@@ -8599,10 +8599,27 @@ EXPORT_SYMBOL(ufshcd_runtime_idle);
int ufshcd_shutdown(struct ufs_hba *hba)
{
int ret = 0;
+ struct scsi_target *starget;
if (!hba->is_powered)
goto out;
+ /*
+ * Quiesce all SCSI devices to prevent any non-PM requests sending
+ * from block layer during and after shutdown.
+ *
+ * Here we can not use blk_cleanup_queue() since PM requests
+ * (with BLK_MQ_REQ_PREEMPT flag) are still required to be sent
+ * through block layer. Therefore SCSI command queued after the
+ * scsi_target_quiesce() call returned will block until
+ * blk_cleanup_queue() is called.
+ *
+ * Besides, scsi_target_"un"quiesce (e.g., scsi_target_resume) can
+ * be ignored since shutdown is one-way flow.
+ */
+ list_for_each_entry(starget, &hba->host->__targets, siblings)
+ scsi_target_quiesce(starget);
+
if (ufshcd_is_ufs_dev_poweroff(hba) && ufshcd_is_link_off(hba))
goto out;
Currently I/O request could be still submitted to UFS device while UFS is working on shutdown flow. This may lead to racing as below scenarios and finally system may crash due to unclocked register accesses. To fix this kind of issues, specifically quiesce all SCSI devices before UFS shutdown to block all I/O request sending from block layer. Example of racing scenario: While UFS device is runtime-suspended Thread #1: Executing UFS shutdown flow, e.g., ufshcd_suspend(UFS_SHUTDOWN_PM) Thread #2: Executing runtime resume flow triggered by I/O request, e.g., ufshcd_resume(UFS_RUNTIME_PM) This breaks the assumption that UFS PM flows can not be running concurrently and some unexpected racing behavior may happen. Signed-off-by: Stanley Chu <stanley.chu@mediatek.com> --- drivers/scsi/ufs/ufshcd.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)