[PATCH] staging: atomisp: reduce kernel stack usage

From: Arnd Bergmann
Date: Fri Feb 26 2021 - 09:10:19 EST

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From: Arnd Bergmann <arnd@xxxxxxxx>

The atomisp_set_fmt() function has multiple copies of the large
v4l2_format structure on its stack, resulting in a warning about
excessive stack usage in some rare randconfig builds.

drivers/staging/media/atomisp/pci/atomisp_cmd.c:5600:5: error: stack frame size of 1084 bytes in function 'atomisp_set_fmt' [-Werror,-Wframe-larger-than=]

Of this structure, only three members in the 'fmt.pix' member are
used, so simplify it by using the smaller v4l2_pix_format structure
directly. This reduces the stack usage to 612 bytes, and it could
be reduced further by only storing the three members that are used.

Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
.../staging/media/atomisp/pci/atomisp_cmd.c | 65 +++++++++----------
.../staging/media/atomisp/pci/atomisp_cmd.h | 2 +-
.../staging/media/atomisp/pci/atomisp_ioctl.c | 2 +-
3 files changed, 33 insertions(+), 36 deletions(-)

diff --git a/drivers/staging/media/atomisp/pci/atomisp_cmd.c b/drivers/staging/media/atomisp/pci/atomisp_cmd.c
index 592ea990d4ca..3192c0716eb9 100644
--- a/drivers/staging/media/atomisp/pci/atomisp_cmd.c
+++ b/drivers/staging/media/atomisp/pci/atomisp_cmd.c
@@ -4837,7 +4837,7 @@ static void __atomisp_init_stream_info(u16 stream_index,
}

/* This function looks up the closest available resolution. */
-int atomisp_try_fmt(struct video_device *vdev, struct v4l2_format *f,
+int atomisp_try_fmt(struct video_device *vdev, struct v4l2_pix_format *f,
bool *res_overflow)
{
struct atomisp_device *isp = video_get_drvdata(vdev);
@@ -4859,18 +4859,18 @@ int atomisp_try_fmt(struct video_device *vdev, struct v4l2_format *f,
return -EINVAL;

stream_index = atomisp_source_pad_to_stream_id(asd, source_pad);
- fmt = atomisp_get_format_bridge(f->fmt.pix.pixelformat);
+ fmt = atomisp_get_format_bridge(f->pixelformat);
if (!fmt) {
dev_err(isp->dev, "unsupported pixelformat!\n");
fmt = atomisp_output_fmts;
}

- if (f->fmt.pix.width <= 0 || f->fmt.pix.height <= 0)
+ if (f->width <= 0 || f->height <= 0)
return -EINVAL;

snr_mbus_fmt->code = fmt->mbus_code;
- snr_mbus_fmt->width = f->fmt.pix.width;
- snr_mbus_fmt->height = f->fmt.pix.height;
+ snr_mbus_fmt->width = f->width;
+ snr_mbus_fmt->height = f->height;

__atomisp_init_stream_info(stream_index, stream_info);

@@ -4892,7 +4892,7 @@ int atomisp_try_fmt(struct video_device *vdev, struct v4l2_format *f,
return -EINVAL;
}

- f->fmt.pix.pixelformat = fmt->pixelformat;
+ f->pixelformat = fmt->pixelformat;

/*
* If the format is jpeg or custom RAW, then the width and height will
@@ -4900,17 +4900,17 @@ int atomisp_try_fmt(struct video_device *vdev, struct v4l2_format *f,
* the below conditions. So just assign to what is being returned from
* the sensor driver.
*/
- if (f->fmt.pix.pixelformat == V4L2_PIX_FMT_JPEG ||
- f->fmt.pix.pixelformat == V4L2_PIX_FMT_CUSTOM_M10MO_RAW) {
- f->fmt.pix.width = snr_mbus_fmt->width;
- f->fmt.pix.height = snr_mbus_fmt->height;
+ if (f->pixelformat == V4L2_PIX_FMT_JPEG ||
+ f->pixelformat == V4L2_PIX_FMT_CUSTOM_M10MO_RAW) {
+ f->width = snr_mbus_fmt->width;
+ f->height = snr_mbus_fmt->height;
return 0;
}

