5 files changed, 49 insertions, 49 deletions

diff --git a/Documentation/RCU/trace.txt b/Documentation/RCU/trace.txt
index a67af0a39ded..aaf65f6c6cd7 100644
--- a/Documentation/RCU/trace.txt
+++ b/Documentation/RCU/trace.txt
@@ -33,23 +33,23 @@ rcu/rcuboost:
 The output of "cat rcu/rcudata" looks as follows:
 
 rcu_sched:
-  0 c=20972 g=20973 pq=1 pqc=20972 qp=0 dt=545/1/0 df=50 of=0 ri=0 ql=163 qs=NRW. kt=0/W/0 ktl=ebc3 b=10 ci=153737 co=0 ca=0
-  1 c=20972 g=20973 pq=1 pqc=20972 qp=0 dt=967/1/0 df=58 of=0 ri=0 ql=634 qs=NRW. kt=0/W/1 ktl=58c b=10 ci=191037 co=0 ca=0
-  2 c=20972 g=20973 pq=1 pqc=20972 qp=0 dt=1081/1/0 df=175 of=0 ri=0 ql=74 qs=N.W. kt=0/W/2 ktl=da94 b=10 ci=75991 co=0 ca=0
-  3 c=20942 g=20943 pq=1 pqc=20942 qp=1 dt=1846/0/0 df=404 of=0 ri=0 ql=0 qs=.... kt=0/W/3 ktl=d1cd b=10 ci=72261 co=0 ca=0
-  4 c=20972 g=20973 pq=1 pqc=20972 qp=0 dt=369/1/0 df=83 of=0 ri=0 ql=48 qs=N.W. kt=0/W/4 ktl=e0e7 b=10 ci=128365 co=0 ca=0
-  5 c=20972 g=20973 pq=1 pqc=20972 qp=0 dt=381/1/0 df=64 of=0 ri=0 ql=169 qs=NRW. kt=0/W/5 ktl=fb2f b=10 ci=164360 co=0 ca=0
-  6 c=20972 g=20973 pq=1 pqc=20972 qp=0 dt=1037/1/0 df=183 of=0 ri=0 ql=62 qs=N.W. kt=0/W/6 ktl=d2ad b=10 ci=65663 co=0 ca=0
-  7 c=20897 g=20897 pq=1 pqc=20896 qp=0 dt=1572/0/0 df=382 of=0 ri=0 ql=0 qs=.... kt=0/W/7 ktl=cf15 b=10 ci=75006 co=0 ca=0
+  0 c=20972 g=20973 pq=1 pgp=20973 qp=0 dt=545/1/0 df=50 of=0 ri=0 ql=163 qs=NRW. kt=0/W/0 ktl=ebc3 b=10 ci=153737 co=0 ca=0
+  1 c=20972 g=20973 pq=1 pgp=20973 qp=0 dt=967/1/0 df=58 of=0 ri=0 ql=634 qs=NRW. kt=0/W/1 ktl=58c b=10 ci=191037 co=0 ca=0
+  2 c=20972 g=20973 pq=1 pgp=20973 qp=0 dt=1081/1/0 df=175 of=0 ri=0 ql=74 qs=N.W. kt=0/W/2 ktl=da94 b=10 ci=75991 co=0 ca=0
+  3 c=20942 g=20943 pq=1 pgp=20942 qp=1 dt=1846/0/0 df=404 of=0 ri=0 ql=0 qs=.... kt=0/W/3 ktl=d1cd b=10 ci=72261 co=0 ca=0
+  4 c=20972 g=20973 pq=1 pgp=20973 qp=0 dt=369/1/0 df=83 of=0 ri=0 ql=48 qs=N.W. kt=0/W/4 ktl=e0e7 b=10 ci=128365 co=0 ca=0
+  5 c=20972 g=20973 pq=1 pgp=20973 qp=0 dt=381/1/0 df=64 of=0 ri=0 ql=169 qs=NRW. kt=0/W/5 ktl=fb2f b=10 ci=164360 co=0 ca=0
