rcu: Renamings to increase RCU clarity

Make RCU-sched, RCU-bh, and RCU-preempt be underlying
implementations, with "RCU" defined in terms of one of the
three.  Update the outdated rcu_qsctr_inc() names, as these
functions no longer increment anything.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: akpm@linux-foundation.org
Cc: mathieu.desnoyers@polymtl.ca
Cc: josht@linux.vnet.ibm.com
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
LKML-Reference: <12509746132696-git-send-email->
Signed-off-by: Ingo Molnar <mingo@elte.hu>

6 files changed, 69 insertions, 49 deletions

diff --git a/kernel/rcupreempt.c b/kernel/rcupreempt.c
index 510898a7bd69..7d777c9f394c 100644
--- a/kernel/rcupreempt.c
+++ b/kernel/rcupreempt.c
@@ -159,7 +159,7 @@ static DEFINE_PER_CPU_SHARED_ALIGNED(struct rcu_dyntick_sched, rcu_dyntick_sched
         .dynticks = 1,
 };
 
-void rcu_qsctr_inc(int cpu)
+void rcu_sched_qs(int cpu)
 {
         struct rcu_dyntick_sched *rdssp = &per_cpu(rcu_dyntick_sched, cpu);
 
@@ -967,12 +967,12 @@ void rcu_check_callbacks(int cpu, int user)
          * If this CPU took its interrupt from user mode or from the
          * idle loop, and this is not a nested interrupt, then
          * this CPU has to have exited all prior preept-disable
-         * sections of code.  So increment the counter to note this.
+         * sections of code.  So invoke rcu_sched_qs() to note this.
          *
          * The memory barrier is needed to handle the case where
          * writes from a preempt-disable section of code get reordered
          * into schedule() by this CPU's write buffer.  So the memory
-         * barrier makes sure that the rcu_qsctr_inc() is seen by other
+         * barrier makes sure that the rcu_sched_qs() is seen by other
          * CPUs to happen after any such write.
          */
 
@@ -980,7 +980,7 @@ void rcu_check_callbacks(int cpu, int user)
             (idle_cpu(cpu) && !in_softirq() &&
              hardirq_count() <= (1 << HARDIRQ_SHIFT))) {
                 smp_mb();       /* Guard against aggressive schedule(). */
-                rcu_qsctr_inc(cpu);
+                rcu_sched_qs(cpu);
         }
 
         rcu_check_mb(cpu);
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index a162f859dd32..4d71d4e8b5a8 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -74,26 +74,25 @@ EXPORT_SYMBOL_GPL(rcu_lock_map);
         .n_force_qs_ngp = 0, \
 }
 
-struct rcu_state rcu_state = RCU_STATE_INITIALIZER(rcu_state);
-DEFINE_PER_CPU(struct rcu_data, rcu_data);
+struct rcu_state rcu_sched_state = RCU_STATE_INITIALIZER(rcu_sched_state);
+DEFINE_PER_CPU(struct rcu_data, rcu_sched_data);
 
 struct rcu_state rcu_bh_state = RCU_STATE_INITIALIZER(rcu_bh_state);
 DEFINE_PER_CPU(struct rcu_data, rcu_bh_data);
 
 /*
- * Increment the quiescent state counter.
- * The counter is a bit degenerated: We do not need to know
+ * 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. Thus just a flag.
+ * one since the start of the grace period, this just sets a flag.
  */
-void rcu_qsctr_inc(int cpu)
+void rcu_sched_qs(int cpu)
 {
-        struct rcu_data *rdp = &per_cpu(rcu_data, cpu);
+        struct rcu_data *rdp = &per_cpu(rcu_sched_data, cpu);
         rdp->passed_quiesc = 1;
         rdp->passed_quiesc_completed = rdp->completed;
 }
 
-void rcu_bh_qsctr_inc(int cpu)
+void rcu_bh_qs(int cpu)
 {
         struct rcu_data *rdp = &per_cpu(rcu_bh_data, cpu);
         rdp->passed_quiesc = 1;
@@ -114,11 +113,21 @@ static int qlowmark = 100;	/* Once only this many pending, use blimit. */
 static void force_quiescent_state(struct rcu_state *rsp, int relaxed);
 
