diff options
| author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-04-01 21:03:55 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-04-02 09:35:25 -0700 |
| commit | 8cb92435e2fdd044d6e6e3a47eb761f0d024eb85 (patch) | |
| tree | 572896cf39c2ba83d77a7dadfba09ff0202b8129 /fs/ocfs2 | |
| parent | fa803cf8f39feba691732a78e47797c5dc388ba2 (diff) | |
ocfs2: dlm: 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://urldefense.com/v3/__https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html__;!!GqivPVa7Brio!OVOYL_CouISa5L1Lw-20EEFQntw6cKMx-j8UdY4z78uYgzKBUFcfpn50GaurvbV5v7YiUA$
[2] https://urldefense.com/v3/__https://github.com/KSPP/linux/issues/21__;!!GqivPVa7Brio!OVOYL_CouISa5L1Lw-20EEFQntw6cKMx-j8UdY4z78uYgzKBUFcfpn50GaurvbXs8Eh8eg$
[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/20200309202016.GA8210@embeddedor
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/ocfs2')
| -rw-r--r-- | fs/ocfs2/dlm/dlmcommon.h | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/fs/ocfs2/dlm/dlmcommon.h b/fs/ocfs2/dlm/dlmcommon.h index 0463dce65bb2..c8a444622faa 100644 --- a/fs/ocfs2/dlm/dlmcommon.h +++ b/fs/ocfs2/dlm/dlmcommon.h @@ -564,7 +564,7 @@ struct dlm_migratable_lockres // 48 bytes u8 lvb[DLM_LVB_LEN]; // 112 bytes - struct dlm_migratable_lock ml[0]; // 16 bytes each, begins at byte 112 + struct dlm_migratable_lock ml[]; // 16 bytes each, begins at byte 112 }; #define DLM_MIG_LOCKRES_MAX_LEN \ (sizeof(struct dlm_migratable_lockres) + \ @@ -601,7 +601,7 @@ struct dlm_convert_lock u8 name[O2NM_MAX_NAME_LEN]; - s8 lvb[0]; + s8 lvb[]; }; #define DLM_CONVERT_LOCK_MAX_LEN (sizeof(struct dlm_convert_lock)+DLM_LVB_LEN) @@ -616,7 +616,7 @@ struct dlm_unlock_lock u8 name[O2NM_MAX_NAME_LEN]; - s8 lvb[0]; + s8 lvb[]; }; #define DLM_UNLOCK_LOCK_MAX_LEN (sizeof(struct dlm_unlock_lock)+DLM_LVB_LEN) @@ -632,7 +632,7 @@ struct dlm_proxy_ast u8 name[O2NM_MAX_NAME_LEN]; - s8 lvb[0]; + s8 lvb[]; }; #define DLM_PROXY_AST_MAX_LEN (sizeof(struct dlm_proxy_ast)+DLM_LVB_LEN) |