kernel_optimize_test/kernel/gcov
Gustavo A. R. Silva 7ff87182d1 gcov: gcc_3_4: 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 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Oberparleiter <oberpar@linux.ibm.com>
Link: http://lkml.kernel.org/r/20200302224501.GA14175@embeddedor
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07 10:43:44 -07:00
..
base.c gcov: clang support 2019-05-14 19:52:51 -07:00
clang.c gcov: clang support 2019-05-14 19:52:51 -07:00
fs.c gcov: no need to check return value of debugfs_create functions 2019-06-03 16:18:12 +02:00
gcc_3_4.c gcov: gcc_3_4: replace zero-length array with flexible-array member 2020-04-07 10:43:44 -07:00
gcc_4_7.c gcov: gcc_4_7: replace zero-length array with flexible-array member 2020-04-07 10:43:44 -07:00
gcc_base.c gcov: clang: move common GCC code into gcc_base.c 2019-05-14 19:52:51 -07:00
gcov.h gcov: clang support 2019-05-14 19:52:51 -07:00
Kconfig Revert "um: Enable CONFIG_CONSTRUCTORS" 2020-01-19 22:42:06 +01:00
Makefile gcov: clang support 2019-05-14 19:52:51 -07:00