On (11/13/14 21:37), Mahendran Ganesh wrote:
> Now zsmalloc can be registered as a zpool driver into zpool when
> CONFIG_ZPOOL is enabled. During the init of zsmalloc, when error happens,
> we need to do cleanup. But in current code, it will unregister a not yet
> registered zsmalloc zpool driver(*zs_zpool_driver*).
> 
> This patch puts the cleanup in zs_init() instead of calling zs_exit()
> where it will unregister a not-registered zpool driver.
> 
> Signed-off-by: Mahendran Ganesh <opensource.gan...@gmail.com>
> ---
>  mm/zsmalloc.c |   12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> index 839a48c..3d2bb36 100644
> --- a/mm/zsmalloc.c
> +++ b/mm/zsmalloc.c
> @@ -907,10 +907,8 @@ static int zs_init(void)
>       __register_cpu_notifier(&zs_cpu_nb);
>       for_each_online_cpu(cpu) {
>               ret = zs_cpu_notifier(NULL, CPU_UP_PREPARE, (void *)(long)cpu);
> -             if (notifier_to_errno(ret)) {
> -                     cpu_notifier_register_done();
> +             if (notifier_to_errno(ret))
>                       goto fail;
> -             }
>       }
>  
>       cpu_notifier_register_done();
> @@ -920,8 +918,14 @@ static int zs_init(void)
>  #endif
>  
>       return 0;
> +
>  fail:
> -     zs_exit();
> +     for_each_online_cpu(cpu)
> +             zs_cpu_notifier(NULL, CPU_UP_CANCELED, (void *)(long)cpu);
> +     __unregister_cpu_notifier(&zs_cpu_nb);
> +
> +     cpu_notifier_register_done();
> +
>       return notifier_to_errno(ret);

so we duplicate same code, and there is a bit confusing part
now: zs_cpu_notifier(CPU_UP_CANCELED) and zs_cpu_notifier(CPU_DEAD)
calls.


how about something like this?

Factor out zsmalloc cpu notifier unregistration code and call
it from both zs_exit() and zs_init() error path.

Signed-off-by: Sergey Senozhatsky <sergey.senozhat...@gmail.com>

---

 mm/zsmalloc.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index b3b57ef..c4d2d60 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -881,14 +881,10 @@ static struct notifier_block zs_cpu_nb = {
        .notifier_call = zs_cpu_notifier
 };
 
-static void zs_exit(void)
+static inline void zs_unregister_cpu_notifier()
 {
        int cpu;
 
-#ifdef CONFIG_ZPOOL
-       zpool_unregister_driver(&zs_zpool_driver);
-#endif
-
        cpu_notifier_register_begin();
 
        for_each_online_cpu(cpu)
@@ -898,6 +894,14 @@ static void zs_exit(void)
        cpu_notifier_register_done();
 }
 
+static void zs_exit(void)
+{
+#ifdef CONFIG_ZPOOL
+       zpool_unregister_driver(&zs_zpool_driver);
+#endif
+       zs_unregister_cpu_notifier();
+}
+
 static int zs_init(void)
 {
        int cpu, ret;
@@ -907,10 +911,8 @@ static int zs_init(void)
        __register_cpu_notifier(&zs_cpu_nb);
        for_each_online_cpu(cpu) {
                ret = zs_cpu_notifier(NULL, CPU_UP_PREPARE, (void *)(long)cpu);
-               if (notifier_to_errno(ret)) {
-                       cpu_notifier_register_done();
+               if (notifier_to_errno(ret))
                        goto fail;
-               }
        }
 
        cpu_notifier_register_done();
@@ -921,7 +923,7 @@ static int zs_init(void)
 
        return 0;
 fail:
-       zs_exit();
+       zs_unregister_cpu_notifier();
        return notifier_to_errno(ret);
 }
 
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