From: Jia-Ju Bai <baijiaju1990@gmail.com>
Date: Thu, 19 Dec 2019 10:34:01 +0000 (+0100)
Subject: media: sti: bdisp: fix a possible sleep-in-atomic-context bug in bdisp_device_run()
X-Git-Tag: v5.15~4579^2~43
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=bb6d42061a05d71dd73f620582d9e09c8fbf7f5b;p=platform%2Fkernel%2Flinux-starfive.git

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 udelay().

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

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Reviewed-by: Fabien Dessenne <fabien.dessenne@st.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
---

diff --git a/drivers/media/platform/sti/bdisp/bdisp-hw.c b/drivers/media/platform/sti/bdisp/bdisp-hw.c
index 4372abb..a74e9fd 100644
--- a/drivers/media/platform/sti/bdisp/bdisp-hw.c
+++ b/drivers/media/platform/sti/bdisp/bdisp-hw.c
@@ -14,8 +14,8 @@
 #define MAX_SRC_WIDTH           2048
 
 /* Reset & boot poll config */
-#define POLL_RST_MAX            50
-#define POLL_RST_DELAY_MS       20
+#define POLL_RST_MAX            500
+#define POLL_RST_DELAY_MS       2
 
 enum bdisp_target_plan {
 	BDISP_RGB,
@@ -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);
+		udelay(POLL_RST_DELAY_MS * 1000);
 	}
 	if (i == POLL_RST_MAX)
 		dev_err(bdisp->dev, "Reset timeout\n");