rcu: Add tracing for _rcu_barrier()

This commit adds event tracing for _rcu_barrier() execution.  This
is defined only if RCU_TRACE=y.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>

1 files changed, 45 insertions, 0 deletions

diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h
index d274734b2aa..5bde94d8585 100644
--- a/include/trace/events/rcu.h
+++ b/include/trace/events/rcu.h
@@ -541,6 +541,50 @@ TRACE_EVENT(rcu_torture_read,
                   __entry->rcutorturename, __entry->rhp)
 );
 
+/*
+ * Tracepoint for _rcu_barrier() execution.  The string "s" describes
+ * the _rcu_barrier phase:
+ *      "Begin": rcu_barrier_callback() started.
+ *      "Check": rcu_barrier_callback() checking for piggybacking.
+ *      "EarlyExit": rcu_barrier_callback() piggybacked, thus early exit.
+ *      "Inc1": rcu_barrier_callback() piggyback check counter incremented.
+ *      "Offline": rcu_barrier_callback() found offline CPU
+ *      "OnlineQ": rcu_barrier_callback() found online CPU with callbacks.
+ *      "OnlineNQ": rcu_barrier_callback() found online CPU, no callbacks.
+ *      "IRQ": An rcu_barrier_callback() callback posted on remote CPU.
+ *      "CB": An rcu_barrier_callback() invoked a callback, not the last.
+ *      "LastCB": An rcu_barrier_callback() invoked the last callback.
+ *      "Inc2": rcu_barrier_callback() piggyback check counter incremented.
+ * The "cpu" argument is the CPU or -1 if meaningless, the "cnt" argument
+ * is the count of remaining callbacks, and "done" is the piggybacking count.
+ */
+TRACE_EVENT(rcu_barrier,
+
+        TP_PROTO(char *rcuname, char *s, int cpu, int cnt, unsigned long done),
+
+        TP_ARGS(rcuname, s, cpu, cnt, done),
+
+        TP_STRUCT__entry(
+                __field(char *, rcuname)
+                __field(char *, s)
+                __field(int, cpu)
+                __field(int, cnt)
+                __field(unsigned long, done)
+        ),
+
+        TP_fast_assign(
+                __entry->rcuname = rcuname;
+                __entry->s = s;
+                __entry->cpu = cpu;
+                __entry->cnt = cnt;
+                __entry->done = done;
+        ),
+
+        TP_printk("%s %s cpu %d remaining %d # %lu",
+                  __entry->rcuname, __entry->s, __entry->cpu, __entry->cnt,
+                  __entry->done)
+);
+
 #else /* #ifdef CONFIG_RCU_TRACE */
 
 #define trace_rcu_grace_period(rcuname, gpnum, gpevent) do { } while (0)
@@ -564,6 +608,7 @@ TRACE_EVENT(rcu_torture_read,
 #define trace_rcu_batch_end(rcuname, callbacks_invoked, cb, nr, iit, risk) \
         do { } while (0)
 #define trace_rcu_torture_read(rcutorturename, rhp) do { } while (0)
+#define trace_rcu_barrier(name, s, cpu, cnt, done) do { } while (0)
 
 #endif /* #else #ifdef CONFIG_RCU_TRACE */