rcu: Convert rcu_grace_period tracepoint to gp_seq

This commit makes the rcu_grace_period tracepoint use gp_seq instead
of ->gpnum or ->completed.  It also introduces a "cpuofl-bgp" string to
less obscurely indicate when a CPU has gone offline while a grace period
is waiting on it.

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

1 files changed, 21 insertions, 22 deletions

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 4826598867c3..7ce85ad39af6 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -234,7 +234,7 @@ void rcu_sched_qs(void)
         if (!__this_cpu_read(rcu_sched_data.cpu_no_qs.s))
                 return;
         trace_rcu_grace_period(TPS("rcu_sched"),
-                               __this_cpu_read(rcu_sched_data.gpnum),
+                               __this_cpu_read(rcu_sched_data.gp_seq),
                                TPS("cpuqs"));
         __this_cpu_write(rcu_sched_data.cpu_no_qs.b.norm, false);
         if (!__this_cpu_read(rcu_sched_data.cpu_no_qs.b.exp))
@@ -249,7 +249,7 @@ void rcu_bh_qs(void)
         RCU_LOCKDEP_WARN(preemptible(), "rcu_bh_qs() invoked with preemption enabled!!!");
         if (__this_cpu_read(rcu_bh_data.cpu_no_qs.s)) {
                 trace_rcu_grace_period(TPS("rcu_bh"),
-                                       __this_cpu_read(rcu_bh_data.gpnum),
+                                       __this_cpu_read(rcu_bh_data.gp_seq),
                                        TPS("cpuqs"));
                 __this_cpu_write(rcu_bh_data.cpu_no_qs.b.norm, false);
         }
@@ -1615,7 +1615,7 @@ static bool rcu_start_this_gp(struct rcu_node *rnp, struct rcu_data *rdp,
                 trace_rcu_this_gp(rnp_root, rdp, c, TPS("NoGPkthread"));
                 goto unlock_out;
         }
-        trace_rcu_grace_period(rsp->name, READ_ONCE(rsp->gpnum), TPS("newreq"));
+        trace_rcu_grace_period(rsp->name, READ_ONCE(rsp->gp_seq), TPS("newreq"));
         ret = true;  /* Caller must wake GP kthread. */
 unlock_out:
         /* Push furthest requested GP to leaf node and rcu_data structure. */
@@ -1702,9 +1702,9 @@ static bool rcu_accelerate_cbs(struct rcu_state *rsp, struct rcu_node *rnp,
 
         /* Trace depending on how much we were able to accelerate. */
         if (rcu_segcblist_restempty(&rdp->cblist, RCU_WAIT_TAIL))
-                trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("AccWaitCB"));
+                trace_rcu_grace_period(rsp->name, rdp->gp_seq, TPS("AccWaitCB"));
         else
-                trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("AccReadyCB"));
+                trace_rcu_grace_period(rsp->name, rdp->gp_seq, TPS("AccReadyCB"));
         return ret;
 }
 
@@ -1774,7 +1774,7 @@ static bool __note_gp_changes(struct rcu_state *rsp, struct rcu_node *rnp,
                  * go looking for one.
                  */
                 rdp->gpnum = rnp->gpnum;
-                trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("cpustart"));
+                trace_rcu_grace_period(rsp->name, rdp->gp_seq, TPS("cpustart"));
                 need_gp = !!(rnp->qsmask & rdp->grpmask);
                 rdp->cpu_no_qs.b.norm = need_gp;
                 rdp->rcu_qs_ctr_snap = __this_cpu_read(rcu_dynticks.rcu_qs_ctr);
@@ -1851,7 +1851,7 @@ static bool rcu_gp_init(struct rcu_state *rsp)
         rcu_seq_start(&rsp->gp_seq);
         if (WARN_ON_ONCE(((rnp->completed << RCU_SEQ_CTR_SHIFT) >> RCU_SEQ_CTR_SHIFT) != rcu_seq_ctr(rnp->gp_seq))) /* Catch any ->completed/->gp_seq mismatches. */
                 pr_info("%s ->completed: %#lx (%#lx) ->gp_seq %#lx (%#lx)\n", __func__, rnp->completed, (rnp->completed << RCU_SEQ_CTR_SHIFT) >> RCU_SEQ_CTR_SHIFT, rnp->gp_seq, rcu_seq_ctr(rnp->gp_seq));
-        trace_rcu_grace_period(rsp->name, rsp->gpnum, TPS("start"));
+        trace_rcu_grace_period(rsp->name, rsp->gp_seq, TPS("start"));
         raw_spin_unlock_irq_rcu_node(rnp);
 
