From: Roland Dreier <rdreier@cisco.com>
To: Pekka J Enberg <penberg@cs.helsinki.fi>, torvalds@linux-foundation.org
Cc: Andi Kleen <ak@suse.de>, Christoph Lameter <clameter@sgi.com>,
linux-kernel@vger.kernel.org,
"Michael S. Tsirkin" <mst@dev.mellanox.co.il>
Subject: [PATCH] Fix ZERO_OR_NULL_PTR(ZERO_SIZE_PTR)
Date: Fri, 20 Jul 2007 12:13:20 -0700 [thread overview]
Message-ID: <adamyxqc2i7.fsf_-_@cisco.com> (raw)
In-Reply-To: <Pine.LNX.4.64.0707201017450.1209@sbz-30.cs.Helsinki.FI> (Pekka J. Enberg's message of "Fri, 20 Jul 2007 10:18:49 +0300 (EEST)")
The comparison with ZERO_SIZE_PTR in ZERO_OR_NULL_PTR() needs to be <=
(not just <) so that ZERO_OR_NULL_PTR(ZERO_SIZE_PTR) is 1.
Signed-off-by: Roland Dreier <rolandd@cisco.com>
---
I finally had time to reproduce Michael's crash and debug it. Linus's
patch is part of the story -- it doesn't help unless ZERO_OR_NULL_PTR()
is true. With this change the crash goes away, and it seems pretty
obviously correct to me (unless I'm seriously confused).
include/linux/slab.h | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 7d0ecc1..d859354 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -40,7 +40,7 @@
*/
#define ZERO_SIZE_PTR ((void *)16)
-#define ZERO_OR_NULL_PTR(x) ((unsigned long)(x) < \
+#define ZERO_OR_NULL_PTR(x) ((unsigned long)(x) <= \
(unsigned long)ZERO_SIZE_PTR)
/*
next prev parent reply other threads:[~2007-07-20 19:13 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-19 10:01 kmalloc zero size changes break i386 Andi Kleen
2007-07-19 14:08 ` Pekka Enberg
2007-07-19 15:17 ` Roland Dreier
2007-07-19 18:11 ` Linus Torvalds
2007-07-19 19:03 ` Pekka Enberg
2007-07-19 19:19 ` Linus Torvalds
2007-07-19 21:03 ` Andi Kleen
2007-07-20 7:12 ` Pekka J Enberg
2007-07-20 7:18 ` Pekka J Enberg
2007-07-20 19:13 ` Roland Dreier [this message]
2007-07-19 17:01 ` Andi Kleen
2007-07-19 15:57 ` Linus Torvalds
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