linux-kernel - RE: [PATCH 10/23] make atomic_read() and atomic

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Message-ID: <Pine.LNX.4.64.0708141509300.32420@schroedinger.engr.sgi.com>
Date:	Tue, 14 Aug 2007 15:11:09 -0700 (PDT)
From:	Christoph Lameter <clameter@....com>
To:	"Luck, Tony" <tony.luck@...el.com>
cc:	Chris Snook <csnook@...hat.com>, linux-arch@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	akpm@...ux-foundation.org, paulmck@...ux.vnet.ibm.com,
	Segher Boessenkool <segher@...nel.crashing.org>,
	Chris Friesen <cfriesen@...tel.com>,
	"Robert P. J. Day" <rpjday@...dspring.com>
Subject: RE: [PATCH 10/23] make atomic_read() and atomic_set() behavior
 consistent on ia64

On Tue, 14 Aug 2007, Luck, Tony wrote:

> I re-tried the macros ... the three warnings from mm/slub.c all result in
> broken code ... and quite rightly too, they all come from code that does:
> 
> 	atomic_read(&n->nr_slabs)
> 
> But the nr_slabs field is an atomic_long_t, so we shouldn't be using
> atomic_read().  I didn't spot these last time around because I was using
> slab, not slub for the previous build.

Hmmmm...  Strange that this did not cause failures before on any other 
platforms?


Fix atomic_read's in slub

Signed-off-by: Christoph Lameter <clameter@....com>

diff --git a/mm/slub.c b/mm/slub.c
index 69d02e3..0c106d7 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3112,7 +3112,7 @@ static int list_locations(struct kmem_cache *s, char *buf,
 		unsigned long flags;
 		struct page *page;
 
-		if (!atomic_read(&n->nr_slabs))
+		if (!atomic_long_read(&n->nr_slabs))
 			continue;
 
 		spin_lock_irqsave(&n->list_lock, flags);
@@ -3247,7 +3247,7 @@ static unsigned long slab_objects(struct kmem_cache *s,
 		}
 
 		if (flags & SO_FULL) {
-			int full_slabs = atomic_read(&n->nr_slabs)
+			int full_slabs = atomic_long_read(&n->nr_slabs)
 					- per_cpu[node]
 					- n->nr_partial;
 
@@ -3283,7 +3283,7 @@ static int any_slab_objects(struct kmem_cache *s)
 	for_each_node(node) {
 		struct kmem_cache_node *n = get_node(s, node);
 
-		if (n->nr_partial || atomic_read(&n->nr_slabs))
+		if (n->nr_partial || atomic_long_read(&n->nr_slabs))
 			return 1;
 	}
 	return 0;
-
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