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| author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-04-02 07:03:48 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-04-02 19:35:25 +0300 |
| commit | 3c9210d45d50edd13aca45131522211b93c7812d (patch) | |
| tree | fd4cd4626c15f51f5337c85fdc6be1a10e426b88 /fs/ocfs2/journal.c | |
| parent | 185a73216f2d5fbae2afa6345c2d53eae7c8606f (diff) | |
| download | linux-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.c | 2 |
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) |