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| author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-03-06 19:51:05 +0300 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2020-03-23 19:01:53 +0300 |
| commit | 7593f4c53c699699c6968a5fdd795d0fdf99a65d (patch) | |
| tree | 9b47e36262bf0f8b2d33e20129fce71c8a5ff600 /fs/btrfs | |
| parent | 17b238acf7c665e5c1eb44a31be10299fcbf8858 (diff) | |
| download | linux-7593f4c53c699699c6968a5fdd795d0fdf99a65d.tar.xz | |
btrfs: rcu-string: 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>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs')
| -rw-r--r-- | fs/btrfs/rcu-string.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/btrfs/rcu-string.h b/fs/btrfs/rcu-string.h index a97dc74a4d3d..5c1a617eb25d 100644 --- a/fs/btrfs/rcu-string.h +++ b/fs/btrfs/rcu-string.h @@ -8,7 +8,7 @@ struct rcu_string { struct rcu_head rcu; - char str[0]; + char str[]; }; static inline struct rcu_string *rcu_string_strdup(const char *src, gfp_t mask) |