Commit-ID: 5bd96ab6fef66ec6b9f54134364e618fd0f8f2f3
Gitweb: http://git.kernel.org/tip/5bd96ab6fef66ec6b9f54134364e618fd0f8f2f3
Author: Oleg Nesterov <oleg@xxxxxxxxxx>
AuthorDate: Sun, 21 Sep 2014 21:33:41 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 24 Sep 2014 14:47:04 +0200
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: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Kirill Tkhai <tkhai@xxxxxxxxx>
Cc: Mike Galbraith <umgwanakikbuti@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20140921193341.GA28628@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/sched/debug.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index c7fe1ea0..ce33780 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -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");
}
--
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