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| author |   Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-04-06 20:11:52 -0700 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2020-04-07 10:43:44 -0700 |
| commit | fba4168edecdd2781bcd83cb131977ec1157f87c (patch) | |
| tree | e19148dba584f3e3fbf1cd697b793d568bb56746 /kernel | |
| parent | kernel/kmod.c: fix a typo "assuems" -> "assumes" (diff) | |
| download | linux-dev-fba4168edecdd2781bcd83cb131977ec1157f87c.tar.xz linux-dev-fba4168edecdd2781bcd83cb131977ec1157f87c.zip | |
gcov: gcc_4_7: 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: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Link: http://lkml.kernel.org/r/20200213152241.GA877@embeddedor
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/gcov/gcc_4_7.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/gcov/gcc_4_7.c b/kernel/gcov/gcc_4_7.c index ec37563674d6..908fdf5098c3 100644 --- a/kernel/gcov/gcc_4_7.c +++ b/kernel/gcov/gcc_4_7.c @@ -68,7 +68,7 @@ struct gcov_fn_info { unsigned int ident; unsigned int lineno_checksum; unsigned int cfg_checksum; - struct gcov_ctr_info ctrs[0]; + struct gcov_ctr_info ctrs[]; }; /** |