linux-stable/fs/ocfs2/dlm
Gustavo A. R. Silva 8cb92435e2 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 7649773293 ("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>
2020-04-02 09:35:25 -07:00
..
Makefile ocfs2: make local header paths relative to C files 2020-01-31 10:30:36 -08:00
dlmapi.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 145 2019-05-30 11:25:18 -07:00
dlmast.c ocfs2: make local header paths relative to C files 2020-01-31 10:30:36 -08:00
dlmcommon.h ocfs2: dlm: replace zero-length array with flexible-array member 2020-04-02 09:35:25 -07:00
dlmconvert.c ocfs2: make local header paths relative to C files 2020-01-31 10:30:36 -08:00
dlmconvert.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 145 2019-05-30 11:25:18 -07:00
dlmdebug.c ocfs2: make local header paths relative to C files 2020-01-31 10:30:36 -08:00
dlmdebug.h ocfs2: further debugfs cleanups 2019-09-24 15:54:07 -07:00
dlmdomain.c ocfs2: make local header paths relative to C files 2020-01-31 10:30:36 -08:00
dlmdomain.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 145 2019-05-30 11:25:18 -07:00
dlmlock.c ocfs2: make local header paths relative to C files 2020-01-31 10:30:36 -08:00
dlmmaster.c ocfs2: remove unused macros 2020-04-02 09:35:25 -07:00
dlmrecovery.c ocfs2/dlm: remove redundant assignment to ret 2020-01-31 10:30:36 -08:00
dlmthread.c ocfs2: remove dlm_lock_is_remote 2020-04-02 09:35:25 -07:00
dlmunlock.c ocfs2: make local header paths relative to C files 2020-01-31 10:30:36 -08:00