 /*
+ * Return the number of RCU-sched batches processed thus far for debug & stats.
+ */
+long rcu_batches_completed_sched(void)
+{
+        return rcu_sched_state.completed;
+}
+EXPORT_SYMBOL_GPL(rcu_batches_completed_sched);
+
+/*
  * Return the number of RCU batches processed thus far for debug & stats.
+ * @@@ placeholder, maps to rcu_batches_completed_sched().
  */
 long rcu_batches_completed(void)
 {
-        return rcu_state.completed;
+        return rcu_batches_completed_sched();
 }
 EXPORT_SYMBOL_GPL(rcu_batches_completed);
 
@@ -310,7 +319,7 @@ void rcu_irq_exit(void)
         WARN_ON_RATELIMIT(rdtp->dynticks & 0x1, &rcu_rs);
 
         /* If the interrupt queued a callback, get out of dyntick mode. */
-        if (__get_cpu_var(rcu_data).nxtlist ||
+        if (__get_cpu_var(rcu_sched_data).nxtlist ||
             __get_cpu_var(rcu_bh_data).nxtlist)
                 set_need_resched();
 }
@@ -847,7 +856,7 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
         /*
          * Move callbacks from the outgoing CPU to the running CPU.
          * Note that the outgoing CPU is now quiscent, so it is now
-         * (uncharacteristically) safe to access it rcu_data structure.
+         * (uncharacteristically) safe to access its rcu_data structure.
          * Note also that we must carefully retain the order of the
          * outgoing CPU's callbacks in order for rcu_barrier() to work
          * correctly.  Finally, note that we start all the callbacks
@@ -878,7 +887,7 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
  */
 static void rcu_offline_cpu(int cpu)
 {
-        __rcu_offline_cpu(cpu, &rcu_state);
+        __rcu_offline_cpu(cpu, &rcu_sched_state);
         __rcu_offline_cpu(cpu, &rcu_bh_state);
 }
 
@@ -973,17 +982,16 @@ void rcu_check_callbacks(int cpu, int user)
                  * Get here if this CPU took its interrupt from user
                  * mode or from the idle loop, and if this is not a
                  * nested interrupt.  In this case, the CPU is in
-                 * a quiescent state, so count it.
+                 * a quiescent state, so note it.
                  *
                  * No memory barrier is required here because both
-                 * rcu_qsctr_inc() and rcu_bh_qsctr_inc() reference
-                 * only CPU-local variables that other CPUs neither
-                 * access nor modify, at least not while the corresponding
-                 * CPU is online.
+                 * rcu_sched_qs() and rcu_bh_qs() reference only CPU-local
+                 * variables that other CPUs neither access nor modify,
+                 * at least not while the corresponding CPU is online.
                  */
 
-                rcu_qsctr_inc(cpu);
-                rcu_bh_qsctr_inc(cpu);
+                rcu_sched_qs(cpu);
+                rcu_bh_qs(cpu);
 
         } else if (!in_softirq()) {
 
@@ -991,10 +999,10 @@ void rcu_check_callbacks(int cpu, int user)
                  * Get here if this CPU did not take its interrupt from
                  * softirq, in other words, if it is not interrupting
                  * a rcu_bh read-side critical section.  This is an _bh
-                 * critical section, so count it.
+                 * critical section, so note it.
                  */
 
-                rcu_bh_qsctr_inc(cpu);
+                rcu_bh_qs(cpu);
         }
         raise_softirq(RCU_SOFTIRQ);
 }
@@ -1174,7 +1182,8 @@ static void rcu_process_callbacks(struct softirq_action *unused)
          */
         smp_mb(); /* See above block comment. */
 
-        __rcu_process_callbacks(&rcu_state, &__get_cpu_var(rcu_data));
+        __rcu_process_callbacks(&rcu_sched_state,
+                                &__get_cpu_var(rcu_sched_data));
         __rcu_process_callbacks(&rcu_bh_state, &__get_cpu_var(rcu_bh_data));
 
