[PATCH v6 8/9] media: Avoid parsing quantization and huffman tables

From: Mirela Rabulea (OSS)
Date: Tue Dec 15 2020 - 06:22:30 EST


From: Mirela Rabulea <mirela.rabulea@xxxxxxx>

These are optional in struct v4l2_jpeg_header, so skip DHT/DQT segment
parsing if huffman_tables/quantization_tables were not requested by user,
to save time.
However, do count them (num_dht/num_dqt).

Signed-off-by: Mirela Rabulea <mirela.rabulea@xxxxxxx>
---
Changes in v6:
Call jpeg_skip_segment() instead of jpeg_parse_quantization_table()/jpeg_parse_huffman_tables(),
when quantization/huffman tables are not requested by user.
Remove the NULL pointer check in the lower-level function.
Thanks Philipp & Hans for feedback

drivers/media/v4l2-core/v4l2-jpeg.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/drivers/media/v4l2-core/v4l2-jpeg.c b/drivers/media/v4l2-core/v4l2-jpeg.c
index dc9def4c2648..f3d03d39defb 100644
--- a/drivers/media/v4l2-core/v4l2-jpeg.c
+++ b/drivers/media/v4l2-core/v4l2-jpeg.c
@@ -537,6 +537,10 @@ int v4l2_jpeg_parse_header(void *buf, size_t len, struct v4l2_jpeg_header *out)
&out->dht[out->num_dht++ % 4]);
if (ret < 0)
return ret;
+ if (!out->huffman_tables) {
+ ret = jpeg_skip_segment(&stream);
+ break;
+ }
ret = jpeg_parse_huffman_tables(&stream,
out->huffman_tables);
break;
@@ -545,6 +549,10 @@ int v4l2_jpeg_parse_header(void *buf, size_t len, struct v4l2_jpeg_header *out)
&out->dqt[out->num_dqt++ % 4]);
if (ret < 0)
return ret;
+ if (!out->quantization_tables) {
+ ret = jpeg_skip_segment(&stream);
+ break;
+ }
ret = jpeg_parse_quantization_tables(&stream,
out->frame.precision,
out->quantization_tables);
--
2.17.1