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Commit 5bd96ab6 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Ingo Molnar
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sched: print_rq(): Don't use tasklist_lock 



read_lock_irqsave(tasklist_lock) in print_rq() looks strange. We do
not need to disable irqs, and they are already disabled by the caller.

And afaics this lock buys nothing, we can rely on rcu_read_lock().
In this case it makes sense to also move rcu_read_lock/unlock from
the caller to print_rq().

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140921193341.GA28628@redhat.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 3472eaa1

kernel/sched/debug.c

+2 −5
Original line number Diff line number Diff line
@@ -150,7 +150,6 @@ print_task(struct seq_file *m, struct rq *rq, struct task_struct *p) 
static void print_rq(struct seq_file *m, struct rq *rq, int rq_cpu)

{

	struct task_struct *g, *p;

	unsigned long flags;



	SEQ_printf(m,

	"\nrunnable tasks:\n"
@@ -159,14 +158,14 @@ static void print_rq(struct seq_file *m, struct rq *rq, int rq_cpu) 
	"------------------------------------------------------"

	"----------------------------------------------------\n");



	read_lock_irqsave(&tasklist_lock, flags);

	rcu_read_lock();

	for_each_process_thread(g, p) {

		if (task_cpu(p) != rq_cpu)

			continue;



		print_task(m, rq, p);

	}

	read_unlock_irqrestore(&tasklist_lock, flags);

	rcu_read_unlock();

}



void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)
@@ -331,9 +330,7 @@ do { \ 
	print_cfs_stats(m, cpu);

	print_rt_stats(m, cpu);



	rcu_read_lock();

	print_rq(m, rq, cpu);

	rcu_read_unlock();

	spin_unlock_irqrestore(&sched_debug_lock, flags);

	SEQ_printf(m, "\n");

}