From b7013589d0ba53392d4a1b77873e20a2056b8793 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Sun, 21 Sep 2014 21:33:41 +0200 Subject: 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(). Change-Id: Iadf0de148e27623af4535abc40c77c1dfd1f9c76 Signed-off-by: Oleg Nesterov Signed-off-by: Peter Zijlstra (Intel) Cc: Kirill Tkhai Cc: Mike Galbraith Cc: Linus Torvalds Link: http://lkml.kernel.org/r/20140921193341.GA28628@redhat.com Signed-off-by: Ingo Molnar --- kernel/sched/debug.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) (limited to 'kernel') diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index 2dad25a3d..4d03fc426 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -188,7 +188,6 @@ 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" @@ -197,14 +196,14 @@ 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 (!p->on_rq || 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) @@ -370,9 +369,7 @@ 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"); } -- cgit v1.2.3