1 files changed, 59 insertions, 52 deletions

diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index c1d7f27bd38f..3ec85cb5d544 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -30,14 +30,24 @@
 #include <linux/smpboot.h>
 #include "../time/tick-internal.h"
 
-#define RCU_KTHREAD_PRIO 1
-
 #ifdef CONFIG_RCU_BOOST
+
 #include "../locking/rtmutex_common.h"
-#define RCU_BOOST_PRIO CONFIG_RCU_BOOST_PRIO
-#else
-#define RCU_BOOST_PRIO RCU_KTHREAD_PRIO
-#endif
+
+/* rcuc/rcub kthread realtime priority */
+static int kthread_prio = CONFIG_RCU_KTHREAD_PRIO;
+module_param(kthread_prio, int, 0644);
+
+/*
+ * Control variables for per-CPU and per-rcu_node kthreads.  These
+ * handle all flavors of RCU.
+ */
+static DEFINE_PER_CPU(struct task_struct *, rcu_cpu_kthread_task);
+DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_status);
+DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_loops);
+DEFINE_PER_CPU(char, rcu_cpu_has_work);
+
+#endif /* #ifdef CONFIG_RCU_BOOST */
 
 #ifdef CONFIG_RCU_NOCB_CPU
 static cpumask_var_t rcu_nocb_mask; /* CPUs to have callbacks offloaded. */
@@ -72,9 +82,6 @@ static void __init rcu_bootup_announce_oddness(void)
 #ifdef CONFIG_RCU_TORTURE_TEST_RUNNABLE
         pr_info("\tRCU torture testing starts during boot.\n");
 #endif
-#if defined(CONFIG_TREE_PREEMPT_RCU) && !defined(CONFIG_RCU_CPU_STALL_VERBOSE)
-        pr_info("\tDump stacks of tasks blocking RCU-preempt GP.\n");
-#endif
 #if defined(CONFIG_RCU_CPU_STALL_INFO)
         pr_info("\tAdditional per-CPU info printed with stalls.\n");
 #endif
@@ -85,9 +92,12 @@ static void __init rcu_bootup_announce_oddness(void)
                 pr_info("\tBoot-time adjustment of leaf fanout to %d.\n", rcu_fanout_leaf);
         if (nr_cpu_ids != NR_CPUS)
                 pr_info("\tRCU restricting CPUs from NR_CPUS=%d to nr_cpu_ids=%d.\n", NR_CPUS, nr_cpu_ids);
+#ifdef CONFIG_RCU_BOOST
+        pr_info("\tRCU kthread priority: %d.\n", kthread_prio);
+#endif
 }
 
-#ifdef CONFIG_TREE_PREEMPT_RCU
+#ifdef CONFIG_PREEMPT_RCU
 
 RCU_STATE_INITIALIZER(rcu_preempt, 'p', call_rcu);
 static struct rcu_state *rcu_state_p = &rcu_preempt_state;
@@ -156,7 +166,7 @@ static void rcu_preempt_qs(void)
  *
  * Caller must disable preemption.
  */
-static void rcu_preempt_note_context_switch(int cpu)
+static void rcu_preempt_note_context_switch(void)
 {
         struct task_struct *t = current;
         unsigned long flags;
@@ -167,7 +177,7 @@ static void rcu_preempt_note_context_switch(int cpu)
             !t->rcu_read_unlock_special.b.blocked) {
 
                 /* Possibly blocking in an RCU read-side critical section. */
-                rdp = per_cpu_ptr(rcu_preempt_state.rda, cpu);
+                rdp = this_cpu_ptr(rcu_preempt_state.rda);
                 rnp = rdp->mynode;
                 raw_spin_lock_irqsave(&rnp->lock, flags);
                 smp_mb__after_unlock_lock();
@@ -415,8 +425,6 @@ void rcu_read_unlock_special(struct task_struct *t)
         }
 }
 
-#ifdef CONFIG_RCU_CPU_STALL_VERBOSE
-
 /*
  * Dump detailed information for all tasks blocking the current RCU
  * grace period on the specified rcu_node structure.
@@ -451,14 +459,6 @@ static void rcu_print_detail_task_stall(struct rcu_state *rsp)
                 rcu_print_detail_task_stall_rnp(rnp);
 }
 
-#else /* #ifdef CONFIG_RCU_CPU_STALL_VERBOSE */
-
-static void rcu_print_detail_task_stall(struct rcu_state *rsp)
-{
-}
-
-#endif /* #else #ifdef CONFIG_RCU_CPU_STALL_VERBOSE */
-
 #ifdef CONFIG_RCU_CPU_STALL_INFO
 
 static void rcu_print_task_stall_begin(struct rcu_node *rnp)
@@ -621,7 +621,7 @@ static int rcu_preempt_offline_tasks(struct rcu_state *rsp,
  *
  * Caller must disable hard irqs.
  */
-static void rcu_preempt_check_callbacks(int cpu)
+static void rcu_preempt_check_callbacks(void)
 {
         struct task_struct *t = current;
 