- if (snr_mbus_fmt->width < f->fmt.pix.width
- && snr_mbus_fmt->height < f->fmt.pix.height) {
- f->fmt.pix.width = snr_mbus_fmt->width;
- f->fmt.pix.height = snr_mbus_fmt->height;
+ if (snr_mbus_fmt->width < f->width
+ && snr_mbus_fmt->height < f->height) {
+ f->width = snr_mbus_fmt->width;
+ f->height = snr_mbus_fmt->height;
/* Set the flag when resolution requested is
* beyond the max value supported by sensor
*/
@@ -4919,12 +4919,10 @@ int atomisp_try_fmt(struct video_device *vdev, struct v4l2_format *f,
}

/* app vs isp */
- f->fmt.pix.width = rounddown(
- clamp_t(u32, f->fmt.pix.width, ATOM_ISP_MIN_WIDTH,
- ATOM_ISP_MAX_WIDTH), ATOM_ISP_STEP_WIDTH);
- f->fmt.pix.height = rounddown(
- clamp_t(u32, f->fmt.pix.height, ATOM_ISP_MIN_HEIGHT,
- ATOM_ISP_MAX_HEIGHT), ATOM_ISP_STEP_HEIGHT);
+ f->width = rounddown(clamp_t(u32, f->width, ATOM_ISP_MIN_WIDTH,
+ ATOM_ISP_MAX_WIDTH), ATOM_ISP_STEP_WIDTH);
+ f->height = rounddown(clamp_t(u32, f->height, ATOM_ISP_MIN_HEIGHT,
+ ATOM_ISP_MAX_HEIGHT), ATOM_ISP_STEP_HEIGHT);

return 0;
}
@@ -5481,7 +5479,7 @@ static void atomisp_get_dis_envelop(struct atomisp_sub_device *asd,
}

static void atomisp_check_copy_mode(struct atomisp_sub_device *asd,
- int source_pad, struct v4l2_format *f)
+ int source_pad, struct v4l2_pix_format *f)
{
#if defined(ISP2401_NEW_INPUT_SYSTEM)
struct v4l2_mbus_framefmt *sink, *src;
@@ -5492,8 +5490,8 @@ static void atomisp_check_copy_mode(struct atomisp_sub_device *asd,
V4L2_SUBDEV_FORMAT_ACTIVE, source_pad);

if ((sink->code == src->code &&
- sink->width == f->fmt.pix.width &&
- sink->height == f->fmt.pix.height) ||
+ sink->width == f->width &&
+ sink->height == f->height) ||
((asd->isp->inputs[asd->input_curr].type == SOC_CAMERA) &&
(asd->isp->inputs[asd->input_curr].camera_caps->
sensor[asd->sensor_curr].stream_num > 1)))
@@ -5507,7 +5505,7 @@ static void atomisp_check_copy_mode(struct atomisp_sub_device *asd,
}

static int atomisp_set_fmt_to_snr(struct video_device *vdev,
- struct v4l2_format *f, unsigned int pixelformat,
+ struct v4l2_pix_format *f, unsigned int pixelformat,
unsigned int padding_w, unsigned int padding_h,
unsigned int dvs_env_w, unsigned int dvs_env_h)
{
@@ -5535,7 +5533,7 @@ static int atomisp_set_fmt_to_snr(struct video_device *vdev,
if (!format)
return -EINVAL;

- v4l2_fill_mbus_format(ffmt, &f->fmt.pix, format->mbus_code);
+ v4l2_fill_mbus_format(ffmt, f, format->mbus_code);
ffmt->height += padding_h + dvs_env_h;
ffmt->width += padding_w + dvs_env_w;

