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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2014-08-05 05:10:24 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2014-09-07 16:27:31 -0700
commit8f20a5e83d2c5d0e126a2fc9bca67f7430dac907 (patch)
tree48333b2fd0773d384e5e907401812645fc9575b2 /kernel/rcu/update.c
parent176f8f7a52cc6d09d686f0d900abda6942a52fbb (diff)
downloadlinux-sh-8f20a5e83d2c5d0e126a2fc9bca67f7430dac907.tar.gz
rcu: Make rcu_tasks_kthread()'s GP-wait loop allow preemption
The grace-period-wait loop in rcu_tasks_kthread() is under (unnecessary) RCU protection, and therefore has no preemption points in a PREEMPT=n kernel. This commit therefore removes the RCU protection and inserts cond_resched(). Reported-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcu/update.c')
-rw-r--r--kernel/rcu/update.c11
1 files changed, 6 insertions, 5 deletions
diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 2658de4a5975..f86d1ae50005 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -467,7 +467,7 @@ static void check_holdout_task(struct task_struct *t,
(IS_ENABLED(CONFIG_NO_HZ_FULL) &&
!is_idle_task(t) && t->rcu_tasks_idle_cpu >= 0)) {
ACCESS_ONCE(t->rcu_tasks_holdout) = false;
- list_del_rcu(&t->rcu_tasks_holdout_list);
+ list_del_init(&t->rcu_tasks_holdout_list);
put_task_struct(t);
return;
}
@@ -573,6 +573,7 @@ static int __noreturn rcu_tasks_kthread(void *arg)
bool firstreport;
bool needreport;
int rtst;
+ struct task_struct *t1;
schedule_timeout_interruptible(HZ);
rtst = ACCESS_ONCE(rcu_task_stall_timeout);
@@ -582,11 +583,11 @@ static int __noreturn rcu_tasks_kthread(void *arg)
lastreport = jiffies;
firstreport = true;
WARN_ON(signal_pending(current));
- rcu_read_lock();
- list_for_each_entry_rcu(t, &rcu_tasks_holdouts,
- rcu_tasks_holdout_list)
+ list_for_each_entry_safe(t, t1, &rcu_tasks_holdouts,
+ rcu_tasks_holdout_list) {
check_holdout_task(t, needreport, &firstreport);
- rcu_read_unlock();
+ cond_resched();
+ }
}
/*