Commit-ID:  ad7ed7708db9ff388450935645816d44bf08a56d
Gitweb:     http://git.kernel.org/tip/ad7ed7708db9ff388450935645816d44bf08a56d
Author:     Sebastian Andrzej Siewior <bige...@linutronix.de>
AuthorDate: Sun, 27 Nov 2016 00:13:39 +0100
Committer:  Thomas Gleixner <t...@linutronix.de>
CommitDate: Fri, 2 Dec 2016 00:52:36 +0100

mm/zswap: Convert dst-mem to hotplug state machine

Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.

Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de>
Cc: linux...@kvack.org
Cc: Seth Jennings <sjenn...@redhat.com>
Cc: r...@linutronix.de
Link: http://lkml.kernel.org/r/20161126231350.10321-12-bige...@linutronix.de
Signed-off-by: Thomas Gleixner <t...@linutronix.de>

---
 include/linux/cpuhotplug.h |  1 +
 mm/zswap.c                 | 73 +++++++++++-----------------------------------
 2 files changed, 18 insertions(+), 56 deletions(-)

diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 9f29dd9..62f51a4 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -65,6 +65,7 @@ enum cpuhp_state {
        CPUHP_ARM_BL_PREPARE,
        CPUHP_TRACE_RB_PREPARE,
        CPUHP_MM_ZS_PREPARE,
+       CPUHP_MM_ZSWP_MEM_PREPARE,
        CPUHP_TIMERS_DEAD,
        CPUHP_NOTF_ERR_INJ_PREPARE,
        CPUHP_MIPS_SOC_PREPARE,
diff --git a/mm/zswap.c b/mm/zswap.c
index 275b22c..b13aa57 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -352,70 +352,28 @@ static struct zswap_entry *zswap_entry_find_get(struct 
rb_root *root,
 **********************************/
 static DEFINE_PER_CPU(u8 *, zswap_dstmem);
 
-static int __zswap_cpu_dstmem_notifier(unsigned long action, unsigned long cpu)
+static int zswap_dstmem_prepare(unsigned int cpu)
 {
        u8 *dst;
 
-       switch (action) {
-       case CPU_UP_PREPARE:
-               dst = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
-               if (!dst) {
-                       pr_err("can't allocate compressor buffer\n");
-                       return NOTIFY_BAD;
-               }
-               per_cpu(zswap_dstmem, cpu) = dst;
-               break;
-       case CPU_DEAD:
-       case CPU_UP_CANCELED:
-               dst = per_cpu(zswap_dstmem, cpu);
-               kfree(dst);
-               per_cpu(zswap_dstmem, cpu) = NULL;
-               break;
-       default:
-               break;
+       dst = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
+       if (!dst) {
+               pr_err("can't allocate compressor buffer\n");
+               return -ENOMEM;
        }
-       return NOTIFY_OK;
+       per_cpu(zswap_dstmem, cpu) = dst;
+       return 0;
 }
 
-static int zswap_cpu_dstmem_notifier(struct notifier_block *nb,
-                                    unsigned long action, void *pcpu)
+static int zswap_dstmem_dead(unsigned int cpu)
 {
-       return __zswap_cpu_dstmem_notifier(action, (unsigned long)pcpu);
-}
-
-static struct notifier_block zswap_dstmem_notifier = {
-       .notifier_call =        zswap_cpu_dstmem_notifier,
-};
+       u8 *dst;
 
-static int __init zswap_cpu_dstmem_init(void)
-{
-       unsigned long cpu;
+       dst = per_cpu(zswap_dstmem, cpu);
+       kfree(dst);
+       per_cpu(zswap_dstmem, cpu) = NULL;
 
-       cpu_notifier_register_begin();
-       for_each_online_cpu(cpu)
-               if (__zswap_cpu_dstmem_notifier(CPU_UP_PREPARE, cpu) ==
-                   NOTIFY_BAD)
-                       goto cleanup;
-       __register_cpu_notifier(&zswap_dstmem_notifier);
-       cpu_notifier_register_done();
        return 0;
-
-cleanup:
-       for_each_online_cpu(cpu)
-               __zswap_cpu_dstmem_notifier(CPU_UP_CANCELED, cpu);
-       cpu_notifier_register_done();
-       return -ENOMEM;
-}
-
-static void zswap_cpu_dstmem_destroy(void)
-{
-       unsigned long cpu;
-
-       cpu_notifier_register_begin();
-       for_each_online_cpu(cpu)
-               __zswap_cpu_dstmem_notifier(CPU_UP_CANCELED, cpu);
-       __unregister_cpu_notifier(&zswap_dstmem_notifier);
-       cpu_notifier_register_done();
 }
 
 static int __zswap_cpu_comp_notifier(struct zswap_pool *pool,
@@ -1238,6 +1196,7 @@ static void __exit zswap_debugfs_exit(void) { }
 static int __init init_zswap(void)
 {
        struct zswap_pool *pool;
+       int ret;
 
        zswap_init_started = true;
 
@@ -1246,7 +1205,9 @@ static int __init init_zswap(void)
                goto cache_fail;
        }
 
-       if (zswap_cpu_dstmem_init()) {
+       ret = cpuhp_setup_state(CPUHP_MM_ZSWP_MEM_PREPARE, "mm/zswap:prepare",
+                               zswap_dstmem_prepare, zswap_dstmem_dead);
+       if (ret) {
                pr_err("dstmem alloc failed\n");
                goto dstmem_fail;
        }
@@ -1267,7 +1228,7 @@ static int __init init_zswap(void)
        return 0;
 
 pool_fail:
-       zswap_cpu_dstmem_destroy();
+       cpuhp_remove_state(CPUHP_MM_ZSWP_MEM_PREPARE);
 dstmem_fail:
        zswap_entry_cache_destroy();
 cache_fail:

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