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* [PATCH v1] scsi: ufs: Fix possible infinite loop in ufshcd_hold
@ 2020-07-28 14:10 Stanley Chu
  0 siblings, 0 replies; only message in thread
From: Stanley Chu @ 2020-07-28 14:10 UTC (permalink / raw)
  To: linux-scsi, martin.petersen, avri.altman, alim.akhtar, jejb, bvanassche
  Cc: beanhuo, asutoshd, cang, matthias.bgg, linux-mediatek,
	linux-arm-kernel, linux-kernel,,,
	chun-hung.wu, andy.teng, chaotian.jing, cc.chou, Stanley Chu

In ufshcd_suspend(), after clk-gating is suspended and link is set
as Hibern8 state, ufshcd_hold() is still possibly invoked before
ufshcd_suspend() returns. For example, MediaTek's suspend vops may
issue UIC commands which would call ufshcd_hold() during the command
issuing flow.

Now if UFSHCD_CAP_HIBERN8_WITH_CLK_GATING capability is enabled,
then ufshcd_hold() may enter infinite loops because there is no
clk-ungating work is scheduled or pending. In this case, ufshcd_hold()
shall just bypass, and keep the link as Hibern8 state.

Signed-off-by: Stanley Chu <>
Signed-off-by: Andy Teng <>
 drivers/scsi/ufs/ufshcd.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 577cc0d7487f..267b02e1afd6 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1592,7 +1592,11 @@ int ufshcd_hold(struct ufs_hba *hba, bool async)
 			spin_unlock_irqrestore(hba->host->host_lock, flags);
-			flush_work(&hba->clk_gating.ungate_work);
+			rc = flush_work(&hba->clk_gating.ungate_work);
+			if (hba->clk_gating.is_suspended && !rc) {
+				rc = 0;
+				goto out;
+			}
 			spin_lock_irqsave(hba->host->host_lock, flags);
 			goto start;

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2020-07-28 14:10 [PATCH v1] scsi: ufs: Fix possible infinite loop in ufshcd_hold Stanley Chu

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