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authorOleg Nesterov <oleg@redhat.com>2009-06-17 16:27:43 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-06-18 13:03:53 -0700
commitcdd140bdd6c7bc6395f08877a73c39941501af93 (patch)
tree48664b2790fb2b5152bd67bf70fb3405e1ef6e8b /kernel
parente1eb1ebcca871673c76caf63335c4237680040f1 (diff)
downloadlinux-2.6.34-ux500-cdd140bdd6c7bc6395f08877a73c39941501af93.tar.gz
kthreads: simplify the startup synchronization
We use two completions two create the kernel thread, this is a bit ugly. kthread() wakes up create_kthread() via ->started, then create_kthread() wakes up the caller kthread_create() via ->done. But kthread() does not need to wait for kthread(), it can just return. Instead kthread() itself can wake up the caller of kthread_create(). Kill kthread_create_info->started, ->done is enough. This improves the scalability a bit and sijmplifies the code. The only problem if kernel_thread() fails, in that case create_kthread() must do complete(&create->done). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Vitaliy Gusev <vgusev@openvz.org Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/kthread.c11
1 files changed, 4 insertions, 7 deletions
diff --git a/kernel/kthread.c b/kernel/kthread.c
index 7fa44133352..bc5d1f0b25a 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -27,7 +27,6 @@ struct kthread_create_info
/* Information passed to kthread() from kthreadd. */
int (*threadfn)(void *data);
void *data;
- struct completion started;
/* Result passed back to kthread_create() from kthreadd. */
struct task_struct *result;
@@ -75,7 +74,7 @@ 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);
+ complete(&create->done);
schedule();
if (!kthread_should_stop())
@@ -95,11 +94,10 @@ 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
- wait_for_completion(&create->started);
- complete(&create->done);
+ complete(&create->done);
+ }
}
/**
@@ -130,7 +128,6 @@ struct task_struct *kthread_create(int (*threadfn)(void *data),
create.threadfn = threadfn;
create.data = data;
- init_completion(&create.started);
init_completion(&create.done);
spin_lock(&kthread_create_lock);