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Commit cd4ae6ad authored by Xiaotian Feng's avatar Xiaotian Feng Committed by Ingo Molnar
Browse files

sched: More sched_domain iterations fixes 



sched_domain iterations needs to be protected by rcu_read_lock() now,
this patch adds another two places which needs the rcu lock, which is
spotted by following suspicious rcu_dereference_check() usage warnings.

kernel/sched_rt.c:1244 invoked rcu_dereference_check() without protection!
kernel/sched_stats.h:41 invoked rcu_dereference_check() without protection!

Signed-off-by: default avatarXiaotian Feng <dfeng@redhat.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1303469634-11678-1-git-send-email-dfeng@redhat.com


Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent dc7acbb2

kernel/sched_rt.c

+8 −2
Original line number Diff line number Diff line
@@ -1263,6 +1263,7 @@ static int find_lowest_rq(struct task_struct *task) 
	if (!cpumask_test_cpu(this_cpu, lowest_mask))

		this_cpu = -1; /* Skip this_cpu opt if not among lowest */



	rcu_read_lock();

	for_each_domain(cpu, sd) {

		if (sd->flags & SD_WAKE_AFFINE) {

			int best_cpu;
@@ -1272,15 +1273,20 @@ static int find_lowest_rq(struct task_struct *task) 
			 * remote processor.

			 */

			if (this_cpu != -1 &&

			    cpumask_test_cpu(this_cpu, sched_domain_span(sd)))

			    cpumask_test_cpu(this_cpu, sched_domain_span(sd))) {

				rcu_read_unlock();

				return this_cpu;

			}



			best_cpu = cpumask_first_and(lowest_mask,

						     sched_domain_span(sd));

			if (best_cpu < nr_cpu_ids)

			if (best_cpu < nr_cpu_ids) {

				rcu_read_unlock();

				return best_cpu;

			}

		}

	}

	rcu_read_unlock();



	/*

	 * And finally, if there were no matches within the domains

kernel/sched_stats.h

+2 −2
Original line number Diff line number Diff line
@@ -37,7 +37,7 @@ static int show_schedstat(struct seq_file *seq, void *v) 


#ifdef CONFIG_SMP

		/* domain-specific stats */

		preempt_disable();

		rcu_read_lock();

		for_each_domain(cpu, sd) {

			enum cpu_idle_type itype;
@@ -64,7 +64,7 @@ static int show_schedstat(struct seq_file *seq, void *v) 
			    sd->ttwu_wake_remote, sd->ttwu_move_affine,

			    sd->ttwu_move_balance);

		}

		preempt_enable();

		rcu_read_unlock();

#endif

	}

	kfree(mask_str);