rcu: Switch task's syscall hooks on context switch
Clear the syscalls hook of a task when it's scheduled out so that if
the task migrates, it doesn't run the syscall slow path on a CPU
that might not need it.
Also set the syscalls hook on the next task if needed.
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/kernel/rcutree.c b/kernel/rcutree.c
index 6b82a95..d2e74c8 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -717,6 +717,21 @@
}
EXPORT_SYMBOL(rcu_is_cpu_idle);
+#ifdef CONFIG_RCU_USER_QS
+void rcu_user_hooks_switch(struct task_struct *prev,
+ struct task_struct *next)
+{
+ struct rcu_dynticks *rdtp;
+
+ /* Interrupts are disabled in context switch */
+ rdtp = &__get_cpu_var(rcu_dynticks);
+ if (!rdtp->ignore_user_qs) {
+ clear_tsk_thread_flag(prev, TIF_NOHZ);
+ set_tsk_thread_flag(next, TIF_NOHZ);
+ }
+}
+#endif /* #ifdef CONFIG_RCU_USER_QS */
+
#if defined(CONFIG_PROVE_RCU) && defined(CONFIG_HOTPLUG_CPU)
/*
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 1a48cdb..ea2213b 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2081,6 +2081,7 @@
#endif
/* Here we just switch the register state and the stack. */
+ rcu_switch(prev, next);
switch_to(prev, next, prev);
barrier();