[PATCH] scsi: ufs: core: Keep clock-gating hold on failed W-LUN runtime resume

[Stanley Jhu]

1. __ufshcd_wl_suspend() takes one ufshcd_hold() reference and sets
   hba->clk_gating.is_suspended while the UFS device W-LUN enters
   RPM_SUSPENDED.
2. Since commit eef1d74bf88f ("PM: runtime: Only set runtime_error on
   suspend callback failures"), a failed runtime resume (for example
   START STOP UNIT completing with an error) leaves the W-LUN in
   RPM_SUSPENDED with power.runtime_error == 0, while
   __ufshcd_wl_resume() already clears hba->clk_gating.is_suspended and
   calls ufshcd_release().
3. The next W-LUN runtime resume runs __ufshcd_wl_resume() again without
   an intervening suspend and calls ufshcd_release() a second time,
   dropping a reference it does not own and underflowing
   hba->clk_gating.active_reqs on UFSHCD_CAP_CLK_GATING hosts.

Keep hba->clk_gating.is_suspended and the suspend hold across a failed
W-LUN runtime resume, so the hold stays paired with the W-LUN
RPM_SUSPENDED state and the next successful resume releases it.

Fixes: eef1d74bf88f ("PM: runtime: Only set runtime_error on suspend callback failures")
Cc: stable@xxxxxxxxxxxxxxx # v7.3+
Signed-off-by: Stanley Jhu <stanleyjhu@xxxxxxxxxx>
---
 drivers/ufs/core/ufshcd.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index cc75384c6502..9be370cea52a 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -10626,8 +10626,14 @@ static int __ufshcd_wl_resume(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 out:
 	if (ret)
 		ufshcd_update_evt_hist(hba, UFS_EVT_WL_RES_ERR, (u32)ret);
-	hba->clk_gating.is_suspended = false;
-	ufshcd_release(hba);
+	/*
+	 * A failed runtime resume leaves the W-LUN RPM_SUSPENDED, so keep
+	 * is_suspended and the suspend hold for the next resume.
+	 */
+	if (!ret || pm_op != UFS_RUNTIME_PM) {
+		hba->clk_gating.is_suspended = false;
+		ufshcd_release(hba);
+	}
 	hba->pm_op_in_progress = false;
 	return ret;
 }
-- 
2.56.0.313.g2479322e68-goog