mirror of
https://github.com/torvalds/linux.git
synced 2024-11-10 22:21:40 +00:00
358369f03a
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]
sizeof(flexible-array-member) triggers a warning because flexible array
members have incomplete type[1]. There are some instances of code in
which the sizeof operator is being incorrectly/erroneously applied to
zero-length arrays and the result is zero. Such instances may be hiding
some bugs. So, this work (flexible-array member conversions) will also
help to get completely rid of those sorts of issues.
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 7649773293 ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Song Liu <songliubraving@fb.com>
18 lines
303 B
C
18 lines
303 B
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
#ifndef _LINEAR_H
|
|
#define _LINEAR_H
|
|
|
|
struct dev_info {
|
|
struct md_rdev *rdev;
|
|
sector_t end_sector;
|
|
};
|
|
|
|
struct linear_conf
|
|
{
|
|
struct rcu_head rcu;
|
|
sector_t array_sectors;
|
|
int raid_disks; /* a copy of mddev->raid_disks */
|
|
struct dev_info disks[];
|
|
};
|
|
#endif
|