1 files changed, 13 insertions, 0 deletions

diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 08a765232432..506a7a97a2e2 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -204,6 +204,7 @@ static void rcu_preempt_note_context_switch(int cpu)
                 rdp = per_cpu_ptr(rcu_preempt_state.rda, cpu);
                 rnp = rdp->mynode;
                 raw_spin_lock_irqsave(&rnp->lock, flags);
+                smp_mb__after_unlock_lock();
                 t->rcu_read_unlock_special |= RCU_READ_UNLOCK_BLOCKED;
                 t->rcu_blocked_node = rnp;
 
@@ -312,6 +313,7 @@ static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp, unsigned long flags)
         mask = rnp->grpmask;
         raw_spin_unlock(&rnp->lock);    /* irqs remain disabled. */
         raw_spin_lock(&rnp_p->lock);    /* irqs already disabled. */
+        smp_mb__after_unlock_lock();
         rcu_report_qs_rnp(mask, &rcu_preempt_state, rnp_p, flags);
 }
 
@@ -381,6 +383,7 @@ void rcu_read_unlock_special(struct task_struct *t)
                 for (;;) {
                         rnp = t->rcu_blocked_node;
                         raw_spin_lock(&rnp->lock);  /* irqs already disabled. */
+                        smp_mb__after_unlock_lock();
                         if (rnp == t->rcu_blocked_node)
                                 break;
                         raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
@@ -605,6 +608,7 @@ static int rcu_preempt_offline_tasks(struct rcu_state *rsp,
         while (!list_empty(lp)) {
                 t = list_entry(lp->next, typeof(*t), rcu_node_entry);
                 raw_spin_lock(&rnp_root->lock); /* irqs already disabled */
+                smp_mb__after_unlock_lock();
                 list_del(&t->rcu_node_entry);
                 t->rcu_blocked_node = rnp_root;
                 list_add(&t->rcu_node_entry, lp_root);
@@ -629,6 +633,7 @@ static int rcu_preempt_offline_tasks(struct rcu_state *rsp,
          * in this case.
          */
         raw_spin_lock(&rnp_root->lock); /* irqs already disabled */
+        smp_mb__after_unlock_lock();
         if (rnp_root->boost_tasks != NULL &&
             rnp_root->boost_tasks != rnp_root->gp_tasks &&
             rnp_root->boost_tasks != rnp_root->exp_tasks)
@@ -772,6 +777,7 @@ static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,
         unsigned long mask;
 
         raw_spin_lock_irqsave(&rnp->lock, flags);
+        smp_mb__after_unlock_lock();
         for (;;) {
                 if (!sync_rcu_preempt_exp_done(rnp)) {
                         raw_spin_unlock_irqrestore(&rnp->lock, flags);
@@ -787,6 +793,7 @@ static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,
                 raw_spin_unlock(&rnp->lock); /* irqs remain disabled */
                 rnp = rnp->parent;
                 raw_spin_lock(&rnp->lock); /* irqs already disabled */
+                smp_mb__after_unlock_lock();
                 rnp->expmask &= ~mask;
         }
 }
@@ -806,6 +813,7 @@ sync_rcu_preempt_exp_init(struct rcu_state *rsp, struct rcu_node *rnp)
         int must_wait = 0;
 
         raw_spin_lock_irqsave(&rnp->lock, flags);
+        smp_mb__after_unlock_lock();
         if (list_empty(&rnp->blkd_tasks)) {
                 raw_spin_unlock_irqrestore(&rnp->lock, flags);
         } else {
@@ -886,6 +894,7 @@ void synchronize_rcu_expedited(void)
         /* Initialize ->expmask for all non-leaf rcu_node structures. */
         rcu_for_each_nonleaf_node_breadth_first(rsp, rnp) {
                 raw_spin_lock_irqsave(&rnp->lock, flags);
+                smp_mb__after_unlock_lock();
                 rnp->expmask = rnp->qsmaskinit;
                 raw_spin_unlock_irqrestore(&rnp->lock, flags);
         }
@@ -1191,6 +1200,7 @@ static int rcu_boost(struct rcu_node *rnp)
                 return 0;  /* Nothing left to boost. */
 
         raw_spin_lock_irqsave(&rnp->lock, flags);
+        smp_mb__after_unlock_lock();
 
         /*
          * Recheck under the lock: all tasks in need of boosting
@@ -1377,6 +1387,7 @@ static int rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
         if (IS_ERR(t))
                 return PTR_ERR(t);
         raw_spin_lock_irqsave(&rnp->lock, flags);
+        smp_mb__after_unlock_lock();
         rnp->boost_kthread_task = t;
         raw_spin_unlock_irqrestore(&rnp->lock, flags);
         sp.sched_priority = RCU_BOOST_PRIO;
@@ -1769,6 +1780,7 @@ static void rcu_prepare_for_idle(int cpu)
                         continue;
                 rnp = rdp->mynode;
                 raw_spin_lock(&rnp->lock); /* irqs already disabled. */
+                smp_mb__after_unlock_lock();
                 rcu_accelerate_cbs(rsp, rnp, rdp);
                 raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
         }
@@ -2209,6 +2221,7 @@ static void rcu_nocb_wait_gp(struct rcu_data *rdp)
         struct rcu_node *rnp = rdp->mynode;
 
         raw_spin_lock_irqsave(&rnp->lock, flags);
+        smp_mb__after_unlock_lock();
         c = rcu_start_future_gp(rnp, rdp);
         raw_spin_unlock_irqrestore(&rnp->lock, flags);