For RCU tasks trace, the userspace execution is also a valid quiescent
state, when scheduling-clock interrupt handler interrupts the task is
in userspace.
if the ->trc_reader_nesting is zero, and the ->trc_reader_special.b.need_qs
is not set, set the tasks ->trc_reader_special.b.need_qs is
TRC_NEED_QS_CHECKED, this cause grace-period kthread remove it from holdout
list if it remains here.
If the ->trc_reader_nesting is not zero(if one of the functions in the
scheduling-clock interrupt handler were traced/instrumented), and starts a
new RCU tasks trace grace period, when grace period kthread scan running
tasks on each CPU, this running uasks will be inserted into hold list.
This commit add rcu_tasks_trace_qs() to rcu_flavor_sched_clock_irq()
when the kernel built with no PREEMPT_RCU.
Signed-off-by: Zqiang <[email protected]>
---
v1->v2:
Fix build error due to undeclared rcu_tasks_trace_qs(), note in no-PREEMPT_RCU
kernel, the RCU Tasks is replaced by RCU, so rcu_note_voluntary_context_switch()
only include rcu_tasks_trace_qs().
v2->v3:
Modify commit information.
kernel/rcu/tree_plugin.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 4152816dd29f..5fb0b2dd24fd 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -976,7 +976,7 @@ static void rcu_flavor_sched_clock_irq(int user)
* neither access nor modify, at least not while the
* corresponding CPU is online.
*/
-
+ rcu_note_voluntary_context_switch(current);
rcu_qs();
}
}
--
2.25.1