@@ -630,8 +630,8 @@ static void rcu_preempt_check_callbacks(int cpu)
                 return;
         }
         if (t->rcu_read_lock_nesting > 0 &&
-            per_cpu(rcu_preempt_data, cpu).qs_pending &&
-            !per_cpu(rcu_preempt_data, cpu).passed_quiesce)
+            __this_cpu_read(rcu_preempt_data.qs_pending) &&
+            !__this_cpu_read(rcu_preempt_data.passed_quiesce))
                 t->rcu_read_unlock_special.b.need_qs = true;
 }
 
@@ -919,7 +919,7 @@ void exit_rcu(void)
         __rcu_read_unlock();
 }
 
-#else /* #ifdef CONFIG_TREE_PREEMPT_RCU */
+#else /* #ifdef CONFIG_PREEMPT_RCU */
 
 static struct rcu_state *rcu_state_p = &rcu_sched_state;
 
@@ -945,7 +945,7 @@ EXPORT_SYMBOL_GPL(rcu_batches_completed);
  * Because preemptible RCU does not exist, we never have to check for
  * CPUs being in quiescent states.
  */
-static void rcu_preempt_note_context_switch(int cpu)
+static void rcu_preempt_note_context_switch(void)
 {
 }
 
@@ -1017,7 +1017,7 @@ static int rcu_preempt_offline_tasks(struct rcu_state *rsp,
  * Because preemptible RCU does not exist, it never has any callbacks
  * to check.
  */
-static void rcu_preempt_check_callbacks(int cpu)
+static void rcu_preempt_check_callbacks(void)
 {
 }
 
@@ -1070,7 +1070,7 @@ void exit_rcu(void)
 {
 }
 
-#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
+#endif /* #else #ifdef CONFIG_PREEMPT_RCU */
 
 #ifdef CONFIG_RCU_BOOST
 
@@ -1326,7 +1326,7 @@ static int rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
         smp_mb__after_unlock_lock();
         rnp->boost_kthread_task = t;
         raw_spin_unlock_irqrestore(&rnp->lock, flags);
-        sp.sched_priority = RCU_BOOST_PRIO;
+        sp.sched_priority = kthread_prio;
         sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
         wake_up_process(t); /* get to TASK_INTERRUPTIBLE quickly. */
         return 0;
@@ -1343,7 +1343,7 @@ static void rcu_cpu_kthread_setup(unsigned int cpu)
 {
         struct sched_param sp;
 
-        sp.sched_priority = RCU_KTHREAD_PRIO;
+        sp.sched_priority = kthread_prio;
         sched_setscheduler_nocheck(current, SCHED_FIFO, &sp);
 }
 
@@ -1512,10 +1512,10 @@ static void rcu_prepare_kthreads(int cpu)
  * any flavor of RCU.
  */
 #ifndef CONFIG_RCU_NOCB_CPU_ALL
-int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies)
+int rcu_needs_cpu(unsigned long *delta_jiffies)
 {
         *delta_jiffies = ULONG_MAX;
-        return rcu_cpu_has_callbacks(cpu, NULL);
+        return rcu_cpu_has_callbacks(NULL);
 }
 #endif /* #ifndef CONFIG_RCU_NOCB_CPU_ALL */
 
@@ -1523,7 +1523,7 @@ int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies)
  * Because we do not have RCU_FAST_NO_HZ, don't bother cleaning up
  * after it.
  */
-static void rcu_cleanup_after_idle(int cpu)
+static void rcu_cleanup_after_idle(void)
 {
 }
 
@@ -1531,7 +1531,7 @@ static void rcu_cleanup_after_idle(int cpu)
  * Do the idle-entry grace-period work, which, because CONFIG_RCU_FAST_NO_HZ=n,
  * is nothing.
  */
-static void rcu_prepare_for_idle(int cpu)
+static void rcu_prepare_for_idle(void)
 {
 }
 
@@ -1624,15 +1624,15 @@ static bool __maybe_unused rcu_try_advance_all_cbs(void)
  * The caller must have disabled interrupts.
  */
 #ifndef CONFIG_RCU_NOCB_CPU_ALL
-int rcu_needs_cpu(int cpu, unsigned long *dj)
+int rcu_needs_cpu(unsigned long *dj)
 {
-        struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu);
+        struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
 
         /* Snapshot to detect later posting of non-lazy callback. */
         rdtp->nonlazy_posted_snap = rdtp->nonlazy_posted;
 
