From: Gustavo A. R. Silva Date: Thu, 13 Feb 2020 00:39:25 +0000 (-0600) Subject: dmaengine: ti: omap-dma: Replace zero-length array with flexible-array member X-Git-Tag: v5.10.7~2914^2~83 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=5ca3364a83b2d78590c3acd40a9edc716465f7af;p=platform%2Fkernel%2Flinux-rpi.git dmaengine: ti: omap-dma: 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 Acked-by: Peter Ujfalusi Link: https://lore.kernel.org/r/20200213003925.GA6906@embeddedor.com Signed-off-by: Vinod Koul --- diff --git a/drivers/dma/ti/omap-dma.c b/drivers/dma/ti/omap-dma.c index a014ab9..918301e 100644 --- a/drivers/dma/ti/omap-dma.c +++ b/drivers/dma/ti/omap-dma.c @@ -124,7 +124,7 @@ struct omap_desc { uint32_t csdp; /* CSDP value */ unsigned sglen; - struct omap_sg sg[0]; + struct omap_sg sg[]; }; enum {