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Date: Tue, 9 Aug 2011 18:38:21 +0900 From: Akinobu Mita <akinobu.mita@...il.com> To: Eric Dumazet <eric.dumazet@...il.com> Cc: linux-kernel@...r.kernel.org, Christoph Lameter <cl@...ux-foundation.org>, Pekka Enberg <penberg@...nel.org>, Matt Mackall <mpm@...enic.com>, linux-mm@...ck.org Subject: Re: [PATCH] slub: fix check_bytes() for slub debugging 2011/8/9 Eric Dumazet <eric.dumazet@...il.com>: >> > diff --git a/mm/slub.c b/mm/slub.c >> > index eb5a8f9..5695f92 100644 >> > --- a/mm/slub.c >> > +++ b/mm/slub.c >> > @@ -701,7 +701,7 @@ static u8 *check_bytes(u8 *start, u8 value, unsigned int bytes) >> > return check_bytes8(start, value, bytes); >> > >> > value64 = value | value << 8 | value << 16 | value << 24; >> > - value64 = value64 | value64 << 32; >> > + value64 = (value64 & 0xffffffff) | value64 << 32; >> > prefix = 8 - ((unsigned long)start) % 8; >> > >> > if (prefix) { >> >> Still buggy I am afraid. Could we use the following ? >> >> >> value64 = value; >> value64 |= value64 << 8; >> value64 |= value64 << 16; >> value64 |= value64 << 32; >> >> > > Well, 'buggy' was not well chosen. > > Another possibility would be to use a multiply if arch has a fast > multiplier... > > > value64 = value; > #if defined(ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64 > value64 *= 0x0101010101010101; > #elif defined(ARCH_HAS_FAST_MULTIPLIER) > value64 *= 0x01010101; > value64 |= value64 << 32; > #else > value64 |= value64 << 8; > value64 |= value64 << 16; > value64 |= value64 << 32; > #endif I don't really care about which one should be used. So tell me if I need to resend it with this improvement. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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