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| author | Oleg Nesterov <oleg@redhat.com> | 2013-04-30 02:05:12 +0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-04-30 02:54:25 +0400 |
| commit | b5c5442bb6bce0c67701d55124be561043a51faf (patch) | |
| tree | f00a0fdcdb157fa4b8f54c6a31d3935b7c927aa6 /kernel/kthread.c | |
| parent | 4ecdafc8084fe1d95bb59ed7753b345abcd586fb (diff) | |
| download | linux-b5c5442bb6bce0c67701d55124be561043a51faf.tar.xz | |
kthread: kill task_get_live_kthread()
task_get_live_kthread() looks confusing and unneeded. It does
get_task_struct() but only kthread_stop() needs this, it can be called
even if the calller doesn't have a reference when we know that this
kthread can't exit until we do kthread_stop().
kthread_park() and kthread_unpark() do not need get_task_struct(), the
callers already have the reference. And it can not help if we can race
with the exiting kthread anyway, kthread_park() can hang forever in this
case.
Change kthread_park() and kthread_unpark() to use to_live_kthread(),
change kthread_stop() to do get_task_struct() by hand and remove
task_get_live_kthread().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/kthread.c')
| -rw-r--r-- | kernel/kthread.c | 20 |
1 files changed, 7 insertions, 13 deletions
diff --git a/kernel/kthread.c b/kernel/kthread.c index a84dee265f94..9b12d65186f7 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -324,12 +324,6 @@ struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data), return p; } -static struct kthread *task_get_live_kthread(struct task_struct *k) -{ - get_task_struct(k); - return to_live_kthread(k); -} - static void __kthread_unpark(struct task_struct *k, struct kthread *kthread) { clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags); @@ -356,11 +350,10 @@ static void __kthread_unpark(struct task_struct *k, struct kthread *kthread) */ void kthread_unpark(struct task_struct *k) { - struct kthread *kthread = task_get_live_kthread(k); + struct kthread *kthread = to_live_kthread(k); if (kthread) __kthread_unpark(k, kthread); - put_task_struct(k); } /** @@ -377,7 +370,7 @@ void kthread_unpark(struct task_struct *k) */ int kthread_park(struct task_struct *k) { - struct kthread *kthread = task_get_live_kthread(k); + struct kthread *kthread = to_live_kthread(k); int ret = -ENOSYS; if (kthread) { @@ -390,7 +383,6 @@ int kthread_park(struct task_struct *k) } ret = 0; } - put_task_struct(k); return ret; } @@ -411,10 +403,13 @@ int kthread_park(struct task_struct *k) */ int kthread_stop(struct task_struct *k) { - struct kthread *kthread = task_get_live_kthread(k); + struct kthread *kthread; int ret; trace_sched_kthread_stop(k); + + get_task_struct(k); + kthread = to_live_kthread(k); if (kthread) { set_bit(KTHREAD_SHOULD_STOP, &kthread->flags); __kthread_unpark(k, kthread); @@ -422,10 +417,9 @@ int kthread_stop(struct task_struct *k) wait_for_completion(&kthread->exited); } ret = k->exit_code; - put_task_struct(k); - trace_sched_kthread_stop_ret(ret); + trace_sched_kthread_stop_ret(ret); return ret; } EXPORT_SYMBOL(kthread_stop); |