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Commit 0cdc29e2 authored by Lingutla Chandrasekhar's avatar Lingutla Chandrasekhar Committed by Gerrit - the friendly Code Review server
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sched: rt: Use RCU lock in rt task cpu select path 



RT energy aware cpu selection tries to get cpu idle state
without holding rcu read lock, it may get stale/corrupted value.

Fix it by moving rcu unlock to end for energy aware cpu
selection.

Change-Id: Ia219062db6b97b9a44681647cea077c45c29cff2
Signed-off-by: default avatarLingutla Chandrasekhar <clingutla@codeaurora.org>
parent 071be09f

kernel/sched/rt.c

+2 −1
Original line number Diff line number Diff line
@@ -1805,7 +1805,6 @@ static int find_lowest_rq(struct task_struct *task) 
				}

			}

		} while (sg = sg->next, sg != sd->groups);

		rcu_read_unlock();



		if (sg_target) {

			cpumask_and(&search_cpu, lowest_mask,
@@ -1894,6 +1893,7 @@ static int find_lowest_rq(struct task_struct *task) 
		}



		if (best_cpu != -1 && placement_boost != SCHED_BOOST_ON_ALL) {

			rcu_read_unlock();

			return best_cpu;

		} else if (!cpumask_empty(&backup_search_cpu)) {

			cpumask_copy(&search_cpu, &backup_search_cpu);
@@ -1902,6 +1902,7 @@ static int find_lowest_rq(struct task_struct *task) 
			placement_boost = SCHED_BOOST_NONE;

			goto retry;

		}

		rcu_read_unlock();

	}



noea: