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author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-03-23 19:51:46 -0500 |
---|---|---|
committer | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-04-18 15:44:56 -0500 |
commit | d6cdad870358128c1e753e6258e295ab8a5a2429 (patch) | |
tree | eb21c55e5066118b84fa19361a9e9bd3d62a46c6 | |
parent | 06ccf63da5d8e90e4dff8b741972a9b279b5bf4c (diff) | |
download | linux-d6cdad870358128c1e753e6258e295ab8a5a2429.tar.bz2 |
uapi: linux: dlm_device.h: 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>
-rw-r--r-- | include/uapi/linux/dlm_device.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/include/uapi/linux/dlm_device.h b/include/uapi/linux/dlm_device.h index f880d2831160..e83954c69fff 100644 --- a/include/uapi/linux/dlm_device.h +++ b/include/uapi/linux/dlm_device.h @@ -45,13 +45,13 @@ struct dlm_lock_params { void __user *bastaddr; struct dlm_lksb __user *lksb; char lvb[DLM_USER_LVB_LEN]; - char name[0]; + char name[]; }; struct dlm_lspace_params { __u32 flags; __u32 minor; - char name[0]; + char name[]; }; struct dlm_purge_params { |