         /*
@@ -1231,14 +1240,25 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu),
 }
 
 /*
- * Queue an RCU callback for invocation after a grace period.
+ * Queue an RCU-sched callback for invocation after a grace period.
+ */
+void call_rcu_sched(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
+{
+        __call_rcu(head, func, &rcu_sched_state);
+}
+EXPORT_SYMBOL_GPL(call_rcu_sched);
+
+/*
+ * @@@ Queue an RCU callback for invocation after a grace period.
+ * @@@ Placeholder pending rcutree_plugin.h.
  */
 void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
 {
-        __call_rcu(head, func, &rcu_state);
+        call_rcu_sched(head, func);
 }
 EXPORT_SYMBOL_GPL(call_rcu);
 
+
 /*
  * Queue an RCU for invocation after a quicker grace period.
  */
@@ -1311,7 +1331,7 @@ static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp)
  */
 int rcu_pending(int cpu)
 {
-        return __rcu_pending(&rcu_state, &per_cpu(rcu_data, cpu)) ||
+        return __rcu_pending(&rcu_sched_state, &per_cpu(rcu_sched_data, cpu)) ||
                __rcu_pending(&rcu_bh_state, &per_cpu(rcu_bh_data, cpu));
 }
 
@@ -1324,7 +1344,7 @@ int rcu_pending(int cpu)
 int rcu_needs_cpu(int cpu)
 {
         /* RCU callbacks either ready or pending? */
-        return per_cpu(rcu_data, cpu).nxtlist ||
+        return per_cpu(rcu_sched_data, cpu).nxtlist ||
                per_cpu(rcu_bh_data, cpu).nxtlist;
 }
 
@@ -1418,7 +1438,7 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
 
 static void __cpuinit rcu_online_cpu(int cpu)
 {
-        rcu_init_percpu_data(cpu, &rcu_state);
+        rcu_init_percpu_data(cpu, &rcu_sched_state);
         rcu_init_percpu_data(cpu, &rcu_bh_state);
 }
 
@@ -1545,10 +1565,10 @@ void __init __rcu_init(void)
 #ifdef CONFIG_RCU_CPU_STALL_DETECTOR
         printk(KERN_INFO "RCU-based detection of stalled CPUs is enabled.\n");
 #endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
-        rcu_init_one(&rcu_state);
-        RCU_DATA_PTR_INIT(&rcu_state, rcu_data);
+        rcu_init_one(&rcu_sched_state);
+        RCU_DATA_PTR_INIT(&rcu_sched_state, rcu_sched_data);
         for_each_possible_cpu(i)
-                rcu_boot_init_percpu_data(i, &rcu_state);
+                rcu_boot_init_percpu_data(i, &rcu_sched_state);
         rcu_init_one(&rcu_bh_state);
         RCU_DATA_PTR_INIT(&rcu_bh_state, rcu_bh_data);
         for_each_possible_cpu(i)
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index 7cc830a1c44a..0024e5ddcc68 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -238,8 +238,8 @@ struct rcu_state {
 /*
  * RCU implementation internal declarations:
  */
-extern struct rcu_state rcu_state;
-DECLARE_PER_CPU(struct rcu_data, rcu_data);
+extern struct rcu_state rcu_sched_state;
+DECLARE_PER_CPU(struct rcu_data, rcu_sched_data);
 
 extern struct rcu_state rcu_bh_state;
 DECLARE_PER_CPU(struct rcu_data, rcu_bh_data);
diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c
index 0cb52b887758..236c0504fee2 100644
--- a/kernel/rcutree_trace.c
+++ b/kernel/rcutree_trace.c
@@ -77,8 +77,8 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
 
