rcu: Don't redundantly disable irqs in rcu_irq_{enter,exit}()
This commit replaces a local_irq_save()/local_irq_restore() pair with
a lockdep assertion that interrupts are already disabled. This should
remove the corresponding overhead from the interrupt entry/exit fastpaths.
This change was inspired by the fact that Iftekhar Ahmed's mutation
testing showed that removing rcu_irq_enter()'s call to local_ird_restore()
had no effect, which might indicate that interrupts were always enabled
anyway.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index 9d3eda3..ad1eda9 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -97,6 +97,8 @@
void rcu_idle_exit(void);
void rcu_irq_enter(void);
void rcu_irq_exit(void);
+void rcu_irq_enter_irqson(void);
+void rcu_irq_exit_irqson(void);
void exit_rcu(void);