From: Gustavo A. R. Silva Date: Wed, 12 Feb 2020 23:56:42 +0000 (-0600) Subject: mfd: omap-usb-tll: Replace zero-length array with flexible-array member X-Git-Tag: v5.15~4107^2~17 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=a0c8498c076d0338860df7e45e5e6f48158a02d8;p=platform%2Fkernel%2Flinux-starfive.git mfd: omap-usb-tll: 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 Signed-off-by: Lee Jones --- diff --git a/drivers/mfd/omap-usb-tll.c b/drivers/mfd/omap-usb-tll.c index 265f5e3..1cf259a 100644 --- a/drivers/mfd/omap-usb-tll.c +++ b/drivers/mfd/omap-usb-tll.c @@ -99,7 +99,7 @@ struct usbtll_omap { void __iomem *base; int nch; /* num. of channels */ - struct clk *ch_clk[0]; /* must be the last member */ + struct clk *ch_clk[]; /* must be the last member */ }; /*-------------------------------------------------------------------------*/