linux-kernel - [PATCH 14/16] slab: Replace smp_read_barrier_depends() with lockless

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Message-Id: <1415906662-4576-15-git-send-email-bobby.prani@gmail.com>
Date:	Thu, 13 Nov 2014 14:24:20 -0500
From:	Pranith Kumar <bobby.prani@...il.com>
To:	Christoph Lameter <cl@...ux.com>,
	Pekka Enberg <penberg@...nel.org>,
	David Rientjes <rientjes@...gle.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-mm@...ck.org (open list:SLAB ALLOCATOR),
	linux-kernel@...r.kernel.org (open list)
Cc:	paulmck@...ux.vnet.ibm.com
Subject: [PATCH 14/16] slab: Replace smp_read_barrier_depends() with lockless_dereference()

Recently lockless_dereference() was added which can be used in place of
hard-coding smp_read_barrier_depends(). The following PATCH makes the change.

Signed-off-by: Pranith Kumar <bobby.prani@...il.com>
---
 mm/slab.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/slab.h b/mm/slab.h
index 3347fd7..1cf40054 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -209,15 +209,15 @@ cache_from_memcg_idx(struct kmem_cache *s, int idx)
 
 	rcu_read_lock();
 	params = rcu_dereference(s->memcg_params);
-	cachep = params->memcg_caches[idx];
-	rcu_read_unlock();
 
 	/*
 	 * Make sure we will access the up-to-date value. The code updating
 	 * memcg_caches issues a write barrier to match this (see
 	 * memcg_register_cache()).
 	 */
-	smp_read_barrier_depends();
+	cachep = lockless_dereference(params->memcg_caches[idx]);
+	rcu_read_unlock();
+
 	return cachep;
 }
 
-- 
1.9.1

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