Commit-ID: a0ef9ec24144799b5b47fa54c38f9a0f9dfe9a59
Gitweb: https://git.kernel.org/tip/a0ef9ec24144799b5b47fa54c38f9a0f9dfe9a59
Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
AuthorDate: Mon, 9 Jul 2018 15:50:16 -0700
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Thu, 30 Aug 2018 16:03:39 -0700
rcu: Provide improved interrupt-from-idle check in rcu_check_callbacks()
The patch making need_resched() respond to urgent RCU-QS needs used
is_idle_task(current) to detect an interrupt from idle, which does work
reasonably, but is (in theory at least) vulnerable to loops containing
need_resched() invoked from within RCU_NONIDLE() or its tracepoint
equivalent. This commit therefore moves rcu_is_cpu_rrupt_from_idle()
to a place from which rcu_check_callbacks() can invoke it and replaces
the is_idle_task(current) with rcu_is_cpu_rrupt_from_idle().
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
kernel/rcu/tree.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index f47ac7a4719f..77d2cbf7c831 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2474,7 +2474,7 @@ void rcu_check_callbacks(int user)
/* The load-acquire pairs with the store-release setting to true. */
if (smp_load_acquire(this_cpu_ptr(&rcu_dynticks.rcu_urgent_qs))) {
/* Idle and userspace execution already are quiescent states. */
- if (!is_idle_task(current) && !user) {
+ if (!rcu_is_cpu_rrupt_from_idle() && !user) {
set_tsk_need_resched(current);
set_preempt_need_resched();
}
|