[PATCH 1/1] scsi: ufs: core: Fix EH failure after wlun resume error

[Po-Wen Kao <powenkao@google.com>]

From: Brian Kao <powenkao@google.com>

When a W-LUN resume fails, its parent devices in the SCSI hierarchy,
including the scsi_target, may be runtime suspended. Subsequently, the
error handler in ufshcd_recover_pm_error() fails to set the W-LUN
device back to active because the parent target is not active.
This results in the following errors:

  google-ufshcd 3c2d0000.ufs: ufshcd_err_handler started; HBA state eh_fatal; ...
  ufs_device_wlun 0:0:0:49488: START_STOP failed for power mode: 1, result 40000
  ufs_device_wlun 0:0:0:49488: ufshcd_wl_runtime_resume failed: -5
  ...
  ufs_device_wlun 0:0:0:49488: runtime PM trying to activate child device 0:0:0:49488 but parent (target0:0:0) is not active

This patch addresses this by:

1.  Ensuring the W-LUN's parent scsi_target is runtime resumed before
attempting to set the W-LUN to active within ufshcd_recover_pm_error().
2.  Explicitly checking for power.runtime_error on the HBA and W-LUN
devices before calling pm_runtime_set_active() to clear the error state.
3.  Adding pm_runtime_get_sync(hba->dev) in
ufshcd_err_handling_prepare() to ensure the HBA itself
is active during error recovery, even if a child device resume failed.

These changes ensure the device power states are managed correctly
during error recovery.

Signed-off-by: Brian Kao <powenkao@google.com>
Tested-by: Brian Kao <powenkao@google.com>
---
 drivers/ufs/core/ufshcd.c | 36 ++++++++++++++++++++++++++++--------
 1 file changed, 28 insertions(+), 8 deletions(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index fc4d1b6576dc..9176d7ce25b4 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -6504,6 +6504,11 @@ static void ufshcd_clk_scaling_suspend(struct ufs_hba *hba, bool suspend)
 
 static void ufshcd_err_handling_prepare(struct ufs_hba *hba)
 {
+	/*
+	 * A WLUN resume failure could potentially lead to the HBA being
+	 * runtime suspended, so take an extra reference on hba->dev.
+	 */
+	pm_runtime_get_sync(hba->dev);
 	ufshcd_rpm_get_sync(hba);
 	if (pm_runtime_status_suspended(&hba->ufs_device_wlun->sdev_gendev) ||
 	    hba->is_sys_suspended) {
@@ -6543,6 +6548,7 @@ static void ufshcd_err_handling_unprepare(struct ufs_hba *hba)
 	if (ufshcd_is_clkscaling_supported(hba))
 		ufshcd_clk_scaling_suspend(hba, false);
 	ufshcd_rpm_put(hba);
+	pm_runtime_put(hba->dev);
 }
 
 static inline bool ufshcd_err_handling_should_stop(struct ufs_hba *hba)
@@ -6557,28 +6563,42 @@ static inline bool ufshcd_err_handling_should_stop(struct ufs_hba *hba)
 #ifdef CONFIG_PM
 static void ufshcd_recover_pm_error(struct ufs_hba *hba)
 {
+	struct scsi_target *starget = hba->ufs_device_wlun->sdev_target;
 	struct Scsi_Host *shost = hba->host;
 	struct scsi_device *sdev;
 	struct request_queue *q;
-	int ret;
+	bool resume_sdev_queues = false;
 
 	hba->is_sys_suspended = false;
+
 	/*
-	 * Set RPM status of wlun device to RPM_ACTIVE,
-	 * this also clears its runtime error.
+	 * Ensure the parent's error status is cleared before proceeding
+	 * to the child, as the parent must be active to activate the child.
 	 */
-	ret = pm_runtime_set_active(&hba->ufs_device_wlun->sdev_gendev);
+	if (hba->dev->power.runtime_error) {
+		/* hba->dev has no functional parent thus simplily set RPM_ACTIVE */
+		pm_runtime_set_active(hba->dev);
+		resume_sdev_queues = true;
+	}
+
+	if (hba->ufs_device_wlun->sdev_gendev.power.runtime_error) {
+		/*
+		 * starget, parent of wlun, might be suspended if wlun resume failed.
+		 * Make sure parent is resumed before set child (wlun) active.
+		 */
+		pm_runtime_get_sync(&starget->dev);
+		pm_runtime_set_active(&hba->ufs_device_wlun->sdev_gendev);
+		pm_runtime_put_sync(&starget->dev);
+		resume_sdev_queues = true;
+	}
 
-	/* hba device might have a runtime error otherwise */
-	if (ret)
-		ret = pm_runtime_set_active(hba->dev);
 	/*
 	 * If wlun device had runtime error, we also need to resume those
 	 * consumer scsi devices in case any of them has failed to be
 	 * resumed due to supplier runtime resume failure. This is to unblock
 	 * blk_queue_enter in case there are bios waiting inside it.
 	 */
-	if (!ret) {
+	if (resume_sdev_queues) {
 		shost_for_each_device(sdev, shost) {
 			q = sdev->request_queue;
 			if (q->dev && (q->rpm_status == RPM_SUSPENDED ||

base-commit: c53a741a7fd4b8e9d07acf1861b5e4a188c6585a
-- 
2.51.2.1041.gc1ab5b90ca-goog