From cdd140bdd6c7bc6395f08877a73c39941501af93 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Wed, 17 Jun 2009 16:27:43 -0700 Subject: [PATCH] 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 Cc: Christoph Hellwig Cc: "Eric W. Biederman" Cc: Ingo Molnar Cc: Pavel Emelyanov Cc: Rusty Russell Cc: Vitaliy Gusev Signed-off-by: Linus Torvalds --- kernel/kthread.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) diff --git a/kernel/kthread.c b/kernel/kthread.c index 7fa441333529..bc5d1f0b25a4 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); -- 2.30.2