• Stanley Chu's avatar
    scsi: core: Synchronize request queue PM status only on successful resume · 3f7e62bb
    Stanley Chu authored
    The commit 356fd266 ("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.
    
    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: 356fd266 (scsi: Set request queue runtime PM status back to active on resume)
    Cc: stable@vger.kernel.org
    Signed-off-by: default avatarStanley Chu <stanley.chu@mediatek.com>
    Reviewed-by: default avatarBart Van Assche <bvanassche@acm.org>
    Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
    3f7e62bb
scsi_pm.c 8.2 KB