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authorGustavo A. R. Silva <gustavo@embeddedor.com>2020-03-06 19:51:05 +0300
committerDavid Sterba <dsterba@suse.com>2020-03-23 19:01:53 +0300
commit7593f4c53c699699c6968a5fdd795d0fdf99a65d (patch)
tree9b47e36262bf0f8b2d33e20129fce71c8a5ff600
parent17b238acf7c665e5c1eb44a31be10299fcbf8858 (diff)
downloadlinux-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>
-rw-r--r--fs/btrfs/rcu-string.h2
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)