Merge branch 'rcu/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/urgent

Merge RCU fixes from Paul E. McKenney:

 " This series has four patches, the major point of which is to eliminate
   some slowdowns (including boot-time slowdowns) resulting from some
   RCU_FAST_NO_HZ changes.  The issue with the changes is that posting timers
   from the idle loop has no effect if the CPU has entered dyntick-idle
   mode because the CPU has already computed its wakeup time, and posting
   a timer does not cause it to be recomputed.  The short-term fix is for
   RCU to precompute the timeout value so that the CPU's calculation is
   correct. "

Signed-off-by: Ingo Molnar <mingo@kernel.org>

3 files changed, 6 insertions, 3 deletions

diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index adb5e5a38ca..854dc4c5c27 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -87,8 +87,9 @@ static inline void kfree_call_rcu(struct rcu_head *head,
 
 #ifdef CONFIG_TINY_RCU
 
-static inline int rcu_needs_cpu(int cpu)
+static inline int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies)
 {
+	*delta_jiffies = ULONG_MAX;
 	return 0;
 }
 
@@ -96,8 +97,9 @@ static inline int rcu_needs_cpu(int cpu)
 
 int rcu_preempt_needs_cpu(void);
 
-static inline int rcu_needs_cpu(int cpu)
+static inline int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies)
 {
+	*delta_jiffies = ULONG_MAX;
 	return rcu_preempt_needs_cpu();
 }
 
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index 3c6083cde4f..952b7933930 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -32,7 +32,7 @@
 
 extern void rcu_init(void);
 extern void rcu_note_context_switch(int cpu);
-extern int rcu_needs_cpu(int cpu);
+extern int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies);
 extern void rcu_cpu_stall_reset(void);
 
 /*
diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h
index 1480900c511..d274734b2aa 100644
--- a/include/trace/events/rcu.h
+++ b/include/trace/events/rcu.h
@@ -289,6 +289,7 @@ TRACE_EVENT(rcu_dyntick,
  *	"In holdoff": Nothing to do, holding off after unsuccessful attempt.
  *	"Begin holdoff": Attempt failed, don't retry until next jiffy.
  *	"Dyntick with callbacks": Entering dyntick-idle despite callbacks.
+ *	"Dyntick with lazy callbacks": Entering dyntick-idle w/lazy callbacks.
  *	"More callbacks": Still more callbacks, try again to clear them out.
  *	"Callbacks drained": All callbacks processed, off to dyntick idle!
  *	"Timer": Timer fired to cause CPU to continue processing callbacks.