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author | Gustavo A. R. Silva <gustavoars@kernel.org> | 2020-05-07 22:25:24 +0300 |
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committer | Mika Westerberg <mika.westerberg@linux.intel.com> | 2020-05-11 13:29:30 +0300 |
commit | 913b99f70feb1cd9fb4bbcb302a029b4b9bee454 (patch) | |
tree | 8b31bac8f0d43aa9f0ba817d50b26ff6c42e34c1 /include/linux/thunderbolt.h | |
parent | 57d8df68eb53cc15e5bdfc14bfb28a18543109eb (diff) | |
download | linux-913b99f70feb1cd9fb4bbcb302a029b4b9bee454.tar.xz |
thunderbolt: Replace zero-length array with flexible-array
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]
sizeof(flexible-array-member) triggers a warning because flexible array
members have incomplete type[1]. There are some instances of code in
which the sizeof operator is being incorrectly/erroneously applied to
zero-length arrays and the result is zero. Such instances may be hiding
some bugs. So, this work (flexible-array member conversions) will also
help to get completely rid of those sorts of issues.
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 <gustavoars@kernel.org>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Diffstat (limited to 'include/linux/thunderbolt.h')
-rw-r--r-- | include/linux/thunderbolt.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/thunderbolt.h b/include/linux/thunderbolt.h index ece782ef5466..ff397c0d5c07 100644 --- a/include/linux/thunderbolt.h +++ b/include/linux/thunderbolt.h @@ -80,7 +80,7 @@ struct tb { int index; enum tb_security_level security_level; size_t nboot_acl; - unsigned long privdata[0]; + unsigned long privdata[]; }; extern struct bus_type tb_bus_type; |