+  6 c=20972 g=20973 pq=1 pgp=20973 qp=0 dt=1037/1/0 df=183 of=0 ri=0 ql=62 qs=N.W. kt=0/W/6 ktl=d2ad b=10 ci=65663 co=0 ca=0
+  7 c=20897 g=20897 pq=1 pgp=20896 qp=0 dt=1572/0/0 df=382 of=0 ri=0 ql=0 qs=.... kt=0/W/7 ktl=cf15 b=10 ci=75006 co=0 ca=0
 rcu_bh:
-  0 c=1480 g=1480 pq=1 pqc=1479 qp=0 dt=545/1/0 df=6 of=0 ri=1 ql=0 qs=.... kt=0/W/0 ktl=ebc3 b=10 ci=0 co=0 ca=0
-  1 c=1480 g=1480 pq=1 pqc=1479 qp=0 dt=967/1/0 df=3 of=0 ri=1 ql=0 qs=.... kt=0/W/1 ktl=58c b=10 ci=151 co=0 ca=0
-  2 c=1480 g=1480 pq=1 pqc=1479 qp=0 dt=1081/1/0 df=6 of=0 ri=1 ql=0 qs=.... kt=0/W/2 ktl=da94 b=10 ci=0 co=0 ca=0
-  3 c=1480 g=1480 pq=1 pqc=1479 qp=0 dt=1846/0/0 df=8 of=0 ri=1 ql=0 qs=.... kt=0/W/3 ktl=d1cd b=10 ci=0 co=0 ca=0
-  4 c=1480 g=1480 pq=1 pqc=1479 qp=0 dt=369/1/0 df=6 of=0 ri=1 ql=0 qs=.... kt=0/W/4 ktl=e0e7 b=10 ci=0 co=0 ca=0
-  5 c=1480 g=1480 pq=1 pqc=1479 qp=0 dt=381/1/0 df=4 of=0 ri=1 ql=0 qs=.... kt=0/W/5 ktl=fb2f b=10 ci=0 co=0 ca=0
-  6 c=1480 g=1480 pq=1 pqc=1479 qp=0 dt=1037/1/0 df=6 of=0 ri=1 ql=0 qs=.... kt=0/W/6 ktl=d2ad b=10 ci=0 co=0 ca=0
-  7 c=1474 g=1474 pq=1 pqc=1473 qp=0 dt=1572/0/0 df=8 of=0 ri=1 ql=0 qs=.... kt=0/W/7 ktl=cf15 b=10 ci=0 co=0 ca=0
+  0 c=1480 g=1480 pq=1 pgp=1480 qp=0 dt=545/1/0 df=6 of=0 ri=1 ql=0 qs=.... kt=0/W/0 ktl=ebc3 b=10 ci=0 co=0 ca=0
+  1 c=1480 g=1480 pq=1 pgp=1480 qp=0 dt=967/1/0 df=3 of=0 ri=1 ql=0 qs=.... kt=0/W/1 ktl=58c b=10 ci=151 co=0 ca=0
+  2 c=1480 g=1480 pq=1 pgp=1480 qp=0 dt=1081/1/0 df=6 of=0 ri=1 ql=0 qs=.... kt=0/W/2 ktl=da94 b=10 ci=0 co=0 ca=0
+  3 c=1480 g=1480 pq=1 pgp=1480 qp=0 dt=1846/0/0 df=8 of=0 ri=1 ql=0 qs=.... kt=0/W/3 ktl=d1cd b=10 ci=0 co=0 ca=0
+  4 c=1480 g=1480 pq=1 pgp=1480 qp=0 dt=369/1/0 df=6 of=0 ri=1 ql=0 qs=.... kt=0/W/4 ktl=e0e7 b=10 ci=0 co=0 ca=0
+  5 c=1480 g=1480 pq=1 pgp=1480 qp=0 dt=381/1/0 df=4 of=0 ri=1 ql=0 qs=.... kt=0/W/5 ktl=fb2f b=10 ci=0 co=0 ca=0
+  6 c=1480 g=1480 pq=1 pgp=1480 qp=0 dt=1037/1/0 df=6 of=0 ri=1 ql=0 qs=.... kt=0/W/6 ktl=d2ad b=10 ci=0 co=0 ca=0
+  7 c=1474 g=1474 pq=1 pgp=1473 qp=0 dt=1572/0/0 df=8 of=0 ri=1 ql=0 qs=.... kt=0/W/7 ktl=cf15 b=10 ci=0 co=0 ca=0
 
