On 2015/9/12 6:47, Andrew Morton wrote: > On Fri, 11 Sep 2015 10:02:29 +0800 Xishi Qiu <qiuxishi@xxxxxxxxxx> wrote: > >> Use IS_ALIGNED() to determine whether the shadow span two bytes. >> It generates less code and more readable. >> > > Please cc Andrey Ryabinin on kasan patches. Sorry, my mistake. > >> --- a/mm/kasan/kasan.c >> +++ b/mm/kasan/kasan.c >> @@ -120,7 +120,7 @@ static __always_inline bool memory_is_poisoned_8(unsigned long addr) >> if (memory_is_poisoned_1(addr + 7)) >> return true; >> >> - if (likely(((addr + 7) & KASAN_SHADOW_MASK) >= 7)) >> + if (likely(IS_ALIGNED(addr, 8))) >> return false; > > Wouldn't IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE) be more appropriate? > OK, I'll send V2. > But I'm not really sure what the original code is trying to do. > > if ((addr + 7) & 7) >= 7) > > can only evaluate true if ((addr + 7) & 7) equals 7, so the ">=" could > be "==". > I think it should be "==", the value will not "> 7" > I think. The code looks a bit weird. A code comment would help. > > And how come memory_is_poisoned_16() does IS_ALIGNED(addr, 8)? Should > it be 16? No, it is to determine whether the shadow span two bytes(8 bytes, not 16). Thanks, Xishi Qiu > > > . > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>