slab: use the lock on alien_cache, instead of the lock on array_cache

Now, we have separate alien_cache structure, so it'd be better to hold
the lock on alien_cache while manipulating alien_cache.  After that, we
don't need the lock on array_cache, so remove it.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/slab.c b/mm/slab.c
index de91d6f..e4ce73c 100644 (file)
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -191,7 +191,6 @@ struct array_cache {
        unsigned int limit;
        unsigned int batchcount;
        unsigned int touched;
-       spinlock_t lock;
        void *entry[];  /*
                         * Must have this definition in here for the proper
                         * alignment of array_cache. Also simplifies accessing
@@ -512,7 +511,7 @@ static void slab_set_lock_classes(struct kmem_cache *cachep,
                return;
        for_each_node(r) {
                if (alc[r])
-                       lockdep_set_class(&(alc[r]->ac.lock), alc_key);
+                       lockdep_set_class(&(alc[r]->lock), alc_key);
        }
 }
 
@@ -811,7 +810,6 @@ static void init_arraycache(struct array_cache *ac, int limit, int batch)
                ac->limit = limit;
                ac->batchcount = batch;
                ac->touched = 0;
-               spin_lock_init(&ac->lock);
        }
 }
 
@@ -1010,6 +1008,7 @@ static struct alien_cache *__alloc_alien_cache(int node, int entries,
 
        alc = kmalloc_node(memsize, gfp, node);
        init_arraycache(&alc->ac, entries, batch);
+       spin_lock_init(&alc->lock);
        return alc;
 }
 
@@ -1086,9 +1085,9 @@ static void reap_alien(struct kmem_cache *cachep, struct kmem_cache_node *n)
 
                if (alc) {
                        ac = &alc->ac;
-                       if (ac->avail && spin_trylock_irq(&ac->lock)) {
+                       if (ac->avail && spin_trylock_irq(&alc->lock)) {
                                __drain_alien_cache(cachep, ac, node);
-                               spin_unlock_irq(&ac->lock);
+                               spin_unlock_irq(&alc->lock);
                        }
                }
        }
@@ -1106,9 +1105,9 @@ static void drain_alien_cache(struct kmem_cache *cachep,
                alc = alien[i];
                if (alc) {
                        ac = &alc->ac;
-                       spin_lock_irqsave(&ac->lock, flags);
+                       spin_lock_irqsave(&alc->lock, flags);
                        __drain_alien_cache(cachep, ac, i);
-                       spin_unlock_irqrestore(&ac->lock, flags);
+                       spin_unlock_irqrestore(&alc->lock, flags);
                }
        }
 }
@@ -1136,13 +1135,13 @@ static inline int cache_free_alien(struct kmem_cache *cachep, void *objp)
        if (n->alien && n->alien[nodeid]) {
                alien = n->alien[nodeid];
                ac = &alien->ac;
-               spin_lock(&ac->lock);
+               spin_lock(&alien->lock);
                if (unlikely(ac->avail == ac->limit)) {
                        STATS_INC_ACOVERFLOW(cachep);
                        __drain_alien_cache(cachep, ac, nodeid);
                }
                ac_put_obj(cachep, ac, objp);
-               spin_unlock(&ac->lock);
+               spin_unlock(&alien->lock);
        } else {
                n = get_node(cachep, nodeid);
                spin_lock(&n->list_lock);
@@ -1613,10 +1612,6 @@ void __init kmem_cache_init(void)
 
                memcpy(ptr, cpu_cache_get(kmem_cache),
                       sizeof(struct arraycache_init));
-               /*
-                * Do not assume that spinlocks can be initialized via memcpy:
-                */
-               spin_lock_init(&ptr->lock);
 
                kmem_cache->array[smp_processor_id()] = ptr;
 
@@ -1626,10 +1621,6 @@ void __init kmem_cache_init(void)
                       != &initarray_generic.cache);
                memcpy(ptr, cpu_cache_get(kmalloc_caches[INDEX_AC]),
                       sizeof(struct arraycache_init));
-               /*
-                * Do not assume that spinlocks can be initialized via memcpy:
-                */
-               spin_lock_init(&ptr->lock);
 
                kmalloc_caches[INDEX_AC]->array[smp_processor_id()] = ptr;
        }