 The first section lists the rcu_data structures for rcu_sched, the second
 for rcu_bh.  Note that CONFIG_TREE_PREEMPT_RCU kernels will have an
@@ -84,7 +84,7 @@ o	"pq" indicates that this CPU has passed through a quiescent state
         CPU has not yet reported that fact, (2) some other CPU has not
         yet reported for this grace period, or (3) both.
 
-o       "pqc" indicates which grace period the last-observed quiescent
+o       "pgp" indicates which grace period the last-observed quiescent
         state for this CPU corresponds to.  This is important for handling
         the race between CPU 0 reporting an extended dynticks-idle
         quiescent state for CPU 1 and CPU 1 suddenly waking up and
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 7e0282949f8a..7e2f297aeec8 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -159,32 +159,34 @@ static int rcu_gp_in_progress(struct rcu_state *rsp)
  * Note a quiescent state.  Because we do not need to know
  * how many quiescent states passed, just if there was at least
  * one since the start of the grace period, this just sets a flag.
+ * The caller must have disabled preemption.
  */
 void rcu_sched_qs(int cpu)
 {
         struct rcu_data *rdp = &per_cpu(rcu_sched_data, cpu);
 
-        rdp->passed_quiesc_completed = rdp->gpnum - 1;
+        rdp->passed_quiesce_gpnum = rdp->gpnum;
         barrier();
-        if (rdp->passed_quiesc == 0)
+        if (rdp->passed_quiesce == 0)
                 trace_rcu_grace_period("rcu_sched", rdp->gpnum, "cpuqs");
-        rdp->passed_quiesc = 1;
+        rdp->passed_quiesce = 1;
 }
 
 void rcu_bh_qs(int cpu)
 {
         struct rcu_data *rdp = &per_cpu(rcu_bh_data, cpu);
 
-        rdp->passed_quiesc_completed = rdp->gpnum - 1;
+        rdp->passed_quiesce_gpnum = rdp->gpnum;
         barrier();
-        if (rdp->passed_quiesc == 0)
+        if (rdp->passed_quiesce == 0)
                 trace_rcu_grace_period("rcu_bh", rdp->gpnum, "cpuqs");
-        rdp->passed_quiesc = 1;
+        rdp->passed_quiesce = 1;
 }
 
 /*
  * Note a context switch.  This is a quiescent state for RCU-sched,
  * and requires special handling for preemptible RCU.
+ * The caller must have disabled preemption.
  */
 void rcu_note_context_switch(int cpu)
 {
@@ -694,7 +696,7 @@ static void __note_new_gpnum(struct rcu_state *rsp, struct rcu_node *rnp, struct
                 trace_rcu_grace_period(rsp->name, rdp->gpnum, "cpustart");
                 if (rnp->qsmask & rdp->grpmask) {
                         rdp->qs_pending = 1;
-                        rdp->passed_quiesc = 0;
+                        rdp->passed_quiesce = 0;
                 } else
                         rdp->qs_pending = 0;
         }
@@ -1027,7 +1029,7 @@ rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp,
  * based on quiescent states detected in an earlier grace period!
  */
 static void
-rcu_report_qs_rdp(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long lastcomp)
+rcu_report_qs_rdp(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long lastgp)
 {
         unsigned long flags;
         unsigned long mask;
@@ -1035,17 +1037,15 @@ rcu_report_qs_rdp(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long las
 
         rnp = rdp->mynode;
         raw_spin_lock_irqsave(&rnp->lock, flags);
-        if (lastcomp != rnp->completed) {
+        if (lastgp != rnp->gpnum || rnp->completed == rnp->gpnum) {
 
                 /*
-                 * Someone beat us to it for this grace period, so leave.
-                 * The race with GP start is resolved by the fact that we
-                 * hold the leaf rcu_node lock, so that the per-CPU bits
-                 * cannot yet be initialized -- so we would simply find our
-                 * CPU's bit already cleared in rcu_report_qs_rnp() if this
-                 * race occurred.
+                 * The grace period in which this quiescent state was
+                 * recorded has ended, so don't report it upwards.
+                 * We will instead need a new quiescent state that lies
+                 * within the current grace period.
                  */
-                rdp->passed_quiesc = 0; /* try again later! */
+                rdp->passed_quiesce = 0;        /* need qs for new gp. */
                 raw_spin_unlock_irqrestore(&rnp->lock, flags);
                 return;
         }
@@ -1089,14 +1089,14 @@ rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp)
          * Was there a quiescent state since the beginning of the grace
          * period? If no, then exit and wait for the next call.
          */
-        if (!rdp->passed_quiesc)
+        if (!rdp->passed_quiesce)
                 return;
 
         /*
          * Tell RCU we are done (but rcu_report_qs_rdp() will be the
          * judge of that).
          */
-        rcu_report_qs_rdp(rdp->cpu, rsp, rdp, rdp->passed_quiesc_completed);
+        rcu_report_qs_rdp(rdp->cpu, rsp, rdp, rdp->passed_quiesce_gpnum);
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
@@ -1712,7 +1712,7 @@ static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp)
         check_cpu_stall(rsp, rdp);
 
         /* Is the RCU core waiting for a quiescent state from this CPU? */
-        if (rdp->qs_pending && !rdp->passed_quiesc) {
+        if (rdp->qs_pending && !rdp->passed_quiesce) {
 
                 /*
                  * If force_quiescent_state() coming soon and this CPU
@@ -1724,7 +1724,7 @@ static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp)
                     ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs) - 1,
                                  jiffies))
                         set_need_resched();
-        } else if (rdp->qs_pending && rdp->passed_quiesc) {
+        } else if (rdp->qs_pending && rdp->passed_quiesce) {
                 rdp->n_rp_report_qs++;
                 return 1;
         }
@@ -1907,7 +1907,7 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptible)
 
