Re: [net-next PATCH] net: codel: Avoid undefined behavior from signed overflow
From: Eric Dumazet <hidden>
Date: 2013-10-31 15:10:43
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
On Thu, 2013-10-31 at 15:15 +0100, Jesper Dangaard Brouer wrote:
Okay, I'll cook up another patch, after work. Adding all the typecheck() stuff, just bloats the code. Would it be better/okay just to do?: (s32)((u32)(a) - (u32)(b)) > 0)
What about using the existing codel types ?
diff --git a/include/net/codel.h b/include/net/codel.h
index 389cf62..89a7781 100644
--- a/include/net/codel.h
+++ b/include/net/codel.h@@ -72,7 +72,12 @@ static inline codel_time_t codel_get_time(void) return ns >> CODEL_SHIFT; } -#define codel_time_after(a, b) ((s32)(a) - (s32)(b) > 0) +static inline bool codel_time_after(codel_time_t a, codel_time_t b) +{ + codel_tdiff_t delta = a - b; + + return delta >= 0; +} #define codel_time_after_eq(a, b) ((s32)(a) - (s32)(b) >= 0) #define codel_time_before(a, b) ((s32)(a) - (s32)(b) < 0) #define codel_time_before_eq(a, b) ((s32)(a) - (s32)(b) <= 0)
You need of course something similar for all variants.