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author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-03-05 04:58:42 -0600 |
---|---|---|
committer | Thomas Hellstrom <thellstrom@vmware.com> | 2020-03-16 10:42:01 +0100 |
commit | 6b656755428dc0c96d21d7af697dc2a10c7ff175 (patch) | |
tree | 24a5dd68d983da442e6fdfba96b59fd890469b08 /drivers/gpu/drm/vmwgfx | |
parent | 2bdb7380fe128481f30b8db7558cef248ca27434 (diff) | |
download | linux-6b656755428dc0c96d21d7af697dc2a10c7ff175.tar.bz2 |
drm/vmwgfx: Replace zero-length array with flexible-array member
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]
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 <gustavo@embeddedor.com>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Diffstat (limited to 'drivers/gpu/drm/vmwgfx')
-rw-r--r-- | drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c | 2 | ||||
-rw-r--r-- | drivers/gpu/drm/vmwgfx/vmwgfx_surface.c | 2 |
2 files changed, 2 insertions, 2 deletions
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c b/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c index f07aa857587c..60cfbfadd3f2 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c @@ -69,7 +69,7 @@ struct vmw_bo_dirty { unsigned int ref_count; unsigned long bitmap_size; size_t size; - unsigned long bitmap[0]; + unsigned long bitmap[]; }; /** diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c index 3ce630aa4fde..ec893cd17b50 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c @@ -79,7 +79,7 @@ struct vmw_surface_dirty { struct svga3dsurface_cache cache; size_t size; u32 num_subres; - SVGA3dBox boxes[0]; + SVGA3dBox boxes[]; }; static void vmw_user_surface_free(struct vmw_resource *res); |