successful resume, otherwise status may be still inconsistent as below,
Request queue: RPM_ACTIVE Device: RPM_SUSPENDED
This ends up soft lockup because requests can be submitted to underlying devices but those devices and their required resource are not resumed.
It would be good to add some example of the soft lockup you are seeing here.
Thanks for remind, I will add below example in commit message in v3.
For example,
After above inconsistent status happens, IO request can be submitted to UFS device driver but required resource (like clock) is not resumed yet thus lead to warning as below call stack,
WARN_ON(hba->clk_gating.state != CLKS_ON); ufshcd_queuecommand scsi_dispatch_cmd scsi_request_fn __blk_run_queue cfq_insert_request __elv_add_request blk_flush_plug_list blk_finish_plug jbd2_journal_commit_transaction kjournald2
We may see all behind IO requests hang because of no response from storage host or device and then soft lockup happens in system. In the end, system may crash in many ways.
Fixes: 356fd2663cff ("scsi: Set request queue runtime PM status back to active on resume")
You don't need to wrap this.
OK! Will fix it.
The change itself looks fine.
Thanks.
Stanley
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