Fix the following compiler warning about excessive stack usage:
drivers/gpu/drm/radeon/radeon_cs.c:669:5: warning: stack frame size (1200)
exceeds limit (1024) in 'radeon_cs_ioctl' [-Wframe-larger-than]
The warning is caused by a large objects like `struct radeon_cs_parser`
being allocated on the stack. This patch changes the parser to be
heap-allocated via `kzalloc()`, thus reducing stack pressure.
It uses the __free() attribute to ensure automatic
cleanup on return.
This change should not affect functionality, as all usage of the
`parser` remains intact and is now accessed via a pointer.
Signed-off-by: Abinash Singh <abinashsinghlalo...@gmail.com>
---
the radeon_cs_ioctl() consumes around 1200 bytes on stack.
It was confirmed using -fstack-usage
....................................
divers/gpu/drm/radeon/radeon_cs.c:669:radeon_cs_ioctl 1200 static
drivers/gpu/drm/radeon/radeon_cs.c:416:radeon_cs_parser_fini 56 static
...............................................
After applying this patch the stack size effectivly reduces to 656 bytes
...............................................
drivers/gpu/drm/radeon/radeon_cs.c:669:radeon_cs_ioctl 656 static
drivers/gpu/drm/radeon/radeon_cs.c:416:radeon_cs_parser_fini 56 static
.....................................................
This will eliminate the build warning .But will this dynamic allocation with
kzalloc()
affect performance as compared to stack allocation + memset . Or will this way
we will
suffer greater penalty ?
drivers/gpu/drm/radeon/radeon_cs.c | 34 ++++++++++++++++--------------
1 file changed, 18 insertions(+), 16 deletions(-)
diff --git a/drivers/gpu/drm/radeon/radeon_cs.c
b/drivers/gpu/drm/radeon/radeon_cs.c
index b8e6202f1d5b..ca7fad842db7 100644
--- a/drivers/gpu/drm/radeon/radeon_cs.c
+++ b/drivers/gpu/drm/radeon/radeon_cs.c
@@ -669,9 +669,12 @@ static int radeon_cs_ib_fill(struct radeon_device *rdev,
struct radeon_cs_parser
int radeon_cs_ioctl(struct drm_device *dev, void *data, struct drm_file *filp)
{
struct radeon_device *rdev = dev->dev_private;
- struct radeon_cs_parser parser;
+ struct radeon_cs_parser *parser __free(kfree) = NULL;
int r;
-
+
+ parser = kzalloc(sizeof(*parser), GFP_KERNEL);
+ if (!parser)
+ return -ENOMEM;
down_read(&rdev->exclusive_lock);
if (!rdev->accel_working) {
up_read(&rdev->exclusive_lock);
@@ -685,46 +688,45 @@ int radeon_cs_ioctl(struct drm_device *dev, void *data,
struct drm_file *filp)
return r;
}
/* initialize parser */
- memset(&parser, 0, sizeof(struct radeon_cs_parser));
- parser.filp = filp;
- parser.rdev = rdev;
- parser.dev = rdev->dev;
- parser.family = rdev->family;
- r = radeon_cs_parser_init(&parser, data);
+ parser->filp = filp;
+ parser->rdev = rdev;
+ parser->dev = rdev->dev;
+ parser->family = rdev->family;
+ r = radeon_cs_parser_init(parser, data);
if (r) {
DRM_ERROR("Failed to initialize parser !\n");
- radeon_cs_parser_fini(&parser, r);
+ radeon_cs_parser_fini(parser, r);
up_read(&rdev->exclusive_lock);
r = radeon_cs_handle_lockup(rdev, r);
return r;
}
- r = radeon_cs_ib_fill(rdev, &parser);
+ r = radeon_cs_ib_fill(rdev, parser);
if (!r) {
- r = radeon_cs_parser_relocs(&parser);
+ r = radeon_cs_parser_relocs(parser);
if (r && r != -ERESTARTSYS)
DRM_ERROR("Failed to parse relocation %d!\n", r);
}
if (r) {
- radeon_cs_parser_fini(&parser, r);
+ radeon_cs_parser_fini(parser, r);
up_read(&rdev->exclusive_lock);
r = radeon_cs_handle_lockup(rdev, r);
return r;
}
- trace_radeon_cs(&parser);
+ trace_radeon_cs(parser);
- r = radeon_cs_ib_chunk(rdev, &parser);
+ r = radeon_cs_ib_chunk(rdev, parser);
if (r) {
goto out;
}
- r = radeon_cs_ib_vm_chunk(rdev, &parser);
+ r = radeon_cs_ib_vm_chunk(rdev, parser);
if (r) {
goto out;
}
out:
- radeon_cs_parser_fini(&parser, r);
+ radeon_cs_parser_fini(parser, r);
up_read(&rdev->exclusive_lock);
r = radeon_cs_handle_lockup(rdev, r);
return r;
--q
2.43.0
