squash! srcu: Create and srcu_read_lock_nmisafe() and srcu_read_unlock_nmisafe()

[ paulmck: Apply feedback from Randy Dunlap. ]

Signed-off-by: Paul E. McKenney <[email protected]>

Author: paulmckrcu

include/linux/srcu.h

@@ -52,6 +52,8 @@ int init_srcu_struct(struct srcu_struct *ssp);
 #else
 /* Dummy definition for things like notifiers.  Actual use gets link error. */
 struct srcu_struct { };
+int __srcu_read_lock_nmisafe(struct srcu_struct *ssp, bool chknmisafe) __acquires(ssp);
+void __srcu_read_unlock_nmisafe(struct srcu_struct *ssp, int idx, bool chknmisafe) __releases(ssp);
 #endif
 
 void call_srcu(struct srcu_struct *ssp, struct rcu_head *head,