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author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-03-05 04:57:07 -0600 |
---|---|---|
committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2020-03-06 11:50:17 +0100 |
commit | 5b2adbddf25c3543b265c0b8834a4580b971f71e (patch) | |
tree | a4bd7c1a85a74b2e1986572d8701b993999b5494 | |
parent | 1895a4fc3fad488038c4cdb4e417361649a61351 (diff) | |
download | linux-5b2adbddf25c3543b265c0b8834a4580b971f71e.tar.bz2 |
drm/vc4/vc4_drv.h: 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>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20200305105707.GA19261@embeddedor
-rw-r--r-- | drivers/gpu/drm/vc4/vc4_drv.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h index 26d1d5886352..139d25a8328e 100644 --- a/drivers/gpu/drm/vc4/vc4_drv.h +++ b/drivers/gpu/drm/vc4/vc4_drv.h @@ -65,7 +65,7 @@ struct vc4_perfmon { * Note that counter values can't be reset, but you can fake a reset by * destroying the perfmon and creating a new one. */ - u64 counters[0]; + u64 counters[]; }; struct vc4_dev { |