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authorGustavo A. R. Silva <gustavoars@kernel.org>2020-05-07 21:53:29 +0300
committerWolfram Sang <wsa@kernel.org>2020-05-15 12:23:49 +0300
commit8695e0b1b964f6d7caee667f14dceb7e8a4a3b3c (patch)
tree08c7154b74010b312a1bf7a9cafe9eae10092306 /include/linux
parente9d1a0a41d4486955e96552293c1fcf1fce61602 (diff)
downloadlinux-8695e0b1b964f6d7caee667f14dceb7e8a4a3b3c.tar.xz
i2c: mux: 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> Reviewed-by: Peter Rosin <peda@axentia.se> Signed-off-by: Wolfram Sang <wsa@kernel.org>
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/i2c-mux.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/i2c-mux.h b/include/linux/i2c-mux.h
index c5a977320f82..98ef73b7c8fd 100644
--- a/include/linux/i2c-mux.h
+++ b/include/linux/i2c-mux.h
@@ -29,7 +29,7 @@ struct i2c_mux_core {
int num_adapters;
int max_adapters;
- struct i2c_adapter *adapter[0];
+ struct i2c_adapter *adapter[];
};
struct i2c_mux_core *i2c_mux_alloc(struct i2c_adapter *parent,