[PATCH v2 2/2] scsi: ufs: core: Do not recover the link concurrently with a PM callback

[Stanley Jhu <stanleyjhu@google.com>]

From: Brian Kao <powenkao@google.com>

ufshcd_set_dev_pwr_mode() now recovers the link after a START STOP
UNIT timeout. ufshcd_err_handler() must not recover the link while a
PM callback runs. Its pm_op_in_progress branch still does so when a
fatal UIC error arrives during that recovery.

Remove the pm_op_in_progress branch, so ufshcd_err_handler() waits
for the callback and only one context enables the host controller.

1. Runtime suspend sends START STOP UNIT and the device does not
   answer.
2. ufshcd_set_dev_pwr_mode() starts link recovery after the timeout.
3. A fatal UIC error queues ufshcd_err_handler().
4. ufshcd_err_handler() sees pm_op_in_progress and starts a second
   link recovery. Both enable the host controller at once.

Removing the pm_op_in_progress branch needs one more change. A fatal
error during runtime resume then has no recovery:

1. A fatal UIC error queues ufshcd_err_handler(), which waits for
   the runtime resume.
2. START STOP UNIT fails with DID_BAD_TARGET and resume fails.
3. ufshcd_err_handler() resumes again and fails the same way. The
   block layer pm_only count underflows and I/O hangs.

Recover the link in __ufshcd_wl_resume() when START STOP UNIT fails
while error handling is scheduled for a fatal error, as it does after
a failed hibern8 exit.

Fixes: f966e02ae521 ("scsi: ufs: core: Fix runtime suspend error deadlock")
Fixes: e23ef4f22db3 ("scsi: ufs: core: Fix error handler host_sem issue")
Cc: stable@vger.kernel.org # 7.2.x
Signed-off-by: Brian Kao <powenkao@google.com>
[stanleyjhu: recover the link in __ufshcd_wl_resume() after a
 fatal error]
Signed-off-by: Stanley Jhu <stanleyjhu@google.com>
---
 drivers/ufs/core/ufshcd.c | 19 ++-----------------
 1 file changed, 2 insertions(+), 17 deletions(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 0f5365bd90f0..825906b643fa 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -7074,23 +7074,6 @@ static void ufshcd_err_handler(struct work_struct *work)
 		 hba->saved_uic_err, hba->force_reset,
 		 ufshcd_is_link_broken(hba) ? "; link is broken" : "");
 
-	if (hba->ufs_device_wlun) {
-		/*
-		 * Use ufshcd_rpm_get_noresume() here to safely perform link
-		 * recovery even if an error occurs during runtime suspend or
-		 * runtime resume. This avoids potential deadlocks that could
-		 * happen if we tried to resume the device while a PM operation
-		 * is already in progress.
-		 */
-		ufshcd_rpm_get_noresume(hba);
-		if (hba->pm_op_in_progress) {
-			ufshcd_link_recovery(hba);
-			ufshcd_rpm_put(hba);
-			return;
-		}
-		ufshcd_rpm_put(hba);
-	}
-
 	down(&hba->host_sem);
 	spin_lock_irqsave(&hba->host->host_lock, flags);
 	if (ufshcd_err_handling_should_stop(hba)) {
@@ -10638,6 +10621,8 @@ static int __ufshcd_wl_resume(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 
 	if (!ufshcd_is_ufs_dev_active(hba)) {
 		ret = ufshcd_set_dev_pwr_mode(hba, UFS_ACTIVE_PWR_MODE);
+		if (ret && hba->ufshcd_state == UFSHCD_STATE_EH_SCHEDULED_FATAL)
+			ret = ufshcd_link_recovery(hba);
 		if (ret)
 			goto set_old_link_state;
 		ufshcd_set_timestamp_attr(hba);
-- 
2.56.0.611.g1030f0b940-goog