diff options
author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-03-06 16:13:33 -0600 |
---|---|---|
committer | David Sterba <dsterba@suse.com> | 2020-03-23 17:01:54 +0100 |
commit | a8753ee3a859a519613641963464b38b9a79dc9c (patch) | |
tree | 6ba657cf3151b7a359406074231c2442feadc8d7 | |
parent | 7593f4c53c699699c6968a5fdd795d0fdf99a65d (diff) | |
download | linux-a8753ee3a859a519613641963464b38b9a79dc9c.tar.bz2 |
btrfs: scrub: 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>
-rw-r--r-- | fs/btrfs/scrub.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c index 16aa680134fd..adaf8ab694d5 100644 --- a/fs/btrfs/scrub.c +++ b/fs/btrfs/scrub.c @@ -149,7 +149,7 @@ struct scrub_parity { */ unsigned long *ebitmap; - unsigned long bitmap[0]; + unsigned long bitmap[]; }; struct scrub_ctx { |