         /* Set up local state, ensuring consistent view of global state. */
         raw_spin_lock_irqsave(&rnp->lock, flags);
-        rdp->passed_quiesc = 0;  /* We could be racing with new GP, */
+        rdp->passed_quiesce = 0;  /* We could be racing with new GP, */
         rdp->qs_pending = 1;     /*  so set up to respond to current GP. */
         rdp->beenonline = 1;     /* We have now been online. */
         rdp->preemptible = preemptible;
@@ -1935,7 +1935,7 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptible)
                 if (rnp == rdp->mynode) {
                         rdp->gpnum = rnp->completed; /* if GP in progress... */
                         rdp->completed = rnp->completed;
-                        rdp->passed_quiesc_completed = rnp->completed - 1;
+                        rdp->passed_quiesce_gpnum = rnp->gpnum - 1;
                         trace_rcu_grace_period(rsp->name, rdp->gpnum, "cpuonl");
                 }
                 raw_spin_unlock(&rnp->lock); /* irqs already disabled. */
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index d11a0065321c..51638b68b2dc 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -230,9 +230,9 @@ struct rcu_data {
                                         /*  in order to detect GP end. */
         unsigned long   gpnum;          /* Highest gp number that this CPU */
                                         /*  is aware of having started. */
-        unsigned long   passed_quiesc_completed;
-                                        /* Value of completed at time of qs. */
-        bool            passed_quiesc;  /* User-mode/idle loop etc. */
+        unsigned long   passed_quiesce_gpnum;
+                                        /* gpnum at time of quiescent state. */
+        bool            passed_quiesce; /* User-mode/idle loop etc. */
         bool            qs_pending;     /* Core waits for quiesc state. */
         bool            beenonline;     /* CPU online at least once. */
         bool            preemptible;    /* Preemptible RCU? */
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index bdb2e82f78d3..4bac5a29fb69 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -122,11 +122,11 @@ static void rcu_preempt_qs(int cpu)
 {
         struct rcu_data *rdp = &per_cpu(rcu_preempt_data, cpu);
 
-        rdp->passed_quiesc_completed = rdp->gpnum - 1;
+        rdp->passed_quiesce_gpnum = rdp->gpnum;
         barrier();
-        if (rdp->passed_quiesc == 0)
+        if (rdp->passed_quiesce == 0)
                 trace_rcu_grace_period("rcu_preempt", rdp->gpnum, "cpuqs");
-        rdp->passed_quiesc = 1;
+        rdp->passed_quiesce = 1;
         current->rcu_read_unlock_special &= ~RCU_READ_UNLOCK_NEED_QS;
 }
 
diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c
index f328ed1c6e46..9feffa4c0695 100644
--- a/kernel/rcutree_trace.c
+++ b/kernel/rcutree_trace.c
@@ -61,11 +61,11 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
 {
         if (!rdp->beenonline)
                 return;
-        seq_printf(m, "%3d%cc=%lu g=%lu pq=%d pqc=%lu qp=%d",
+        seq_printf(m, "%3d%cc=%lu g=%lu pq=%d pgp=%lu qp=%d",
                    rdp->cpu,
                    cpu_is_offline(rdp->cpu) ? '!' : ' ',
                    rdp->completed, rdp->gpnum,
-                   rdp->passed_quiesc, rdp->passed_quiesc_completed,
+                   rdp->passed_quiesce, rdp->passed_quiesce_gpnum,
                    rdp->qs_pending);
 #ifdef CONFIG_NO_HZ
         seq_printf(m, " dt=%d/%d/%d df=%lu",
@@ -139,7 +139,7 @@ static void print_one_rcu_data_csv(struct seq_file *m, struct rcu_data *rdp)
                    rdp->cpu,
                    cpu_is_offline(rdp->cpu) ? "\"N\"" : "\"Y\"",
                    rdp->completed, rdp->gpnum,
-                   rdp->passed_quiesc, rdp->passed_quiesc_completed,
+                   rdp->passed_quiesce, rdp->passed_quiesce_gpnum,
                    rdp->qs_pending);
 #ifdef CONFIG_NO_HZ
         seq_printf(m, ",%d,%d,%d,%lu",
@@ -170,7 +170,7 @@ static void print_one_rcu_data_csv(struct seq_file *m, struct rcu_data *rdp)
 
 static int show_rcudata_csv(struct seq_file *m, void *unused)
 {
-        seq_puts(m, "\"CPU\",\"Online?\",\"c\",\"g\",\"pq\",\"pqc\",\"pq\",");
+        seq_puts(m, "\"CPU\",\"Online?\",\"c\",\"g\",\"pq\",\"pgp\",\"pq\",");
 #ifdef CONFIG_NO_HZ
         seq_puts(m, "\"dt\",\"dt nesting\",\"dt NMI nesting\",\"df\",");
 #endif /* #ifdef CONFIG_NO_HZ */