From: Bill Wendling <morbo@xxxxxxxxxx>
Work for __counted_by on generic pointers in structures (not just
flexible array members) has started landing in Clang 19 (current tip of
tree). During the development of this feature, a restriction was added
to __counted_by to prevent the flexible array member's element type from
including a flexible array member itself such as:
struct foo {
int count;
char buf[];
};
struct bar {
int count;
struct foo data[] __counted_by(count);
};
because the size of data cannot be calculated with the standard array
size formula:
sizeof(struct foo) * count
This restriction was downgraded to a warning but due to CONFIG_WERROR,
it can still break the build. The application of __counted_by on the
states member of 'struct _StateArray' triggers this restriction,
resulting in:
drivers/gpu/drm/radeon/pptable.h:442:5: error: 'counted_by' should not be applied to an array with element of unknown size because 'ATOM_PPLIB_STATE_V2' (aka 'struct _ATOM_PPLIB_STATE_V2') is a struct type with a flexible array member. This will be an error in a future compiler version [-Werror,-Wbounds-safety-counted-by-elt-type-unknown-size]
442 | ATOM_PPLIB_STATE_V2 states[] __counted_by(ucNumEntries);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.
Remove this use of __counted_by to fix the warning/error. However,
rather than remove it altogether, leave it commented, as it may be
possible to support this in future compiler releases.
Cc: stable@xxxxxxxxxxxxxxx
Closes: https://github.com/ClangBuiltLinux/linux/issues/2028
Fixes: efade6fe50e7 ("drm/radeon: silence UBSAN warning (v3)")
Signed-off-by: Bill Wendling <morbo@xxxxxxxxxx>
Co-developed-by: Nathan Chancellor <nathan@xxxxxxxxxx>
Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx>
---
drivers/gpu/drm/radeon/pptable.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/radeon/pptable.h b/drivers/gpu/drm/radeon/pptable.h
index b7f22597ee95..969a8fb0ee9e 100644
--- a/drivers/gpu/drm/radeon/pptable.h
+++ b/drivers/gpu/drm/radeon/pptable.h
@@ -439,7 +439,7 @@ typedef struct _StateArray{
//how many states we have
UCHAR ucNumEntries;
- ATOM_PPLIB_STATE_V2 states[] __counted_by(ucNumEntries);
+ ATOM_PPLIB_STATE_V2 states[] /* __counted_by(ucNumEntries) */;
}StateArray;
---
base-commit: e64e8f7c178e5228e0b2dbb504b9dc75953a319f
change-id: 20240529-drop-counted-by-radeon-states-state-array-01936ded4c18
Best regards,
--
Nathan Chancellor <nathan@xxxxxxxxxx>
