From: Rusty Russell <rusty@rustcorp.com.au>
To: William Lee Irwin III <wli@holomorphy.com>
Cc: Andrew Morton <akpm@osdl.org>,
lkml - Kernel Mailing List <linux-kernel@vger.kernel.org>,
Paul Jackson <pj@sgi.com>, Linus Torvalds <torvalds@osdl.org>
Subject: Re: [PATCH] Fix cpu iterator on empty bitmask
Date: Wed, 28 Apr 2004 11:22:28 +1000 [thread overview]
Message-ID: <1083115347.30987.202.camel@bach> (raw)
In-Reply-To: <20040428000511.GU743@holomorphy.com>
On Wed, 2004-04-28 at 10:05, William Lee Irwin III wrote:
> On Wed, Apr 28, 2004 at 09:52:53AM +1000, Rusty Russell wrote:
> > Name: Fix cpumask iterator over empty cpu set
> > Status: Trivial
> > Can't use _ffs() without first checking for zero, and if bits beyond
> > NR_CPUS set it'll give bogus results. Use find_first_bit
>
> I sent in something equivalent to this along with a number of other
> fixes (cpus_shift_right() leaking junk bits in in and cpus_weight()
> and cpus_empty() and cpus_equal() and the like not ignoring tails) and
> got a NAK since it clashes with something Paul Jackson's doing.
Agreed, I'm pretty sure Paul's work doesn't make this mistake, but this
is a trivial patch for a real big which is causing oopses today.
Linus, please apply...
Rusty.
Name: Fix cpumask iterator over empty cpu set
Status: Trivial
Can't use _ffs() without first checking for zero, and if bits beyond
NR_CPUS set it'll give bogus results. Use find_first_bit
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .26180-linux-2.6.6-rc2-bk5/include/asm-generic/cpumask_arith.h .26180-linux-2.6.6-rc2-bk5.updated/include/asm-generic/cpumask_arith.h
--- .26180-linux-2.6.6-rc2-bk5/include/asm-generic/cpumask_arith.h 2004-01-10 13:59:33.000000000 +1100
+++ .26180-linux-2.6.6-rc2-bk5.updated/include/asm-generic/cpumask_arith.h 2004-04-28 09:50:23.000000000 +1000
@@ -43,7 +43,7 @@
#define cpus_promote(map) ({ map; })
#define cpumask_of_cpu(cpu) ({ ((cpumask_t)1) << (cpu); })
-#define first_cpu(map) __ffs(map)
+#define first_cpu(map) find_first_bit(&(map), NR_CPUS)
#define next_cpu(cpu, map) find_next_bit(&(map), NR_CPUS, cpu + 1)
#endif /* __ASM_GENERIC_CPUMASK_ARITH_H */
--
Anyone who quotes me in their signature is an idiot -- Rusty Russell
next prev parent reply other threads:[~2004-04-28 1:23 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-04-27 23:52 [PATCH] Fix cpu iterator on empty bitmask Rusty Russell
2004-04-28 0:05 ` William Lee Irwin III
2004-04-28 1:22 ` Rusty Russell [this message]
2004-04-28 1:31 ` Paul Jackson
2004-04-28 1:57 ` William Lee Irwin III
2004-04-28 2:18 ` Paul Jackson
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