From: Paul E. McKenney <paulmck@kernel.org>
Date: Mon, 16 Mar 2020 22:22:44 +0000 (-0700)
Subject: rcu-tasks: Use context-switch hook for PREEMPT=y kernels
X-Git-Tag: block-5.8-2020-06-11~54^2~17^2^3~35
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=66777e5821f6e672003fde697b8489402bb5aa98;p=linux-2.6-block.git

rcu-tasks: Use context-switch hook for PREEMPT=y kernels

Currently, the PREEMPT=y version of rcu_note_context_switch() does not
invoke rcu_tasks_qs(), and we need it to in order to keep RCU Tasks
Trace's IPIs down to a dull roar.  This commit therefore enables this
hook.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---

diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 088e84e4578f..4f34c325dd90 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -331,6 +331,8 @@ void rcu_note_context_switch(bool preempt)
 	rcu_qs();
 	if (rdp->exp_deferred_qs)
 		rcu_report_exp_rdp(rdp);
+	if (!preempt)
+		rcu_tasks_qs(current);
 	trace_rcu_utilization(TPS("End context switch"));
 }
 EXPORT_SYMBOL_GPL(rcu_note_context_switch);