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

Pull RCU updates from Paul E. McKenney:

- Updates to use cond_resched() instead of cond_resched_rcu_qs()
  where feasible (currently everywhere except in kernel/rcu and
  in kernel/torture.c).  Also a couple of fixes to avoid sending
  IPIs to offline CPUs.

- Updates to simplify RCU's dyntick-idle handling.

- Updates to remove almost all uses of smp_read_barrier_depends()
  and read_barrier_depends().

- Miscellaneous fixes.

- Torture-test updates.

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

1 files changed, 20 insertions, 55 deletions

diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h
index 59d40c454aa0..0b50fda80db0 100644
--- a/include/trace/events/rcu.h
+++ b/include/trace/events/rcu.h
@@ -243,6 +243,7 @@ TRACE_EVENT(rcu_exp_funnel_lock,
 		  __entry->grphi, __entry->gpevent)
 );
 
+#ifdef CONFIG_RCU_NOCB_CPU
 /*
  * Tracepoint for RCU no-CBs CPU callback handoffs.  This event is intended
  * to assist debugging of these handoffs.
@@ -285,6 +286,7 @@ TRACE_EVENT(rcu_nocb_wake,
 
 	TP_printk("%s %d %s", __entry->rcuname, __entry->cpu, __entry->reason)
 );
+#endif
 
 /*
  * Tracepoint for tasks blocking within preemptible-RCU read-side
@@ -421,76 +423,40 @@ TRACE_EVENT(rcu_fqs,
 
 /*
  * Tracepoint for dyntick-idle entry/exit events.  These take a string
- * as argument: "Start" for entering dyntick-idle mode, "End" for
- * leaving it, "--=" for events moving towards idle, and "++=" for events
- * moving away from idle.  "Error on entry: not idle task" and "Error on
- * exit: not idle task" indicate that a non-idle task is erroneously
- * toying with the idle loop.
+ * as argument: "Start" for entering dyntick-idle mode, "Startirq" for
+ * entering it from irq/NMI, "End" for leaving it, "Endirq" for leaving it
+ * to irq/NMI, "--=" for events moving towards idle, and "++=" for events
+ * moving away from idle.
  *
  * These events also take a pair of numbers, which indicate the nesting
- * depth before and after the event of interest.  Note that task-related
- * events use the upper bits of each number, while interrupt-related
- * events use the lower bits.
+ * depth before and after the event of interest, and a third number that is
+ * the ->dynticks counter.  Note that task-related and interrupt-related
+ * events use two separate counters, and that the "++=" and "--=" events
+ * for irq/NMI will change the counter by two, otherwise by one.
  */
 TRACE_EVENT(rcu_dyntick,
 
-	TP_PROTO(const char *polarity, long long oldnesting, long long newnesting),
+	TP_PROTO(const char *polarity, long oldnesting, long newnesting, atomic_t dynticks),
 
-	TP_ARGS(polarity, oldnesting, newnesting),
+	TP_ARGS(polarity, oldnesting, newnesting, dynticks),
 
 	TP_STRUCT__entry(
 		__field(const char *, polarity)
-		__field(long long, oldnesting)
-		__field(long long, newnesting)
+		__field(long, oldnesting)
+		__field(long, newnesting)
+		__field(int, dynticks)
 	),
 
 	TP_fast_assign(
 		__entry->polarity = polarity;
 		__entry->oldnesting = oldnesting;
 		__entry->newnesting = newnesting;
+		__entry->dynticks = atomic_read(&dynticks);
 	),
 
-	TP_printk("%s %llx %llx", __entry->polarity,
-		  __entry->oldnesting, __entry->newnesting)
-);
-
-/*
- * Tracepoint for RCU preparation for idle, the goal being to get RCU
- * processing done so that the current CPU can shut off its scheduling
- * clock and enter dyntick-idle mode.  One way to accomplish this is
- * to drain all RCU callbacks from this CPU, and the other is to have
- * done everything RCU requires for the current grace period.  In this
- * latter case, the CPU will be awakened at the end of the current grace
- * period in order to process the remainder of its callbacks.
- *
- * These tracepoints take a string as argument:
- *
- *	"No callbacks": Nothing to do, no callbacks on this CPU.
- *	"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.
- *	"Demigrate": Timer fired on wrong CPU, woke up correct CPU.
- *	"Cleanup after idle": Idle exited, timer canceled.
- */
-TRACE_EVENT(rcu_prep_idle,
-
-	TP_PROTO(const char *reason),
-
-	TP_ARGS(reason),
-
-	TP_STRUCT__entry(
-		__field(const char *, reason)
-	),
-
-	TP_fast_assign(
-		__entry->reason = reason;
-	),
-
-	TP_printk("%s", __entry->reason)
+	TP_printk("%s %lx %lx %#3x", __entry->polarity,
+		  __entry->oldnesting, __entry->newnesting,
+		  __entry->dynticks & 0xfff)
 );
 
 /*
@@ -799,8 +765,7 @@ TRACE_EVENT(rcu_barrier,
 					 grplo, grphi, gp_tasks) do { } \
 	while (0)
 #define trace_rcu_fqs(rcuname, gpnum, cpu, qsevent) do { } while (0)
-#define trace_rcu_dyntick(polarity, oldnesting, newnesting) do { } while (0)
-#define trace_rcu_prep_idle(reason) do { } while (0)
+#define trace_rcu_dyntick(polarity, oldnesting, newnesting, dyntick) do { } while (0)
 #define trace_rcu_callback(rcuname, rhp, qlen_lazy, qlen) do { } while (0)
 #define trace_rcu_kfree_callback(rcuname, rhp, offset, qlen_lazy, qlen) \
 	do { } while (0)