rcu: Remove RCU CPU stall warnings from Tiny RCU

Tiny RCU's job is to be tiny, so this commit removes its RCU CPU
stall warning code.  After this, there is no longer any need for
rcu_sched_ctrlblk and rcu_bh_ctrlblk to be in tiny_plugin.h, so this
commit also moves them to tiny.c.

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

1 files changed, 18 insertions, 17 deletions

diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c
index 595cb1bf944f..f8488965250f 100644
--- a/kernel/rcu/tiny.c
+++ b/kernel/rcu/tiny.c
@@ -38,11 +38,23 @@
 
 #include "rcu.h"
 
-/* Forward declarations for tiny_plugin.h. */
-struct rcu_ctrlblk;
-static void __call_rcu(struct rcu_head *head,
-                       rcu_callback_t func,
-                       struct rcu_ctrlblk *rcp);
+/* Global control variables for rcupdate callback mechanism. */
+struct rcu_ctrlblk {
+        struct rcu_head *rcucblist;     /* List of pending callbacks (CBs). */
+        struct rcu_head **donetail;     /* ->next pointer of last "done" CB. */
+        struct rcu_head **curtail;      /* ->next pointer of last CB. */
+};
+
+/* Definition for rcupdate control block. */
+static struct rcu_ctrlblk rcu_sched_ctrlblk = {
+        .donetail       = &rcu_sched_ctrlblk.rcucblist,
+        .curtail        = &rcu_sched_ctrlblk.rcucblist,
+};
+
+static struct rcu_ctrlblk rcu_bh_ctrlblk = {
+        .donetail       = &rcu_bh_ctrlblk.rcucblist,
+        .curtail        = &rcu_bh_ctrlblk.rcucblist,
+};
 
 #include "tiny_plugin.h"
 
@@ -65,7 +77,6 @@ EXPORT_SYMBOL(rcu_barrier_sched);
  */
 static int rcu_qsctr_help(struct rcu_ctrlblk *rcp)
 {
-        RCU_TRACE(reset_cpu_stall_ticks(rcp);)
         if (rcp->donetail != rcp->curtail) {
                 rcp->donetail = rcp->curtail;
                 return 1;
@@ -111,7 +122,6 @@ void rcu_bh_qs(void)
  */
 void rcu_check_callbacks(int user)
 {
-        RCU_TRACE(check_cpu_stalls();)
         if (user)
                 rcu_sched_qs();
         else if (!in_softirq())
@@ -126,10 +136,8 @@ void rcu_check_callbacks(int user)
  */
 static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp)
 {
-        const char *rn = NULL;
         struct rcu_head *next, *list;
         unsigned long flags;
-        RCU_TRACE(int cb_count = 0;)
 
         /* Move the ready-to-invoke callbacks to a local list. */
         local_irq_save(flags);
@@ -147,18 +155,15 @@ static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp)
         local_irq_restore(flags);
 
         /* Invoke the callbacks on the local list. */
-        RCU_TRACE(rn = rcp->name;)
         while (list) {
                 next = list->next;
                 prefetch(next);
                 debug_rcu_head_unqueue(list);
                 local_bh_disable();
-                __rcu_reclaim(rn, list);
+                __rcu_reclaim("", list);
                 local_bh_enable();
                 list = next;
-                RCU_TRACE(cb_count++;)
         }
-        RCU_TRACE(rcu_trace_sub_qlen(rcp, cb_count);)
 }
 
 static __latent_entropy void rcu_process_callbacks(struct softirq_action *unused)
@@ -202,7 +207,6 @@ static void __call_rcu(struct rcu_head *head,
         local_irq_save(flags);
         *rcp->curtail = head;
         rcp->curtail = &head->next;
-        RCU_TRACE(rcp->qlen++;)
         local_irq_restore(flags);
 
         if (unlikely(is_idle_task(current))) {
@@ -235,8 +239,5 @@ EXPORT_SYMBOL_GPL(call_rcu_bh);
 void __init rcu_init(void)
 {
         open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
-        RCU_TRACE(reset_cpu_stall_ticks(&rcu_sched_ctrlblk);)
-        RCU_TRACE(reset_cpu_stall_ticks(&rcu_bh_ctrlblk);)
-
         rcu_early_boot_tests();
 }