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authorOleg Nesterov <oleg@redhat.com>2009-06-17 19:27:43 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2009-06-18 16:03:53 -0400
commitcdd140bdd6c7bc6395f08877a73c39941501af93 (patch)
tree48664b2790fb2b5152bd67bf70fb3405e1ef6e8b /kernel
parente1eb1ebcca871673c76caf63335c4237680040f1 (diff)
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 7fa441333529..bc5d1f0b25a4 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -27,7 +27,6 @@ struct kthread_create_info
27 /* Information passed to kthread() from kthreadd. */ 27 /* Information passed to kthread() from kthreadd. */
28 int (*threadfn)(void *data); 28 int (*threadfn)(void *data);
29 void *data; 29 void *data;
30 struct completion started;
31 30
32 /* Result passed back to kthread_create() from kthreadd. */ 31 /* Result passed back to kthread_create() from kthreadd. */
33 struct task_struct *result; 32 struct task_struct *result;
@@ -75,7 +74,7 @@ static int kthread(void *_create)
75 /* OK, tell user we're spawned, wait for stop or wakeup */ 74 /* OK, tell user we're spawned, wait for stop or wakeup */
76 __set_current_state(TASK_UNINTERRUPTIBLE); 75 __set_current_state(TASK_UNINTERRUPTIBLE);
77 create->result = current; 76 create->result = current;
78 complete(&create->started); 77 complete(&create->done);
79 schedule(); 78 schedule();
80 79
81 if (!kthread_should_stop()) 80 if (!kthread_should_stop())
@@ -95,11 +94,10 @@ static void create_kthread(struct kthread_create_info *create)
95 94
96 /* We want our own signal handler (we take no signals by default). */ 95 /* We want our own signal handler (we take no signals by default). */
97 pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD); 96 pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD);
98 if (pid < 0) 97 if (pid < 0) {
99 create->result = ERR_PTR(pid); 98 create->result = ERR_PTR(pid);
100 else 99 complete(&create->done);
101 wait_for_completion(&create->started); 100 }
102 complete(&create->done);
103} 101}
104 102
105/** 103/**
@@ -130,7 +128,6 @@ struct task_struct *kthread_create(int (*threadfn)(void *data),
130 128
131 create.threadfn = threadfn; 129 create.threadfn = threadfn;
132 create.data = data; 130 create.data = data;
133 init_completion(&create.started);
134 init_completion(&create.done); 131 init_completion(&create.done);
135 132
136 spin_lock(&kthread_create_lock); 133 spin_lock(&kthread_create_lock);