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authorLinus Torvalds <torvalds@linux-foundation.org>2009-04-08 18:00:55 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-04-08 18:00:55 -0700
commitf4efdd65b754ebbf41484d3a2255c59282720650 (patch)
tree3133af9efc0819b9bae0af52276c2e259c1e63cb
parentd8312204768861d77ec868265b2c1a36a1bf078f (diff)
parent6b44003e5ca66a3fffeb5bc90f40ada2c4340896 (diff)
Merge git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus
* git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus: work_on_cpu(): rewrite it to create a kernel thread on demand kthread: move sched-realeted initialization from kthreadd context kthread: Don't looking for a task in create_kthread() #2
-rw-r--r--kernel/kthread.c26
-rw-r--r--kernel/workqueue.c36
2 files changed, 31 insertions, 31 deletions
diff --git a/kernel/kthread.c b/kernel/kthread.c
index 84bbadd4d02..4ebaf8519ab 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -76,6 +76,7 @@ static int kthread(void *_create)
/* OK, tell user we're spawned, wait for stop or wakeup */
__set_current_state(TASK_UNINTERRUPTIBLE);
+ create->result = current;
complete(&create->started);
schedule();
@@ -96,22 +97,10 @@ static void create_kthread(struct kthread_create_info *create)
/* We want our own signal handler (we take no signals by default). */
pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD);
- if (pid < 0) {
+ if (pid < 0)
create->result = ERR_PTR(pid);
- } else {
- struct sched_param param = { .sched_priority = 0 };
+ else
wait_for_completion(&create->started);
- read_lock(&tasklist_lock);
- create->result = find_task_by_pid_ns(pid, &init_pid_ns);
- read_unlock(&tasklist_lock);
- /*
- * root may have changed our (kthreadd's) priority or CPU mask.
- * The kernel thread should not inherit these properties.
- */
- sched_setscheduler(create->result, SCHED_NORMAL, &param);
- set_user_nice(create->result, KTHREAD_NICE_LEVEL);
- set_cpus_allowed_ptr(create->result, cpu_all_mask);
- }
complete(&create->done);
}
@@ -154,11 +143,20 @@ struct task_struct *kthread_create(int (*threadfn)(void *data),
wait_for_completion(&create.done);
if (!IS_ERR(create.result)) {
+ struct sched_param param = { .sched_priority = 0 };
va_list args;
+
va_start(args, namefmt);
vsnprintf(create.result->comm, sizeof(create.result->comm),
namefmt, args);
va_end(args);
+ /*
+ * root may have changed our (kthreadd's) priority or CPU mask.
+ * The kernel thread should not inherit these properties.
+ */
+ sched_setscheduler_nocheck(create.result, SCHED_NORMAL, &param);
+ set_user_nice(create.result, KTHREAD_NICE_LEVEL);
+ set_cpus_allowed_ptr(create.result, cpu_all_mask);
}
return create.result;
}
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index b6b966ce145..f71fb2a0895 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -966,20 +966,20 @@ undo:
}
#ifdef CONFIG_SMP
-static struct workqueue_struct *work_on_cpu_wq __read_mostly;
struct work_for_cpu {
- struct work_struct work;
+ struct completion completion;
long (*fn)(void *);
void *arg;
long ret;
};
-static void do_work_for_cpu(struct work_struct *w)
+static int do_work_for_cpu(void *_wfc)
{
- struct work_for_cpu *wfc = container_of(w, struct work_for_cpu, work);
-
+ struct work_for_cpu *wfc = _wfc;
wfc->ret = wfc->fn(wfc->arg);
+ complete(&wfc->completion);
+ return 0;
}
/**
@@ -990,17 +990,23 @@ static void do_work_for_cpu(struct work_struct *w)
*
* This will return the value @fn returns.
* It is up to the caller to ensure that the cpu doesn't go offline.
+ * The caller must not hold any locks which would prevent @fn from completing.
*/
long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)
{
- struct work_for_cpu wfc;
-
- INIT_WORK(&wfc.work, do_work_for_cpu);
- wfc.fn = fn;
- wfc.arg = arg;
- queue_work_on(cpu, work_on_cpu_wq, &wfc.work);
- flush_work(&wfc.work);
-
+ struct task_struct *sub_thread;
+ struct work_for_cpu wfc = {
+ .completion = COMPLETION_INITIALIZER_ONSTACK(wfc.completion),
+ .fn = fn,
+ .arg = arg,
+ };
+
+ sub_thread = kthread_create(do_work_for_cpu, &wfc, "work_for_cpu");
+ if (IS_ERR(sub_thread))
+ return PTR_ERR(sub_thread);
+ kthread_bind(sub_thread, cpu);
+ wake_up_process(sub_thread);
+ wait_for_completion(&wfc.completion);
return wfc.ret;
}
EXPORT_SYMBOL_GPL(work_on_cpu);
@@ -1016,8 +1022,4 @@ void __init init_workqueues(void)
hotcpu_notifier(workqueue_cpu_callback, 0);
keventd_wq = create_workqueue("events");
BUG_ON(!keventd_wq);
-#ifdef CONFIG_SMP
- work_on_cpu_wq = create_workqueue("work_on_cpu");
- BUG_ON(!work_on_cpu_wq);
-#endif
}