rcu: Repurpose no-CBs event tracing to future-GP events

Dyntick-idle CPUs need to be able to pre-announce their need for grace
periods.  This can be done using something similar to the mechanism used
by no-CB CPUs to announce their need for grace periods.  This commit
moves in this direction by renaming the no-CBs grace-period event tracing
to suit the new future-grace-period needs.

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

2 files changed, 40 insertions, 38 deletions

diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h
index cdfed6d386eb..59ebcc89f148 100644
--- a/include/trace/events/rcu.h
+++ b/include/trace/events/rcu.h
@@ -72,10 +72,10 @@ TRACE_EVENT(rcu_grace_period,
 );
 
 /*
- * Tracepoint for no-callbacks grace-period events.  The caller should
- * pull the data from the rcu_node structure, other than rcuname, which
- * comes from the rcu_state structure, and event, which is one of the
- * following:
+ * Tracepoint for future grace-period events, including those for no-callbacks
+ * CPUs.  The caller should pull the data from the rcu_node structure,
+ * other than rcuname, which comes from the rcu_state structure, and event,
+ * which is one of the following:
  *
  * "Startleaf": Request a nocb grace period based on leaf-node data.
  * "Startedleaf": Leaf-node start proved sufficient.
@@ -87,7 +87,7 @@ TRACE_EVENT(rcu_grace_period,
  * "Cleanup": Clean up rcu_node structure after previous GP.
  * "CleanupMore": Clean up, and another no-CB GP is needed.
  */
-TRACE_EVENT(rcu_nocb_grace_period,
+TRACE_EVENT(rcu_future_grace_period,
 
         TP_PROTO(char *rcuname, unsigned long gpnum, unsigned long completed,
                  unsigned long c, u8 level, int grplo, int grphi,
@@ -653,9 +653,9 @@ TRACE_EVENT(rcu_barrier,
 #define trace_rcu_grace_period(rcuname, gpnum, gpevent) do { } while (0)
 #define trace_rcu_grace_period_init(rcuname, gpnum, level, grplo, grphi, \
                                     qsmask) do { } while (0)
-#define trace_rcu_nocb_grace_period(rcuname, gpnum, completed, c, \
-                                    level, grplo, grphi, event) \
-                                    do { } while (0)
+#define trace_rcu_future_grace_period(rcuname, gpnum, completed, c, \
+                                      level, grplo, grphi, event) \
+                                      do { } while (0)
 #define trace_rcu_preempt_task(rcuname, pid, gpnum) do { } while (0)
 #define trace_rcu_unlock_preempted_task(rcuname, gpnum, pid) do { } while (0)
 #define trace_rcu_quiescent_state_report(rcuname, gpnum, mask, qsmask, level, \
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index d318f9f18be5..df50502eca2c 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -2034,9 +2034,9 @@ static int rcu_nocb_gp_cleanup(struct rcu_state *rsp, struct rcu_node *rnp)
         wake_up_all(&rnp->nocb_gp_wq[c & 0x1]);
         rnp->n_nocb_gp_requests[c & 0x1] = 0;
         needmore = rnp->n_nocb_gp_requests[(c + 1) & 0x1];
-        trace_rcu_nocb_grace_period(rsp->name, rnp->gpnum, rnp->completed,
-                                    c, rnp->level, rnp->grplo, rnp->grphi,
-                                    needmore ? "CleanupMore" : "Cleanup");
+        trace_rcu_future_grace_period(rsp->name, rnp->gpnum, rnp->completed,
+                                      c, rnp->level, rnp->grplo, rnp->grphi,
+                                      needmore ? "CleanupMore" : "Cleanup");
         return needmore;
 }
 
@@ -2183,9 +2183,9 @@ static void rcu_nocb_wait_gp(struct rcu_data *rdp)
 
         /* Count our request for a grace period. */
         rnp->n_nocb_gp_requests[c & 0x1]++;
-        trace_rcu_nocb_grace_period(rdp->rsp->name, rnp->gpnum, rnp->completed,
-                                    c, rnp->level, rnp->grplo, rnp->grphi,
-                                    "Startleaf");
+        trace_rcu_future_grace_period(rdp->rsp->name, rnp->gpnum,
+                                      rnp->completed, c, rnp->level,
+                                      rnp->grplo, rnp->grphi, "Startleaf");
 
         if (rnp->gpnum != rnp->completed) {
 
@@ -2194,10 +2194,10 @@ static void rcu_nocb_wait_gp(struct rcu_data *rdp)
                  * is in progress, so we are done.  When this grace
                  * period ends, our request will be acted upon.
                  */
-                trace_rcu_nocb_grace_period(rdp->rsp->name,
-                                            rnp->gpnum, rnp->completed, c,
-                                            rnp->level, rnp->grplo, rnp->grphi,
-                                            "Startedleaf");
+                trace_rcu_future_grace_period(rdp->rsp->name, rnp->gpnum,
+                                              rnp->completed, c, rnp->level,
+                                              rnp->grplo, rnp->grphi,
+                                              "Startedleaf");
                 raw_spin_unlock_irqrestore(&rnp->lock, flags);
 