         /*
@@ -1928,7 +1928,7 @@ static bool rcu_gp_init(struct rcu_state *rsp)
                 if (rnp == rdp->mynode)
                         (void)__note_gp_changes(rsp, rnp, rdp);
                 rcu_preempt_boost_start_gp(rnp);
-                trace_rcu_grace_period_init(rsp->name, rnp->gpnum,
+                trace_rcu_grace_period_init(rsp->name, rnp->gp_seq,
                                             rnp->level, rnp->grplo,
                                             rnp->grphi, rnp->qsmask);
                 raw_spin_unlock_irq_rcu_node(rnp);
@@ -2048,7 +2048,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
         /* Declare grace period done. */
         WRITE_ONCE(rsp->completed, rsp->gpnum);
         rcu_seq_end(&rsp->gp_seq);
-        trace_rcu_grace_period(rsp->name, rsp->completed, TPS("end"));
+        trace_rcu_grace_period(rsp->name, rsp->gp_seq, TPS("end"));
         rsp->gp_state = RCU_GP_IDLE;
         /* Check for GP requests since above loop. */
         rdp = this_cpu_ptr(rsp->rda);
@@ -2061,7 +2061,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
         if (!rcu_accelerate_cbs(rsp, rnp, rdp) && needgp) {
                 WRITE_ONCE(rsp->gp_flags, RCU_GP_FLAG_INIT);
                 rsp->gp_req_activity = jiffies;
-                trace_rcu_grace_period(rsp->name, READ_ONCE(rsp->gpnum),
+                trace_rcu_grace_period(rsp->name, READ_ONCE(rsp->gp_seq),
                                        TPS("newreq"));
         } else {
                 WRITE_ONCE(rsp->gp_flags, rsp->gp_flags & RCU_GP_FLAG_INIT);
@@ -2087,7 +2087,7 @@ static int __noreturn rcu_gp_kthread(void *arg)
                 /* Handle grace-period start. */
                 for (;;) {
                         trace_rcu_grace_period(rsp->name,
-                                               READ_ONCE(rsp->gpnum),
+                                               READ_ONCE(rsp->gp_seq),
                                                TPS("reqwait"));
                         rsp->gp_state = RCU_GP_WAIT_GPS;
                         swait_event_idle(rsp->gp_wq, READ_ONCE(rsp->gp_flags) &
@@ -2100,7 +2100,7 @@ static int __noreturn rcu_gp_kthread(void *arg)
                         WRITE_ONCE(rsp->gp_activity, jiffies);
                         WARN_ON(signal_pending(current));
                         trace_rcu_grace_period(rsp->name,
-                                               READ_ONCE(rsp->gpnum),
+                                               READ_ONCE(rsp->gp_seq),
                                                TPS("reqwaitsig"));
                 }
 
@@ -2119,7 +2119,7 @@ static int __noreturn rcu_gp_kthread(void *arg)
                                            jiffies + 3 * j);
                         }
                         trace_rcu_grace_period(rsp->name,
-                                               READ_ONCE(rsp->gpnum),
+                                               READ_ONCE(rsp->gp_seq),
                                                TPS("fqswait"));
                         rsp->gp_state = RCU_GP_WAIT_FQS;
                         ret = swait_event_idle_timeout(rsp->gp_wq,
@@ -2134,12 +2134,12 @@ static int __noreturn rcu_gp_kthread(void *arg)
                         if (ULONG_CMP_GE(jiffies, rsp->jiffies_force_qs) ||
                             (gf & RCU_GP_FLAG_FQS)) {
                                 trace_rcu_grace_period(rsp->name,
-                                                       READ_ONCE(rsp->gpnum),
+                                                       READ_ONCE(rsp->gp_seq),
                                                        TPS("fqsstart"));
                                 rcu_gp_fqs(rsp, first_gp_fqs);
                                 first_gp_fqs = false;
                                 trace_rcu_grace_period(rsp->name,
-                                                       READ_ONCE(rsp->gpnum),
+                                                       READ_ONCE(rsp->gp_seq),
                                                        TPS("fqsend"));
                                 cond_resched_tasks_rcu_qs();
                                 WRITE_ONCE(rsp->gp_activity, jiffies);
@@ -2158,7 +2158,7 @@ static int __noreturn rcu_gp_kthread(void *arg)
                                 WRITE_ONCE(rsp->gp_activity, jiffies);
                                 WARN_ON(signal_pending(current));
                                 trace_rcu_grace_period(rsp->name,
-                                                       READ_ONCE(rsp->gpnum),
+                                                       READ_ONCE(rsp->gp_seq),
                                                        TPS("fqswaitsig"));
                                 ret = 1; /* Keep old FQS timing. */
                                 j = jiffies;
@@ -2388,17 +2388,16 @@ rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp)
  */
 static void rcu_cleanup_dying_cpu(struct rcu_state *rsp)
 {
-        RCU_TRACE(unsigned long mask;)
+        RCU_TRACE(bool blkd;)
         RCU_TRACE(struct rcu_data *rdp = this_cpu_ptr(rsp->rda);)
         RCU_TRACE(struct rcu_node *rnp = rdp->mynode;)
 
         if (!IS_ENABLED(CONFIG_HOTPLUG_CPU))
                 return;
 
-        RCU_TRACE(mask = rdp->grpmask;)
-        trace_rcu_grace_period(rsp->name,
-                               rnp->gpnum + 1 - !!(rnp->qsmask & mask),
-                               TPS("cpuofl"));
+        RCU_TRACE(blkd = !!(rnp->qsmask & rdp->grpmask);)
+        trace_rcu_grace_period(rsp->name, rnp->gp_seq,
+                               blkd ? TPS("cpuofl") : TPS("cpuofl-bgp"));
 }
 
 /*
@@ -3538,7 +3537,7 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
         rdp->core_needs_qs = false;
         rdp->rcu_iw_pending = false;
         rdp->rcu_iw_gp_seq = rnp->gp_seq - 1;
-        trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("cpuonl"));
+        trace_rcu_grace_period(rsp->name, rdp->gp_seq, TPS("cpuonl"));
         raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
 }