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 | 11 ++++-------
1 file changed, 4 insertions(+), 7 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
@@ -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 kthrea
/* 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 (
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
linux-next.patch
slow_work_thread-should-do-the-exclusive-wait.patch
rework-fix-is_single_threaded.patch
getrusage-fill-ru_maxrss-value.patch
ptrace-remove-pt_dtrace-from-arch-h8300.patch
ptrace-remove-pt_dtrace-from-avr32-mn10300-parisc-s390-sh-xtensa.patch
ptrace-remove-pt_dtrace-from-m68k-m68knommu.patch
ptrace-remove-pt_dtrace-from-arch-m32r.patch
ptrace-mm_need_new_owner-use-real_parent-to-search-in-the-siblings.patch
ptrace-tracehook_unsafe_exec-remove-the-stale-comment.patch
ptrace-tracehook_unsafe_exec-remove-the-stale-comment-fix.patch
copy_process-remove-the-unneeded-clear_tsk_thread_flagtif_sigpending.patch
kthreads-simplify-the-startup-synchronization.patch
kthreads-rework-kthread_stop.patch
kthreads-simplify-migration_thread-exit-path.patch
signals-split-do_tkill.patch
signals-implement-sys_rt_tgsigqueueinfo.patch
x86-hookup-sys_rt_tgsigqueueinfo.patch
signals-tracehook_notify_jctl-change.patch
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