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authorGustavo A. R. Silva <gustavo@embeddedor.com>2020-03-24 00:45:36 +0300
committerGustavo A. R. Silva <gustavo@embeddedor.com>2020-04-18 23:44:54 +0300
commit5a58ec8cfc8621f5bdbd610202f62f817e5da204 (patch)
treebff8a4872fa159de28db3f47541fc6e387eed086 /include
parentf36aaf8be421099103193c49796a14213d3be315 (diff)
downloadlinux-5a58ec8cfc8621f5bdbd610202f62f817e5da204.tar.xz
blk_types: 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>
Diffstat (limited to 'include')
-rw-r--r--include/linux/blk_types.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 70254ae11769..31eb92876be7 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -198,7 +198,7 @@ struct bio {
* double allocations for a small number of bio_vecs. This member
* MUST obviously be kept at the very end of the bio.
*/
- struct bio_vec bi_inline_vecs[0];
+ struct bio_vec bi_inline_vecs[];
};
#define BIO_RESET_BYTES offsetof(struct bio, bi_max_vecs)