mm/zswap: change zswap_pool kref to percpu_ref

[linux-2.6-microblaze.git] / mm / zswap.c

diff --git a/mm/zswap.c b/mm/zswap.c
index 0141c45..da90933 100644 (file)
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -173,7 +173,7 @@ struct crypto_acomp_ctx {
 struct zswap_pool {
        struct zpool *zpools[ZSWAP_NR_ZPOOLS];
        struct crypto_acomp_ctx __percpu *acomp_ctx;
-       struct kref kref;
+       struct percpu_ref ref;
        struct list_head list;
        struct work_struct release_work;
        struct hlist_node node;
@@ -305,6 +305,7 @@ static void zswap_update_total_size(void)
 /*********************************
 * pool functions
 **********************************/
+static void __zswap_pool_empty(struct percpu_ref *ref);
 
 static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
 {
@@ -358,13 +359,18 @@ static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
        /* being the current pool takes 1 ref; this func expects the
         * caller to always add the new pool as the current pool
         */
-       kref_init(&pool->kref);
+       ret = percpu_ref_init(&pool->ref, __zswap_pool_empty,
+                             PERCPU_REF_ALLOW_REINIT, GFP_KERNEL);
+       if (ret)
+               goto ref_fail;
        INIT_LIST_HEAD(&pool->list);
 
        zswap_pool_debug("created", pool);
 
        return pool;
 
+ref_fail:
+       cpuhp_state_remove_instance(CPUHP_MM_ZSWP_POOL_PREPARE, &pool->node);
 error:
        if (pool->acomp_ctx)
                free_percpu(pool->acomp_ctx);
@@ -437,8 +443,9 @@ static void __zswap_pool_release(struct work_struct *work)
 
        synchronize_rcu();
 
-       /* nobody should have been able to get a kref... */
-       WARN_ON(kref_get_unless_zero(&pool->kref));
+       /* nobody should have been able to get a ref... */
+       WARN_ON(!percpu_ref_is_zero(&pool->ref));
+       percpu_ref_exit(&pool->ref);
 
        /* pool is now off zswap_pools list and has no references. */
        zswap_pool_destroy(pool);
@@ -446,13 +453,13 @@ static void __zswap_pool_release(struct work_struct *work)
 
 static struct zswap_pool *zswap_pool_current(void);
 
-static void __zswap_pool_empty(struct kref *kref)
+static void __zswap_pool_empty(struct percpu_ref *ref)
 {
        struct zswap_pool *pool;
 
-       pool = container_of(kref, typeof(*pool), kref);
+       pool = container_of(ref, typeof(*pool), ref);
 
-       spin_lock(&zswap_pools_lock);
+       spin_lock_bh(&zswap_pools_lock);
 
        WARN_ON(pool == zswap_pool_current());
 
@@ -461,7 +468,7 @@ static void __zswap_pool_empty(struct kref *kref)
        INIT_WORK(&pool->release_work, __zswap_pool_release);
        schedule_work(&pool->release_work);
 
-       spin_unlock(&zswap_pools_lock);
+       spin_unlock_bh(&zswap_pools_lock);
 }
 
 static int __must_check zswap_pool_get(struct zswap_pool *pool)
@@ -469,12 +476,12 @@ static int __must_check zswap_pool_get(struct zswap_pool *pool)
        if (!pool)
                return 0;
 
-       return kref_get_unless_zero(&pool->kref);
+       return percpu_ref_tryget(&pool->ref);
 }
 
 static void zswap_pool_put(struct zswap_pool *pool)
 {
-       kref_put(&pool->kref, __zswap_pool_empty);
+       percpu_ref_put(&pool->ref);
 }
 
 static struct zswap_pool *__zswap_pool_current(void)
@@ -591,7 +598,7 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
                return -EINVAL;
        }
 
-       spin_lock(&zswap_pools_lock);
+       spin_lock_bh(&zswap_pools_lock);
 
        pool = zswap_pool_find_get(type, compressor);
        if (pool) {
@@ -600,17 +607,28 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
                list_del_rcu(&pool->list);
        }
 
-       spin_unlock(&zswap_pools_lock);
+       spin_unlock_bh(&zswap_pools_lock);
 
        if (!pool)
                pool = zswap_pool_create(type, compressor);
+       else {
+               /*
+                * Restore the initial ref dropped by percpu_ref_kill()
+                * when the pool was decommissioned and switch it again
+                * to percpu mode.
+                */
+               percpu_ref_resurrect(&pool->ref);
+
+               /* Drop the ref from zswap_pool_find_get(). */
+               zswap_pool_put(pool);
+       }
 
        if (pool)
                ret = param_set_charp(s, kp);
        else
                ret = -EINVAL;
 
-       spin_lock(&zswap_pools_lock);
+       spin_lock_bh(&zswap_pools_lock);
 
        if (!ret) {
                put_pool = zswap_pool_current();
@@ -625,7 +643,7 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
                put_pool = pool;
        }
 
-       spin_unlock(&zswap_pools_lock);
+       spin_unlock_bh(&zswap_pools_lock);
 
        if (!zswap_has_pool && !pool) {
                /* if initial pool creation failed, and this pool creation also
@@ -642,7 +660,7 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
         * or the new pool we failed to add
         */
        if (put_pool)
-               zswap_pool_put(put_pool);
+               percpu_ref_kill(&put_pool->ref);
 
        return ret;
 }