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authorGustavo A. R. Silva <gustavoars@kernel.org>2020-05-07 14:25:24 -0500
committerMika Westerberg <mika.westerberg@linux.intel.com>2020-05-11 13:29:30 +0300
commit913b99f70feb1cd9fb4bbcb302a029b4b9bee454 (patch)
tree8b31bac8f0d43aa9f0ba817d50b26ff6c42e34c1 /include/linux/thunderbolt.h
parent57d8df68eb53cc15e5bdfc14bfb28a18543109eb (diff)
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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.h2
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;