[PATCH v1 3/3] media: cedrus: Fix endless loop in cedrus_h265_skip_bits()

[Nicolas Dufresne]

From: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx>

The busy status bit may never de-assert if number of programmed skip
bits is incorrect, resulting in a kernel hang because the bit is polled
endlessly in the code. Fix it by adding timeout for the bit-polling.
This problem is reproducible by setting the data_bit_offset field of
the HEVC slice params to a wrong value by userspace.

Cc: stable@xxxxxxxxxxxxxxx
Reported-by: Nicolas Dufresne <nicolas.dufresne@xxxxxxxxxxxxx>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx>
Signed-off-by: Nicolas Dufresne <nicolas.dufresne@xxxxxxxxxxxxx>
---
 drivers/staging/media/sunxi/cedrus/cedrus_h265.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_h265.c b/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
index f703c585d91c5..f0bc118021b0a 100644
--- a/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
+++ b/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
@@ -227,6 +227,7 @@ static void cedrus_h265_pred_weight_write(struct cedrus_dev *dev,
 static void cedrus_h265_skip_bits(struct cedrus_dev *dev, int num)
 {
 	int count = 0;
+	u32 reg;
 
 	while (count < num) {
 		int tmp = min(num - count, 32);
@@ -234,8 +235,9 @@ static void cedrus_h265_skip_bits(struct cedrus_dev *dev, int num)
 		cedrus_write(dev, VE_DEC_H265_TRIGGER,
 			     VE_DEC_H265_TRIGGER_FLUSH_BITS |
 			     VE_DEC_H265_TRIGGER_TYPE_N_BITS(tmp));
-		while (cedrus_read(dev, VE_DEC_H265_STATUS) & VE_DEC_H265_STATUS_VLD_BUSY)
-			udelay(1);
+
+		if (cedrus_wait_for(dev, VE_DEC_H265_STATUS, VE_DEC_H265_STATUS_VLD_BUSY))
+			dev_err_ratelimited(dev->dev, "timed out waiting to skip bits\n");
 
 		count += tmp;
 	}
-- 
2.37.2