         } else {
@@ -2209,11 +2209,12 @@ static void rcu_nocb_wait_gp(struct rcu_data *rdp)
                 if (rnp != rnp_root)
                         raw_spin_lock(&rnp_root->lock); /* irqs disabled. */
                 if (rnp_root->gpnum != rnp_root->completed) {
-                        trace_rcu_nocb_grace_period(rdp->rsp->name,
-                                                    rnp->gpnum, rnp->completed,
-                                                    c, rnp->level,
-                                                    rnp->grplo, rnp->grphi,
-                                                    "Startedleafroot");
+                        trace_rcu_future_grace_period(rdp->rsp->name,
+                                                      rnp->gpnum,
+                                                      rnp->completed,
+                                                      c, rnp->level,
+                                                      rnp->grplo, rnp->grphi,
+                                                      "Startedleafroot");
                         raw_spin_unlock(&rnp_root->lock); /* irqs disabled. */
                 } else {
 
@@ -2229,11 +2230,12 @@ static void rcu_nocb_wait_gp(struct rcu_data *rdp)
                         c = rnp_root->completed + 1;
                         rnp->n_nocb_gp_requests[c & 0x1]++;
                         rnp_root->n_nocb_gp_requests[c & 0x1]++;
-                        trace_rcu_nocb_grace_period(rdp->rsp->name,
-                                                    rnp->gpnum, rnp->completed,
-                                                    c, rnp->level,
-                                                    rnp->grplo, rnp->grphi,
-                                                    "Startedroot");
+                        trace_rcu_future_grace_period(rdp->rsp->name,
+                                                      rnp->gpnum,
+                                                      rnp->completed,
+                                                      c, rnp->level,
+                                                      rnp->grplo, rnp->grphi,
+                                                      "Startedroot");
                         local_save_flags(flags1);
                         rcu_start_gp(rdp->rsp, flags1); /* Rlses ->lock. */
                 }
@@ -2249,9 +2251,9 @@ static void rcu_nocb_wait_gp(struct rcu_data *rdp)
          * Wait for the grace period.  Do so interruptibly to avoid messing
          * up the load average.
          */
-        trace_rcu_nocb_grace_period(rdp->rsp->name, rnp->gpnum, rnp->completed,
-                                    c, rnp->level, rnp->grplo, rnp->grphi,
-                                    "StartWait");
+        trace_rcu_future_grace_period(rdp->rsp->name, rnp->gpnum,
+                                      rnp->completed, c, rnp->level,
+                                      rnp->grplo, rnp->grphi, "StartWait");
         for (;;) {
                 wait_event_interruptible(
                         rnp->nocb_gp_wq[c & 0x1],
@@ -2259,14 +2261,14 @@ static void rcu_nocb_wait_gp(struct rcu_data *rdp)
                 if (likely(d))
                         break;
                 flush_signals(current);
-                trace_rcu_nocb_grace_period(rdp->rsp->name,
-                                            rnp->gpnum, rnp->completed, c,
-                                            rnp->level, rnp->grplo, rnp->grphi,
-                                            "ResumeWait");
+                trace_rcu_future_grace_period(rdp->rsp->name,
+                                              rnp->gpnum, rnp->completed, c,
+                                              rnp->level, rnp->grplo,
+                                              rnp->grphi, "ResumeWait");
         }
-        trace_rcu_nocb_grace_period(rdp->rsp->name, rnp->gpnum, rnp->completed,
-                                    c, rnp->level, rnp->grplo, rnp->grphi,
-                                    "EndWait");
+        trace_rcu_future_grace_period(rdp->rsp->name, rnp->gpnum,
+                                      rnp->completed, c, rnp->level,
+                                      rnp->grplo, rnp->grphi, "EndWait");
         smp_mb(); /* Ensure that CB invocation happens after GP end. */
 }