Re: [PATCH 1/2] bdisp: Fix a possible sleep-in-atomic bug in bdisp_hw_reset

From: Jia-Ju Bai
Date: Sat Dec 16 2017 - 06:54:12 EST


On 2017/12/15 22:51, Fabien DESSENNE wrote:

On 12/12/17 14:47, Jia-Ju Bai wrote:
The driver may sleep under a spinlock.
The function call path is:
bdisp_device_run (acquire the spinlock)
msleep --> may sleep

To fix it, msleep is replaced with mdelay.
May I suggest you to use readl_poll_timeout_atomic (instead of the whole
"for" block): this fixes the problem and simplifies the code?

Okay, I have submitted a patch according to your advice.
You can have a look :)

Jia-Ju Bai

This bug is found by my static analysis tool(DSAC) and checked by my code review.

Signed-off-by: Jia-Ju Bai <baijiaju1990@xxxxxxxxx>
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 b7892f3..4b62ceb 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)
- msleep(POLL_RST_DELAY_MS);
+ mdelay(POLL_RST_DELAY_MS);
if (i == POLL_RST_MAX)
dev_err(bdisp->dev, "Reset timeout\n");