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>

1 files changed, 2 insertions, 2 deletions

diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 696a339c592c..7834a8a8bf1e 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -171,8 +171,8 @@ extern void syscall_unregfunc(void);
                                 TP_PROTO(data_proto),                   \
                                 TP_ARGS(data_args),                     \
                                 TP_CONDITION(cond),                     \
-                                rcu_irq_enter(),                        \
-                                rcu_irq_exit());                        \
+                                rcu_irq_enter_irqson(),                 \
+                                rcu_irq_exit_irqson());                 \
         }
 #else
 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)