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authorGustavo A. R. Silva <gustavo@embeddedor.com>2020-04-06 20:11:52 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-04-07 10:43:44 -0700
commitfba4168edecdd2781bcd83cb131977ec1157f87c (patch)
treee19148dba584f3e3fbf1cd697b793d568bb56746 /kernel
parent06d4f8152a01034b36591885321da54eb77398c1 (diff)
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.c2
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[];
};
/**