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authorGustavo A. R. Silva2020-03-23 18:36:10 -0500
committerGustavo A. R. Silva2020-04-18 15:44:55 -0500
commit307ed94c37f842676d336cf5f2162022f4d7cdc4 (patch)
tree503eb8493687e70973dec0d825030926eaae6d6d
parent859b494111b196853fd8c1852c6b57ef33738b50 (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.h4
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 {