On Tue Jun 30 12:52:57 2026 +0200, Yousef Alhouseen wrote:
> The byte-alignment paths can call CODE_ADD() with a zero bit
> length. The macro then shifts an int by name.b, which can be 32
> after the preceding bit was flushed.
>
> vti_bitlen() can likewise shift a signed int into its sign bit while
> searching for the bit length, and the package mask construction can
> shift by the full type width.
>
> Make zero-length additions a no-op, derive the bit length with fls(),
> and build the mask with GENMASK().
>
> Signed-off-by: Yousef Alhouseen <[email protected]>
> Signed-off-by: Hans Verkuil <[email protected]>
Patch committed.
Thanks,
Hans Verkuil
drivers/media/usb/go7007/go7007-fw.c | 28 +++++++++++++++-------------
1 file changed, 15 insertions(+), 13 deletions(-)
---
diff --git a/drivers/media/usb/go7007/go7007-fw.c
b/drivers/media/usb/go7007/go7007-fw.c
index 86ce593e0c54..8cf959c20e30 100644
--- a/drivers/media/usb/go7007/go7007-fw.c
+++ b/drivers/media/usb/go7007/go7007-fw.c
@@ -13,6 +13,7 @@
*/
#include <linux/module.h>
+#include <linux/bitops.h>
#include <linux/time.h>
#include <linux/mm.h>
#include <linux/device.h>
@@ -58,14 +59,16 @@ struct code_gen {
#define CODE_GEN(name, dest) struct code_gen name = { dest, 0, 32, 0 }
#define CODE_ADD(name, val, length) do { \
- name.b -= (length); \
- name.a |= (val) << name.b; \
- while (name.b <= 24) { \
- *name.p = name.a >> 24; \
- ++name.p; \
- name.a <<= 8; \
- name.b += 8; \
- name.len += 8; \
+ if (length) { \
+ name.b -= (length); \
+ name.a |= (val) << name.b; \
+ while (name.b <= 24) { \
+ *name.p = name.a >> 24; \
+ ++name.p; \
+ name.a <<= 8; \
+ name.b += 8; \
+ name.len += 8; \
+ } \
} \
} while (0)
@@ -707,11 +710,10 @@ done:
static int vti_bitlen(struct go7007 *go)
{
- unsigned int i, max_time_incr = go->sensor_framerate / go->fps_scale;
+ unsigned int max_time_incr = go->sensor_framerate / go->fps_scale;
+ int bitlen = fls(max_time_incr);
- for (i = 31; (max_time_incr & ((1 << i) - 1)) == max_time_incr; --i)
- ;
- return i + 1;
+ return bitlen ?: 1;
}
static int mpeg4_frame_header(struct go7007 *go, unsigned char *buf,
@@ -1209,7 +1211,7 @@ static int seqhead_to_package(struct go7007 *go, __le16
*code, int space,
0xbf08, fps,
0xbf09, 0,
0xbff2, vop_time_increment_bitlength,
- 0xbff3, (1 << vop_time_increment_bitlength) - 1,
+ 0xbff3, GENMASK(vop_time_increment_bitlength - 1, 0),
0xbfe6, 0,
0xbfe7, (fps / 1000) << 8,
0, 0,
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