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| author | Gustavo A. R. Silva <gustavoars@kernel.org> | 2020-05-07 13:54:08 -0500 |
|---|---|---|
| committer | Chris Wilson <chris@chris-wilson.co.uk> | 2020-05-09 12:59:23 +0100 |
| commit | f1e79c7e183c8e35def44b07ff7ac221fa87bf04 (patch) | |
| tree | 76af124c6dfad4bef150887d5618156f5eeec327 /drivers/gpu/drm/i915/i915_gpu_error.h | |
| parent | 16dc224f1c0ff8d242ef41c40d4da0264d351daa (diff) | |
| download | linux-f1e79c7e183c8e35def44b07ff7ac221fa87bf04.tar.bz2 | |
drm/i915: Replace zero-length array with flexible-array
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:
struct foo {
int stuff;
struct boo array[];
};
By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.
Also, notice that, dynamic memory allocations won't be affected by
this change:
"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]
sizeof(flexible-array-member) triggers a warning because flexible array
members have incomplete type[1]. There are some instances of code in
which the sizeof operator is being incorrectly/erroneously applied to
zero-length arrays and the result is zero. Such instances may be hiding
some bugs. So, this work (flexible-array member conversions) will also
help to get completely rid of those sorts of issues.
This issue was found with the help of Coccinelle.
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20200507185408.GA14561@embeddedor
Diffstat (limited to 'drivers/gpu/drm/i915/i915_gpu_error.h')
| -rw-r--r-- | drivers/gpu/drm/i915/i915_gpu_error.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/gpu/drm/i915/i915_gpu_error.h b/drivers/gpu/drm/i915/i915_gpu_error.h index fa2d82a6de04..76b80fbfb7e9 100644 --- a/drivers/gpu/drm/i915/i915_gpu_error.h +++ b/drivers/gpu/drm/i915/i915_gpu_error.h @@ -42,7 +42,7 @@ struct i915_vma_coredump { int num_pages; int page_count; int unused; - u32 *pages[0]; + u32 *pages[]; }; struct i915_request_coredump { |