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/rcupdate.h b/include/linux/rcupdate.h
index a0189ba..f2b667d 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -379,9 +379,9 @@
*/
#define RCU_NONIDLE(a) \
do { \
- rcu_irq_enter(); \
+ rcu_irq_enter_irqson(); \
do { a; } while (0); \
- rcu_irq_exit(); \
+ rcu_irq_exit_irqson(); \
} while (0)
/*