On Mon, 20 Jun 2011, Arnd Bergmann wrote: > On Monday 20 June 2011 20:48:49 Russell King - ARM Linux wrote: > > If it is the case that these structures do not require packing to get > > their desired layout, then they don't require packing, and the packed > > attribute should be dropped. > > Yes. But are you going to audit every other use of __packed in the kernel > to check if it is used on __iomem pointers? The compiler might tell us about it: diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h index d66605d..10c47e8 100644 --- a/arch/arm/include/asm/io.h +++ b/arch/arm/include/asm/io.h @@ -49,11 +49,11 @@ extern void __raw_readsl(const void __iomem *addr, void *data, int longlen); #define __raw_writeb(v,a) (__chk_io_ptr(a), *(volatile unsigned char __force *)(a) = (v)) #define __raw_writew(v,a) (__chk_io_ptr(a), *(volatile unsigned short __force *)(a) = (v)) -#define __raw_writel(v,a) (__chk_io_ptr(a), *(volatile unsigned int __force *)(a) = (v)) +#define __raw_writel(v,a) (__chk_io_ptr(a), BUILD_BUG_ON_ZERO(__alignof(*(int *)a) != 4), *(volatile unsigned int __force *)(a) = (v)) #define __raw_readb(a) (__chk_io_ptr(a), *(volatile unsigned char __force *)(a)) #define __raw_readw(a) (__chk_io_ptr(a), *(volatile unsigned short __force *)(a)) -#define __raw_readl(a) (__chk_io_ptr(a), *(volatile unsigned int __force *)(a)) +#define __raw_readl(a) (__chk_io_ptr(a), BUILD_BUG_ON_ZERO(__alignof(*(int *)a) != 4), *(volatile unsigned int __force *)(a)) /* * Architecture ioremap implementation. And similar for readh/writeh, given that your GCC version is preserving the alignment attribute across the cast of course. [...] Scratch that. The alignment of a void pointer dereference is 1. Nicolas -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
