From: Jia-Ju Bai <baijiaju1990@gmail.com>
To: fabien.dessenne@st.com, mchehab@kernel.org
Cc: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
Jia-Ju Bai <baijiaju1990@gmail.com>
Subject: [PATCH v2] media: sti: bdisp: fix a possible sleep-in-atomic-context bug in bdisp_device_run()
Date: Thu, 19 Dec 2019 18:34:01 +0800 [thread overview]
Message-ID: <20191219103401.13630-1-baijiaju1990@gmail.com> (raw)
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>
---
v2:
* Use udelay() instead of mdelay().
Thank Fabien for good advice.
---
drivers/media/platform/sti/bdisp/bdisp-hw.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/media/platform/sti/bdisp/bdisp-hw.c b/drivers/media/platform/sti/bdisp/bdisp-hw.c
index 4372abbb5950..a74e9fd65238 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");
--
2.17.1
next reply other threads:[~2019-12-19 10:34 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-19 10:34 Jia-Ju Bai [this message]
2019-12-19 11:14 ` Fabien DESSENNE
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