Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull RCU updates from Thomas Gleixner:
 "A large update to RCU:

  Preparatory work for consolidating the RCU flavors:

   - Introduce grace-period sequence numbers to the RCU-bh, RCU-preempt,
     and RCU-sched flavors, replacing the old ->gpnum and ->completed
     pair of fields.

     This change allows lockless code to obtain the complete
     grace-period state with a single READ_ONCE(), which is needed to
     maintain tolerable lock contention during the upcoming
     consolidation of the three RCU flavors.

     Note that grace-period sequence numbers are already used by
     rcu_barrier(), expedited RCU grace periods, and SRCU, and are thus
     already heavily used and well-tested. Joel Fernandes contributed a
     number of excellent fixes and improvements.

   - Clean up some grace-period-reporting loose ends, including
     improving the handling of quiescent states from offline CPUs and
     fixing some false-positive WARN_ON_ONCE() invocations.

     (Strictly speaking, the WARN_ON_ONCE() invocations were quite
     correct, but their invariants were (harmlessly) violated by the
     earlier sloppy handling of quiescent states from offline CPUs.)

     In addition, improve grace-period forward-progress guarantees so as
     to allow removal of fail-safe checks that required otherwise
     needless lock acquisitions. Finally, add more diagnostics to help
     debug the upcoming consolidation of the RCU-bh, RCU-preempt, and
     RCU-sched flavors.

  The rest:

   - SRCU updates

   - Updates to rcutorture and associated scripting.

   - The usual pile of miscellaneous fixes"

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (118 commits)
  rcutorture: Fix rcu_barrier successes counter
  rcutorture: Add support to detect if boost kthread prio is too low
  rcutorture: Use monotonic timestamp for stall detection
  rcutorture: Make boost test more robust
  rcutorture: Disable RT throttling for boost tests
  rcutorture: Emphasize testing of single reader protection type
  rcutorture: Handle extended read-side critical sections
  rcutorture: Make rcu_torture_timer() use rcu_torture_one_read()
  rcutorture: Use per-CPU random state for rcu_torture_timer()
  rcutorture: Use atomic increment for n_rcu_torture_timers
  rcutorture: Extract common code from rcu_torture_reader()
  rcuperf: Remove unused torturing_tasks() function
  rcu: Remove rcutorture test version and sequence number
  rcutorture: Change units of onoff_interval to jiffies
  rcu: Assign higher prio to RCU threads if rcutorture is built-in
  rculist: Improve documentation for list_for_each_entry_from_rcu()
  srcu: Add grace-period number to rcutorture statistics printout
  rcu: Print stall-warning NMI dyntick state in hexadecimal
  MAINTAINERS: Update RCU, SRCU, and TORTURE-TEST entries
  rcu: Make rcu_seq_diff() more exact
  ...

1 files changed, 17 insertions, 0 deletions

diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index 91494d7e8e41..3e72a291c401 100644
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -195,6 +195,16 @@ static inline int srcu_read_lock(struct srcu_struct *sp) __acquires(sp)
 	return retval;
 }
 
+/* Used by tracing, cannot be traced and cannot invoke lockdep. */
+static inline notrace int
+srcu_read_lock_notrace(struct srcu_struct *sp) __acquires(sp)
+{
+	int retval;
+
+	retval = __srcu_read_lock(sp);
+	return retval;
+}
+
 /**
  * srcu_read_unlock - unregister a old reader from an SRCU-protected structure.
  * @sp: srcu_struct in which to unregister the old reader.
@@ -209,6 +219,13 @@ static inline void srcu_read_unlock(struct srcu_struct *sp, int idx)
 	__srcu_read_unlock(sp, idx);
 }
 
+/* Used by tracing, cannot be traced and cannot call lockdep. */
+static inline notrace void
+srcu_read_unlock_notrace(struct srcu_struct *sp, int idx) __releases(sp)
+{
+	__srcu_read_unlock(sp, idx);
+}
+
 /**
  * smp_mb__after_srcu_read_unlock - ensure full ordering after srcu_read_unlock
  *