linux-kernel - [PATCH] media: sti: bdisp: fix a possible sleep-in-atomic-context bug in bdisp_device

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Message-Id: <20191218140537.12193-1-baijiaju1990@gmail.com>
Date:   Wed, 18 Dec 2019 22:05:37 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     fabien.dessenne@...com, mchehab@...nel.org
Cc:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jia-Ju Bai <baijiaju1990@...il.com>
Subject: [PATCH] media: sti: bdisp: fix a possible sleep-in-atomic-context bug in bdisp_device_run()

The driver may sleep while holding a spinlock.
The function call path (from bottom to top) in Linux 4.19 is:

drivers/media/platform/sti/bdisp/bdisp-hw.c, 385: 
	msleep in bdisp_hw_reset
drivers/media/platform/sti/bdisp/bdisp-v4l2.c, 341: 
	bdisp_hw_reset in bdisp_device_run
drivers/media/platform/sti/bdisp/bdisp-v4l2.c, 317:
	_raw_spin_lock_irqsave in bdisp_device_run

To fix this bug, msleep() is replaced with mdelay().

This bug is found by a static analysis tool STCheck written by myself.

Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
---
 drivers/media/platform/sti/bdisp/bdisp-hw.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/platform/sti/bdisp/bdisp-hw.c b/drivers/media/platform/sti/bdisp/bdisp-hw.c
index 4372abbb5950..1a56348805a2 100644
--- a/drivers/media/platform/sti/bdisp/bdisp-hw.c
+++ b/drivers/media/platform/sti/bdisp/bdisp-hw.c
@@ -382,7 +382,7 @@ int bdisp_hw_reset(struct bdisp_dev *bdisp)
 	for (i = 0; i < POLL_RST_MAX; i++) {
 		if (readl(bdisp->regs + BLT_STA1) & BLT_STA1_IDLE)
 			break;
-		msleep(POLL_RST_DELAY_MS);
+		mdelay(POLL_RST_DELAY_MS);
 	}
 	if (i == POLL_RST_MAX)
 		dev_err(bdisp->dev, "Reset timeout\n");
-- 
2.17.1