@@ -5605,8 +5603,8 @@ int atomisp_set_fmt(struct video_device *vdev, struct v4l2_format *f)
const struct atomisp_format_bridge *format_bridge;
const struct atomisp_format_bridge *snr_format_bridge;
struct ia_css_frame_info output_info, raw_output_info;
- struct v4l2_format snr_fmt = *f;
- struct v4l2_format backup_fmt = *f, s_fmt = *f;
+ struct v4l2_pix_format snr_fmt = f->fmt.pix;
+ struct v4l2_pix_format backup_fmt = snr_fmt, s_fmt;
unsigned int dvs_env_w = 0, dvs_env_h = 0;
unsigned int padding_w = pad_w, padding_h = pad_h;
bool res_overflow = false, crop_needs_override = false;
@@ -5780,11 +5778,10 @@ int atomisp_set_fmt(struct video_device *vdev, struct v4l2_format *f)
dev_warn(isp->dev, "Try format failed with error %d\n", ret);
return ret;
}
- f->fmt.pix.width = snr_fmt.fmt.pix.width;
- f->fmt.pix.height = snr_fmt.fmt.pix.height;
+ f->fmt.pix.width = snr_fmt.width;
+ f->fmt.pix.height = snr_fmt.height;

- snr_format_bridge =
- atomisp_get_format_bridge(snr_fmt.fmt.pix.pixelformat);
+ snr_format_bridge = atomisp_get_format_bridge(snr_fmt.pixelformat);
if (!snr_format_bridge) {
dev_warn(isp->dev, "Can't find bridge format\n");
return -EINVAL;
@@ -5865,11 +5862,11 @@ int atomisp_set_fmt(struct video_device *vdev, struct v4l2_format *f)
* and height while set_mbus_fmt() so actual resolutions are
* being used in while set media bus format.
*/
- s_fmt = *f;
+ s_fmt = f->fmt.pix;
if (f->fmt.pix.pixelformat == V4L2_PIX_FMT_JPEG ||
f->fmt.pix.pixelformat == V4L2_PIX_FMT_CUSTOM_M10MO_RAW) {
- s_fmt.fmt.pix.width = backup_fmt.fmt.pix.width;
- s_fmt.fmt.pix.height = backup_fmt.fmt.pix.height;
+ s_fmt.width = backup_fmt.width;
+ s_fmt.height = backup_fmt.height;
}
ret = atomisp_set_fmt_to_snr(vdev, &s_fmt,
f->fmt.pix.pixelformat, padding_w,
diff --git a/drivers/staging/media/atomisp/pci/atomisp_cmd.h b/drivers/staging/media/atomisp/pci/atomisp_cmd.h
index 1c0d464c2ac1..412baeb91944 100644
--- a/drivers/staging/media/atomisp/pci/atomisp_cmd.h
+++ b/drivers/staging/media/atomisp/pci/atomisp_cmd.h
@@ -333,7 +333,7 @@ int atomisp_get_sensor_mode_data(struct atomisp_sub_device *asd,
int atomisp_get_fmt(struct video_device *vdev, struct v4l2_format *f);

/* This function looks up the closest available resolution. */
-int atomisp_try_fmt(struct video_device *vdev, struct v4l2_format *f,
+int atomisp_try_fmt(struct video_device *vdev, struct v4l2_pix_format *f,
bool *res_overflow);

int atomisp_set_fmt(struct video_device *vdev, struct v4l2_format *f);
diff --git a/drivers/staging/media/atomisp/pci/atomisp_ioctl.c b/drivers/staging/media/atomisp/pci/atomisp_ioctl.c
index 2ae50decfc8b..c6adffebe24a 100644
--- a/drivers/staging/media/atomisp/pci/atomisp_ioctl.c
+++ b/drivers/staging/media/atomisp/pci/atomisp_ioctl.c
@@ -843,7 +843,7 @@ static int atomisp_try_fmt_cap(struct file *file, void *fh,
int ret;

rt_mutex_lock(&isp->mutex);
- ret = atomisp_try_fmt(vdev, f, NULL);
+ ret = atomisp_try_fmt(vdev, &f->fmt.pix, NULL);
rt_mutex_unlock(&isp->mutex);
return ret;
}
--
2.29.2

Next message: Arnd Bergmann: "[PATCH] media: mtk: fix mtk-smi dependency"
Previous message: Dan Carpenter: "Re: [PATCH] staging: rtl8192e: Fix possible buffer overflow in _rtl92e_wx_set_scan"
Next in thread: Andy Shevchenko: "Re: [PATCH] staging: atomisp: reduce kernel stack usage"
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