From fa226f1d81e2d3798d30eaa14550d7f35c35e6f3 Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Fri, 21 Feb 2020 09:06:12 -0600 Subject: 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 Signed-off-by: Vasily Gorbik --- arch/s390/appldata/appldata_os.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/s390') 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; -- cgit v1.2.3