The patch titled
kthreads: simplify the startup synchronization
has been added to the -mm tree. Its filename is
kthreads-simplify-the-startup-synchronization.patch
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------------------------------------------------------
Subject: kthreads: simplify the startup synchronization
From: Oleg Nesterov <oleg@xxxxxxxxxx>
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@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxx>
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Vitaliy Gusev <vgusev@xxxxxxxxxx
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/kthread.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)
diff -puN kernel/kthread.c~kthreads-simplify-the-startup-synchronization kernel/kthread.c
--- a/kernel/kthread.c~kthreads-simplify-the-startup-synchronization
+++ a/kernel/kthread.c
@@ -31,7 +31,6 @@ 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;
@@ -79,7 +78,7 @@ 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())
@@ -101,10 +100,8 @@ static void create_kthread(struct kthrea
pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD);
if (pid < 0) {
create->result = ERR_PTR(pid);
- } else {
- wait_for_completion(&create->started);
+ complete(&create->done);
}
- complete(&create->done);
}
/**
@@ -135,7 +132,6 @@ struct task_struct *kthread_create(int (
create.threadfn = threadfn;
create.data = data;
- init_completion(&create.started);
init_completion(&create.done);
spin_lock(&kthread_create_lock);
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
origin.patch
wait-prevent-exclusive-waiter-starvation.patch
linux-next.patch
pipe_rdwr_fasync-fix-the-error-handling-to-prevent-the-leak-crash.patch
get_mm_hiwater_xxx-trivial-s-define-inline.patch
getrusage-fill-ru_maxrss-value.patch
ptrace-kill-__ptrace_detach-fix-exit_state-check.patch
ptrace-simplify-ptrace_exit-ignoring_children-path.patch
ptrace-simplify-ptrace_exit-ignoring_children-pathpatch-fix.patch
ptrace-reintroduce-__ptrace_detach-as-a-callee-of-ptrace_exit.patch
ptrace-reintroduce-__ptrace_detach-as-a-callee-of-ptrace_exit-fix.patch
ptrace-fix-possible-zombie-leak-on-ptrace_detach.patch
reparent_thread-dont-call-kill_orphaned_pgrp-if-task_detached.patch
reparent_thread-fix-the-is-it-traced-check.patch
reparent_thread-fix-a-zombie-leak-if-sbin-init-ignores-sigchld.patch
forget_original_parent-cleanup-ptrace-pathes.patch
kthread-dont-looking-for-a-task-in-create_kthread-2.patch
kthreads-move-sched-realeted-initialization-from-kthreadd-context.patch
kthreads-simplify-the-startup-synchronization.patch
kthreads-rework-kthread_stop.patch
kthreads-simplify-migration_thread-exit-path.patch
pids-document-task_pgrp-task_session-is-not-safe-without-tasklist-rcu.patch
pids-document-task_pgrp-task_session-is-not-safe-without-tasklist-rcu-fix.patch
pids-improve-get_task_pid-to-fix-the-unsafe-sys_wait4-task_pgrp.patch
pids-refactor-vnr-nr_ns-helpers-to-make-them-safe.patch
pids-kill-now-unused-signal_struct-__pgrp-__session-and-friends.patch
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