diff options
| author | Gustavo A. R. Silva | 2020-03-23 18:36:10 -0500 |
|---|---|---|
| committer | Gustavo A. R. Silva | 2020-04-18 15:44:55 -0500 |
| commit | 307ed94c37f842676d336cf5f2162022f4d7cdc4 (patch) | |
| tree | 503eb8493687e70973dec0d825030926eaae6d6d | |
| parent | 859b494111b196853fd8c1852c6b57ef33738b50 (diff) | |
memcontrol.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>
| -rw-r--r-- | include/linux/memcontrol.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 1b4150ff64be..d275c72c4f8e 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -106,7 +106,7 @@ struct lruvec_stat { */ struct memcg_shrinker_map { struct rcu_head rcu; - unsigned long map[0]; + unsigned long map[]; }; /* @@ -148,7 +148,7 @@ struct mem_cgroup_threshold_ary { /* Size of entries[] */ unsigned int size; /* Array of thresholds */ - struct mem_cgroup_threshold entries[0]; + struct mem_cgroup_threshold entries[]; }; struct mem_cgroup_thresholds { |