rcu: Userspace RCU extended QS selftest

Provide a config option that enables the userspace
RCU extended quiescent state on every CPUs by default.

This is for testing purpose.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Alessio Igor Bogani <abogani@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Avi Kivity <avi@redhat.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Kevin Hilman <khilman@ti.com>
Cc: Max Krasnyansky <maxk@qualcomm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Hemminger <shemminger@vyatta.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Sven-Thorsten Dietrich <thebigcorporation@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>

diff --git a/init/Kconfig b/init/Kconfig
index f6a1830165cea833dd5e674e14fefad4ec5469a3..c26b8a1d2b576f8b0286168bbed0647a7ded67a1 100644 (file)
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -451,6 +451,14 @@ config RCU_USER_QS
          excluded from the global RCU state machine and thus doesn't
          to keep the timer tick on for RCU.
 
+config RCU_USER_QS_FORCE
+       bool "Force userspace extended QS by default"
+       depends on RCU_USER_QS
+       help
+         Set the hooks in user/kernel boundaries by default in order to
+         test this feature that treats userspace as an extended quiescent
+         state until we have a real user like a full adaptive nohz option.
+
 config RCU_FANOUT
        int "Tree-based hierarchical RCU fanout value"
        range 2 64 if 64BIT

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index d2e74c8d4b0e5330d1f4f422cf876041f70688bb..812d04b6b395055a7298dae5b59f525a92634d76 100644 (file)
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -206,7 +206,7 @@ EXPORT_SYMBOL_GPL(rcu_note_context_switch);
 DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = {
        .dynticks_nesting = DYNTICK_TASK_EXIT_IDLE,
        .dynticks = ATOMIC_INIT(1),
-#ifdef CONFIG_RCU_USER_QS
+#if defined(CONFIG_RCU_USER_QS) && !defined(CONFIG_RCU_USER_QS_FORCE)
        .ignore_user_qs = true,
 #endif
 };