make sure swap arguments are the same type? (was: Re: [PATCH] crypto: rmd320 - use swap macro in rmd320_transform)
From: Joe Perches <joe@perches.com>
Date: 2018-07-18 18:31:20
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the rest · Maintainer:
Linus Torvalds
On Wed, 2018-07-18 at 12:19 -0500, Gustavo A. R. Silva wrote:
swap
Perhaps the swap macro should verify that the swap(a, b) arguments are the same type. Something like the patch below, but this patch causes a compilation failure on at least a couple cases that aren't obviously correct in net/netfilter/ipset/ip_set_bitmap_port.c where a u16 is swapped with a u32. and net/netfilter/ipset/ip_set_hash_netport.c where a single bit bitfield is swapped with a u8 --- include/linux/kernel.h | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index d6aac75b51ba..506b59e0da24 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h@@ -969,14 +969,19 @@ static inline void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { } */ #define clamp_val(val, lo, hi) clamp_t(typeof(val), val, lo, hi) - /** * swap - swap values of @a and @b * @a: first value * @b: second value + * @a and @b must be the same type */ -#define swap(a, b) \ - do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0) +#define swap(a, b) \ +do { \ + typeof(a) __tmp = (a); \ + BUILD_BUG_ON(!__same_type(typeof(a), typeof(b))); \ + (a) = (b); \ + (b) = __tmp; \ +} while (0) /* This counts to 12. Any more, it will return 13th argument. */ #define __COUNT_ARGS(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _n, X...) _n