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authorGustavo A. R. Silva <gustavo@embeddedor.com>2020-04-02 07:03:48 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2020-04-02 19:35:25 +0300
commit3c9210d45d50edd13aca45131522211b93c7812d (patch)
treefd4cd4626c15f51f5337c85fdc6be1a10e426b88 /fs/ocfs2/journal.c
parent185a73216f2d5fbae2afa6345c2d53eae7c8606f (diff)
downloadlinux-3c9210d45d50edd13aca45131522211b93c7812d.tar.xz
ocfs2: 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: Joseph Qi <joseph.qi@linux.alibaba.com> Cc: Mark Fasheh <mark@fasheh.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Junxiao Bi <junxiao.bi@oracle.com> Cc: Changwei Ge <gechangwei@live.cn> Cc: Gang He <ghe@suse.com> Cc: Jun Piao <piaojun@huawei.com> Link: http://lkml.kernel.org/r/20200213160244.GA6088@embeddedor Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/ocfs2/journal.c')
-rw-r--r--fs/ocfs2/journal.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
index 68ba354cf361..b425f0b01dce 100644
--- a/fs/ocfs2/journal.c
+++ b/fs/ocfs2/journal.c
@@ -91,7 +91,7 @@ enum ocfs2_replay_state {
struct ocfs2_replay_map {
unsigned int rm_slots;
enum ocfs2_replay_state rm_state;
- unsigned char rm_replay_slots[0];
+ unsigned char rm_replay_slots[];
};
static void ocfs2_replay_map_set_state(struct ocfs2_super *osb, int state)