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authorGustavo A. R. Silva <gustavo@embeddedor.com>2020-02-21 09:06:12 -0600
committerVasily Gorbik <gor@linux.ibm.com>2020-02-27 16:02:21 +0100
commitfa226f1d81e2d3798d30eaa14550d7f35c35e6f3 (patch)
tree2063b7d5c04db419fe443d7a2aa39e1cc21cbe4e /arch/s390/appldata
parentd5d006fa0927c34fa083c8d48e33b1c30b29fd1b (diff)
s390: 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") Link: https://lkml.kernel.org/r/20200221150612.GA9717@embeddedor Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'arch/s390/appldata')
-rw-r--r--arch/s390/appldata/appldata_os.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/s390/appldata/appldata_os.c b/arch/s390/appldata/appldata_os.c
index 54f375627532..8bf46d705957 100644
--- a/arch/s390/appldata/appldata_os.c
+++ b/arch/s390/appldata/appldata_os.c
@@ -75,7 +75,7 @@ struct appldata_os_data {
(waiting for I/O) */
/* per cpu data */
- struct appldata_os_per_cpu os_cpu[0];
+ struct appldata_os_per_cpu os_cpu[];
} __attribute__((packed));
static struct appldata_os_data *appldata_os_data;