         /* If no callbacks, RCU doesn't need the CPU. */
-        if (!rcu_cpu_has_callbacks(cpu, &rdtp->all_lazy)) {
+        if (!rcu_cpu_has_callbacks(&rdtp->all_lazy)) {
                 *dj = ULONG_MAX;
                 return 0;
         }
@@ -1666,12 +1666,12 @@ int rcu_needs_cpu(int cpu, unsigned long *dj)
  *
  * The caller must have disabled interrupts.
  */
-static void rcu_prepare_for_idle(int cpu)
+static void rcu_prepare_for_idle(void)
 {
 #ifndef CONFIG_RCU_NOCB_CPU_ALL
         bool needwake;
         struct rcu_data *rdp;
-        struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu);
+        struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
         struct rcu_node *rnp;
         struct rcu_state *rsp;
         int tne;
@@ -1679,7 +1679,7 @@ static void rcu_prepare_for_idle(int cpu)
         /* Handle nohz enablement switches conservatively. */
         tne = ACCESS_ONCE(tick_nohz_active);
         if (tne != rdtp->tick_nohz_enabled_snap) {
-                if (rcu_cpu_has_callbacks(cpu, NULL))
+                if (rcu_cpu_has_callbacks(NULL))
                         invoke_rcu_core(); /* force nohz to see update. */
                 rdtp->tick_nohz_enabled_snap = tne;
                 return;
@@ -1688,7 +1688,7 @@ static void rcu_prepare_for_idle(int cpu)
                 return;
 
         /* If this is a no-CBs CPU, no callbacks, just return. */
-        if (rcu_is_nocb_cpu(cpu))
+        if (rcu_is_nocb_cpu(smp_processor_id()))
                 return;
 
         /*
@@ -1712,7 +1712,7 @@ static void rcu_prepare_for_idle(int cpu)
                 return;
         rdtp->last_accelerate = jiffies;
         for_each_rcu_flavor(rsp) {
-                rdp = per_cpu_ptr(rsp->rda, cpu);
+                rdp = this_cpu_ptr(rsp->rda);
                 if (!*rdp->nxttail[RCU_DONE_TAIL])
                         continue;
                 rnp = rdp->mynode;
@@ -1731,10 +1731,10 @@ static void rcu_prepare_for_idle(int cpu)
  * any grace periods that elapsed while the CPU was idle, and if any
  * callbacks are now ready to invoke, initiate invocation.
  */
-static void rcu_cleanup_after_idle(int cpu)
+static void rcu_cleanup_after_idle(void)
 {
 #ifndef CONFIG_RCU_NOCB_CPU_ALL
-        if (rcu_is_nocb_cpu(cpu))
+        if (rcu_is_nocb_cpu(smp_processor_id()))
                 return;
         if (rcu_try_advance_all_cbs())
                 invoke_rcu_core();
@@ -2573,9 +2573,13 @@ static void rcu_spawn_one_nocb_kthread(struct rcu_state *rsp, int cpu)
                         rdp->nocb_leader = rdp_spawn;
                         if (rdp_last && rdp != rdp_spawn)
                                 rdp_last->nocb_next_follower = rdp;
-                        rdp_last = rdp;
-                        rdp = rdp->nocb_next_follower;
-                        rdp_last->nocb_next_follower = NULL;
+                        if (rdp == rdp_spawn) {
+                                rdp = rdp->nocb_next_follower;
+                        } else {
+                                rdp_last = rdp;
+                                rdp = rdp->nocb_next_follower;
+                                rdp_last->nocb_next_follower = NULL;
+                        }
                 } while (rdp);
                 rdp_spawn->nocb_next_follower = rdp_old_leader;
         }
@@ -2761,9 +2765,10 @@ static int full_sysidle_state;		/* Current system-idle state. */
  * to detect full-system idle states, not RCU quiescent states and grace
  * periods.  The caller must have disabled interrupts.
  */
-static void rcu_sysidle_enter(struct rcu_dynticks *rdtp, int irq)
+static void rcu_sysidle_enter(int irq)
 {
         unsigned long j;
+        struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
 
         /* If there are no nohz_full= CPUs, no need to track this. */
         if (!tick_nohz_full_enabled())
@@ -2832,8 +2837,10 @@ void rcu_sysidle_force_exit(void)
  * usermode execution does -not- count as idle here!  The caller must
  * have disabled interrupts.
  */
-static void rcu_sysidle_exit(struct rcu_dynticks *rdtp, int irq)
+static void rcu_sysidle_exit(int irq)
 {
+        struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
+
         /* If there are no nohz_full= CPUs, no need to track this. */
         if (!tick_nohz_full_enabled())
                 return;
@@ -3127,11 +3134,11 @@ static void rcu_sysidle_init_percpu_data(struct rcu_dynticks *rdtp)
 
 #else /* #ifdef CONFIG_NO_HZ_FULL_SYSIDLE */
 
-static void rcu_sysidle_enter(struct rcu_dynticks *rdtp, int irq)
+static void rcu_sysidle_enter(int irq)
 {
 }
 
-static void rcu_sysidle_exit(struct rcu_dynticks *rdtp, int irq)
+static void rcu_sysidle_exit(int irq)
 {
 }