 static int show_rcudata(struct seq_file *m, void *unused)
 {
-        seq_puts(m, "rcu:\n");
-        PRINT_RCU_DATA(rcu_data, print_one_rcu_data, m);
+        seq_puts(m, "rcu_sched:\n");
+        PRINT_RCU_DATA(rcu_sched_data, print_one_rcu_data, m);
         seq_puts(m, "rcu_bh:\n");
         PRINT_RCU_DATA(rcu_bh_data, print_one_rcu_data, m);
         return 0;
@@ -125,8 +125,8 @@ static int show_rcudata_csv(struct seq_file *m, void *unused)
         seq_puts(m, "\"dt\",\"dt nesting\",\"dn\",\"df\",");
 #endif /* #ifdef CONFIG_NO_HZ */
         seq_puts(m, "\"of\",\"ri\",\"ql\",\"b\"\n");
-        seq_puts(m, "\"rcu:\"\n");
-        PRINT_RCU_DATA(rcu_data, print_one_rcu_data_csv, m);
+        seq_puts(m, "\"rcu_sched:\"\n");
+        PRINT_RCU_DATA(rcu_sched_data, print_one_rcu_data_csv, m);
         seq_puts(m, "\"rcu_bh:\"\n");
         PRINT_RCU_DATA(rcu_bh_data, print_one_rcu_data_csv, m);
         return 0;
@@ -172,8 +172,8 @@ static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp)
 
 static int show_rcuhier(struct seq_file *m, void *unused)
 {
-        seq_puts(m, "rcu:\n");
-        print_one_rcu_state(m, &rcu_state);
+        seq_puts(m, "rcu_sched:\n");
+        print_one_rcu_state(m, &rcu_sched_state);
         seq_puts(m, "rcu_bh:\n");
         print_one_rcu_state(m, &rcu_bh_state);
         return 0;
@@ -194,8 +194,8 @@ static struct file_operations rcuhier_fops = {
 
 static int show_rcugp(struct seq_file *m, void *unused)
 {
-        seq_printf(m, "rcu: completed=%ld  gpnum=%ld\n",
-                   rcu_state.completed, rcu_state.gpnum);
+        seq_printf(m, "rcu_sched: completed=%ld  gpnum=%ld\n",
+                   rcu_sched_state.completed, rcu_sched_state.gpnum);
         seq_printf(m, "rcu_bh: completed=%ld  gpnum=%ld\n",
                    rcu_bh_state.completed, rcu_bh_state.gpnum);
         return 0;
@@ -244,8 +244,8 @@ static void print_rcu_pendings(struct seq_file *m, struct rcu_state *rsp)
 
 static int show_rcu_pending(struct seq_file *m, void *unused)
 {
-        seq_puts(m, "rcu:\n");
-        print_rcu_pendings(m, &rcu_state);
+        seq_puts(m, "rcu_sched:\n");
+        print_rcu_pendings(m, &rcu_sched_state);
         seq_puts(m, "rcu_bh:\n");
         print_rcu_pendings(m, &rcu_bh_state);
         return 0;
diff --git a/kernel/sched.c b/kernel/sched.c
index cda8b81f8801..c9beca67a53e 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -5325,7 +5325,7 @@ need_resched:
         preempt_disable();
         cpu = smp_processor_id();
         rq = cpu_rq(cpu);
-        rcu_qsctr_inc(cpu);
+        rcu_sched_qs(cpu);
         prev = rq->curr;
         switch_count = &prev->nivcsw;
 
diff --git a/kernel/softirq.c b/kernel/softirq.c
index eb5e131a0485..7db25067cd2d 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -227,7 +227,7 @@ restart:
                                 preempt_count() = prev_count;
                         }
 
-                        rcu_bh_qsctr_inc(cpu);
+                        rcu_bh_qs(cpu);
                 }
                 h++;
                 pending >>= 1;
@@ -721,7 +721,7 @@ static int ksoftirqd(void * __bind_cpu)
                         preempt_enable_no_resched();
                         cond_resched();
                         preempt_disable();
-                        rcu_qsctr_inc((long)__bind_cpu);
+                        rcu_sched_qs((long)__bind_cpu);
                 }
                 preempt_enable();
                 set_current_state(TASK_INTERRUPTIBLE);