>I really did not like this part: >#ifdef CONFIG_SPARC64 > BUG_ON(((u64)location >> (u64)32) != (u64)0); >#endif /* CONFIG_SPARC64 */ > >I think it should be safe to do: > > BUG_ON(((unsigned long)location >> (unsigned long)32) != > (unsigned long)0); No, you can't safely shift a 32-bit value by 32 bits (the compiler is allowed to turn this into a shift of 0 bits for instance, by using a 5-bit mask for the shift distance). However it should be safe to do this, which is exactly the same in practice: BUG_ON((((unsigned long)location >> 31) >> 1) != (unsigned long)0); >But I did not really see the point of the BUG_ON in the first place, >and my limited digging did not turn up when it was added. Not sure who uses it and why it was added, but it's equivalent to: BUG_ON((unsigned long)location > 0xffffffff); which I personally prefer to the shift version -- I think it makes the intent more obvious -- but this might still draw a warning about being always-false on 32-bit. Of course, if gcc gets any smarter, so might the shift version. Chris -- To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
