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authorGustavo A. R. Silva <gustavo@embeddedor.com>2020-03-23 19:14:37 -0500
committerGustavo A. R. Silva <gustavo@embeddedor.com>2020-04-18 15:44:56 -0500
commitfe946db6ca851a0cd8c2f9c9dd96ef74e051cf2f (patch)
treecbcc6d5b8c0f668dfeb174315fcf8c4421cadd10 /include
parent9dd8bb5f8c449e87cc0084a118673c6d4182bab2 (diff)
sched: topology.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>
Diffstat (limited to 'include')
-rw-r--r--include/linux/sched/topology.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h
index af9319e4cfb9..95253ad792b0 100644
--- a/include/linux/sched/topology.h
+++ b/include/linux/sched/topology.h
@@ -142,7 +142,7 @@ struct sched_domain {
* by attaching extra space to the end of the structure,
* depending on how many CPUs the kernel has booted up with)
*/
- unsigned long span[0];
+ unsigned long span[];
};
static inline struct cpumask *sched_domain_span(struct sched_domain *sd)