[PATCH 2/5] kmod: Use system_unbound_wq instead of khelper

[Frederic Weisbecker <fweisbec@gmail.com>]

We need to launch the usermodehelper kernel threads with the widest
affinity and this is why we have khelper for. This workqueue has unbound
properties and thus a wide affinity inherited by all its children.

Now khelper also has special properties that we aren't much interested
in: ordered and singlethread. There is really no need about ordering as
all we do is creating kernel threads. This can be done concurrently.
And singlethread is a useless limitation as well.

The workqueue engine already proposes generic unbound workqueues that
don't share these useless properties and handle well parallel jobs.

Lets just use them.

Suggested-by: Oleg Nesterov <oleg@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
 include/linux/kmod.h |  2 --
 init/main.c          |  1 -
 kernel/kmod.c        | 12 ++----------
 3 files changed, 2 insertions(+), 13 deletions(-)

diff --git a/include/linux/kmod.h b/include/linux/kmod.h
index 0555cc6..fcfd2bf 100644
--- a/include/linux/kmod.h
+++ b/include/linux/kmod.h
@@ -85,8 +85,6 @@ enum umh_disable_depth {
 	UMH_DISABLED,
 };
 
-extern void usermodehelper_init(void);
-
 extern int __usermodehelper_disable(enum umh_disable_depth depth);
 extern void __usermodehelper_set_disable_depth(enum umh_disable_depth depth);
 
diff --git a/init/main.c b/init/main.c
index c5d5626..45551f8 100644
--- a/init/main.c
+++ b/init/main.c
@@ -877,7 +877,6 @@ static void __init do_initcalls(void)
 static void __init do_basic_setup(void)
 {
 	cpuset_init_smp();
-	usermodehelper_init();
 	shmem_init();
 	driver_init();
 	init_irq_proc();
diff --git a/kernel/kmod.c b/kernel/kmod.c
index 4682e91..d8cc116ab 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -45,8 +45,6 @@
 
 extern int max_threads;
 
-static struct workqueue_struct *khelper_wq;
-
 #define CAP_BSET	(void *)1
 #define CAP_PI		(void *)2
 
@@ -548,7 +546,7 @@ int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait)
 		return -EINVAL;
 	}
 	helper_lock();
-	if (!khelper_wq || usermodehelper_disabled) {
+	if (usermodehelper_disabled) {
 		retval = -EBUSY;
 		goto out;
 	}
@@ -560,7 +558,7 @@ int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait)
 	sub_info->complete = (wait == UMH_NO_WAIT) ? NULL : &done;
 	sub_info->wait = wait;
 
-	queue_work(khelper_wq, &sub_info->work);
+	queue_work(system_unbound_wq, &sub_info->work);
 	if (wait == UMH_NO_WAIT)	/* task has freed sub_info */
 		goto unlock;
 
@@ -690,9 +688,3 @@ struct ctl_table usermodehelper_table[] = {
 	},
 	{ }
 };
-
-void __init usermodehelper_init(void)
-{
-	khelper_wq = create_singlethread_workqueue("khelper");
-	BUG_ON(!khelper_wq);
-}
-- 
2.1.4