mm/zswap: Convert pool to hotplug state machine

Install the callbacks via the state machine. Multi state is used to address the
per-pool notifier. Uppon adding of the intance the callback is invoked for all
online CPUs so the manual init can go.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-mm@kvack.org
Cc: Seth Jennings <sjenning@redhat.com>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20161126231350.10321-13-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 62f51a4..c7d0d76 100644 (file)
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -66,6 +66,7 @@ enum cpuhp_state {
        CPUHP_TRACE_RB_PREPARE,
        CPUHP_MM_ZS_PREPARE,
        CPUHP_MM_ZSWP_MEM_PREPARE,
+       CPUHP_MM_ZSWP_POOL_PREPARE,
        CPUHP_TIMERS_DEAD,
        CPUHP_NOTF_ERR_INJ_PREPARE,
        CPUHP_MIPS_SOC_PREPARE,

diff --git a/mm/zswap.c b/mm/zswap.c
index b13aa57..067a0d6 100644 (file)
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -118,7 +118,7 @@ struct zswap_pool {
        struct kref kref;
        struct list_head list;
        struct work_struct work;
-       struct notifier_block notifier;
+       struct hlist_node node;
        char tfm_name[CRYPTO_MAX_ALG_NAME];
 };
 
@@ -376,77 +376,34 @@ static int zswap_dstmem_dead(unsigned int cpu)
        return 0;
 }
 
-static int __zswap_cpu_comp_notifier(struct zswap_pool *pool,
-                                    unsigned long action, unsigned long cpu)
+static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
 {
+       struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node);
        struct crypto_comp *tfm;
 
-       switch (action) {
-       case CPU_UP_PREPARE:
-               if (WARN_ON(*per_cpu_ptr(pool->tfm, cpu)))
-                       break;
-               tfm = crypto_alloc_comp(pool->tfm_name, 0, 0);
-               if (IS_ERR_OR_NULL(tfm)) {
-                       pr_err("could not alloc crypto comp %s : %ld\n",
-                              pool->tfm_name, PTR_ERR(tfm));
-                       return NOTIFY_BAD;
-               }
-               *per_cpu_ptr(pool->tfm, cpu) = tfm;
-               break;
-       case CPU_DEAD:
-       case CPU_UP_CANCELED:
-               tfm = *per_cpu_ptr(pool->tfm, cpu);
-               if (!IS_ERR_OR_NULL(tfm))
-                       crypto_free_comp(tfm);
-               *per_cpu_ptr(pool->tfm, cpu) = NULL;
-               break;
-       default:
-               break;
-       }
-       return NOTIFY_OK;
-}
-
-static int zswap_cpu_comp_notifier(struct notifier_block *nb,
-                                  unsigned long action, void *pcpu)
-{
-       unsigned long cpu = (unsigned long)pcpu;
-       struct zswap_pool *pool = container_of(nb, typeof(*pool), notifier);
-
-       return __zswap_cpu_comp_notifier(pool, action, cpu);
-}
+       if (WARN_ON(*per_cpu_ptr(pool->tfm, cpu)))
+               return 0;
 
-static int zswap_cpu_comp_init(struct zswap_pool *pool)
-{
-       unsigned long cpu;
-
-       memset(&pool->notifier, 0, sizeof(pool->notifier));
-       pool->notifier.notifier_call = zswap_cpu_comp_notifier;
-
-       cpu_notifier_register_begin();
-       for_each_online_cpu(cpu)
-               if (__zswap_cpu_comp_notifier(pool, CPU_UP_PREPARE, cpu) ==
-                   NOTIFY_BAD)
-                       goto cleanup;
-       __register_cpu_notifier(&pool->notifier);
-       cpu_notifier_register_done();
+       tfm = crypto_alloc_comp(pool->tfm_name, 0, 0);
+       if (IS_ERR_OR_NULL(tfm)) {
+               pr_err("could not alloc crypto comp %s : %ld\n",
+                      pool->tfm_name, PTR_ERR(tfm));
+               return -ENOMEM;
+       }
+       *per_cpu_ptr(pool->tfm, cpu) = tfm;
        return 0;
-
-cleanup:
-       for_each_online_cpu(cpu)
-               __zswap_cpu_comp_notifier(pool, CPU_UP_CANCELED, cpu);
-       cpu_notifier_register_done();
-       return -ENOMEM;
 }
 
-static void zswap_cpu_comp_destroy(struct zswap_pool *pool)
+static int zswap_cpu_comp_dead(unsigned int cpu, struct hlist_node *node)
 {
-       unsigned long cpu;
+       struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node);
+       struct crypto_comp *tfm;
 
-       cpu_notifier_register_begin();
-       for_each_online_cpu(cpu)
-               __zswap_cpu_comp_notifier(pool, CPU_UP_CANCELED, cpu);
-       __unregister_cpu_notifier(&pool->notifier);
-       cpu_notifier_register_done();
+       tfm = *per_cpu_ptr(pool->tfm, cpu);
+       if (!IS_ERR_OR_NULL(tfm))
+               crypto_free_comp(tfm);
+       *per_cpu_ptr(pool->tfm, cpu) = NULL;
+       return 0;
 }
 
 /*********************************
@@ -527,6 +484,7 @@ static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
        struct zswap_pool *pool;
        char name[38]; /* 'zswap' + 32 char (max) num + \0 */
        gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM;
+       int ret;
 
        pool = kzalloc(sizeof(*pool), GFP_KERNEL);
        if (!pool) {
@@ -551,7 +509,9 @@ static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
                goto error;
        }
 
-       if (zswap_cpu_comp_init(pool))
+       ret = cpuhp_state_add_instance(CPUHP_MM_ZSWP_POOL_PREPARE,
+                                      &pool->node);
+       if (ret)
                goto error;
        pr_debug("using %s compressor\n", pool->tfm_name);
 
@@ -605,7 +565,7 @@ static void zswap_pool_destroy(struct zswap_pool *pool)
 {
        zswap_pool_debug("destroying", pool);
 
-       zswap_cpu_comp_destroy(pool);
+       cpuhp_state_remove_instance(CPUHP_MM_ZSWP_POOL_PREPARE, &pool->node);
        free_percpu(pool->tfm);
        zpool_destroy_pool(pool->zpool);
        kfree(pool);
@@ -1212,6 +1172,13 @@ static int __init init_zswap(void)
                goto dstmem_fail;
        }
 
+       ret = cpuhp_setup_state_multi(CPUHP_MM_ZSWP_POOL_PREPARE,
+                                     "mm/zswap_pool:prepare",
+                                     zswap_cpu_comp_prepare,
+                                     zswap_cpu_comp_dead);
+       if (ret)
+               goto hp_fail;
+
        pool = __zswap_pool_create_fallback();
        if (!pool) {
                pr_err("pool creation failed\n");
@@ -1228,6 +1195,8 @@ static int __init init_zswap(void)
        return 0;
 
 pool_fail:
+       cpuhp_remove_state_nocalls(CPUHP_MM_ZSWP_POOL_PREPARE);
+hp_fail:
        cpuhp_remove_state(CPUHP_MM_ZSWP_MEM_PREPARE);
 dstmem_fail:
        zswap_entry_cache_destroy();