linux-kernel - [PATCH v1] scsi: ufs: Fix possible infinite loop in ufshcd

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Message-ID: <20200728141055.22160-1-stanley.chu@mediatek.com>
Date:   Tue, 28 Jul 2020 22:10:55 +0800
From:   Stanley Chu <stanley.chu@...iatek.com>
To:     <linux-scsi@...r.kernel.org>, <martin.petersen@...cle.com>,
        <avri.altman@....com>, <alim.akhtar@...sung.com>,
        <jejb@...ux.ibm.com>, <bvanassche@....org>
CC:     <beanhuo@...ron.com>, <asutoshd@...eaurora.org>,
        <cang@...eaurora.org>, <matthias.bgg@...il.com>,
        <linux-mediatek@...ts.infradead.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <kuohong.wang@...iatek.com>,
        <peter.wang@...iatek.com>, <chun-hung.wu@...iatek.com>,
        <andy.teng@...iatek.com>, <chaotian.jing@...iatek.com>,
        <cc.chou@...iatek.com>, Stanley Chu <stanley.chu@...iatek.com>
Subject: [PATCH v1] scsi: ufs: Fix possible infinite loop in ufshcd_hold

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 <stanley.chu@...iatek.com>
Signed-off-by: Andy Teng <andy.teng@...iatek.com>
---
 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)
 				break;
 			}
 			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;
 		}
-- 
2.18.0