[PATCH 4.4 37/62] scsi: ufs: Fix possible infinite loop in ufshcd_hold

From: Greg Kroah-Hartman
Date: Tue Sep 01 2020 - 13:20:47 EST


From: Stanley Chu <stanley.chu@xxxxxxxxxxxx>

[ Upstream commit 93b6c5db06028a3b55122bbb74d0715dd8ca4ae0 ]

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 scheduled or pending. In this case, ufshcd_hold()
shall just bypass, and keep the link as Hibern8 state.

Link: https://lore.kernel.org/r/20200809050734.18740-1-stanley.chu@xxxxxxxxxxxx
Reviewed-by: Avri Altman <avri.altman@xxxxxxx>
Co-developed-by: Andy Teng <andy.teng@xxxxxxxxxxxx>
Signed-off-by: Andy Teng <andy.teng@xxxxxxxxxxxx>
Signed-off-by: Stanley Chu <stanley.chu@xxxxxxxxxxxx>
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/scsi/ufs/ufshcd.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index d15cd7a02f9b4..d7a0a64f64536 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -575,6 +575,7 @@ unblock_reqs:
int ufshcd_hold(struct ufs_hba *hba, bool async)
{
int rc = 0;
+ bool flush_result;
unsigned long flags;

if (!ufshcd_is_clkgating_allowed(hba))
@@ -601,7 +602,9 @@ start:
break;
}
spin_unlock_irqrestore(hba->host->host_lock, flags);
- flush_work(&hba->clk_gating.ungate_work);
+ flush_result = flush_work(&hba->clk_gating.ungate_work);
+ if (hba->clk_gating.is_suspended && !flush_result)
+ goto out;
spin_lock_irqsave(hba->host->host_lock, flags);
goto start;
}
--
2.25.1