rcu: Convert WARN_ON_ONCE() in rcu_lock_acquire() to lockdep

The WARN_ON_ONCE() in rcu_lock_acquire() results in infinite recursion
on S390, and also doesn't print very much information.  Remove this.

Updated patch to add lockdep-RCU assertions to RCU's read-side primitives.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index 9a323728e60c..d3d5fa54f25e 100644
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -172,6 +172,8 @@ static inline int srcu_read_lock(struct srcu_struct *sp) __acquires(sp)
         int retval = __srcu_read_lock(sp);
 
         rcu_lock_acquire(&(sp)->dep_map);
+        rcu_lockdep_assert(!rcu_is_cpu_idle(),
+                           "srcu_read_lock() used illegally while idle");
         return retval;
 }
 
@@ -185,6 +187,8 @@ static inline int srcu_read_lock(struct srcu_struct *sp) __acquires(sp)
 static inline void srcu_read_unlock(struct srcu_struct *sp, int idx)
         __releases(sp)
 {
+        rcu_lockdep_assert(!rcu_is_cpu_idle(),
+                           "srcu_read_unlock() used illegally while idle");
         rcu_lock_release(&(sp)->dep_map);
         __srcu_read_unlock(sp, idx);
 }