Merge tag 'rcu-fixes-v6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic...

[linux-2.6-block.git] / kernel / rcu / tree.c

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index d3a97e1290203f8a00c4dc97fa0087676926b08e..3ac3c846105fb4c059a001ae3cf52a3c7747aac5 100644 (file)
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -755,14 +755,19 @@ static int dyntick_save_progress_counter(struct rcu_data *rdp)
 }
 
 /*
- * Return true if the specified CPU has passed through a quiescent
- * state by virtue of being in or having passed through an dynticks
- * idle state since the last call to dyntick_save_progress_counter()
- * for this same CPU, or by virtue of having been offline.
+ * Returns positive if the specified CPU has passed through a quiescent state
+ * by virtue of being in or having passed through an dynticks idle state since
+ * the last call to dyntick_save_progress_counter() for this same CPU, or by
+ * virtue of having been offline.
+ *
+ * Returns negative if the specified CPU needs a force resched.
+ *
+ * Returns zero otherwise.
  */
 static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
 {
        unsigned long jtsq;
+       int ret = 0;
        struct rcu_node *rnp = rdp->mynode;
 
        /*
@@ -848,8 +853,8 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
            (time_after(jiffies, READ_ONCE(rdp->last_fqs_resched) + jtsq * 3) ||
             rcu_state.cbovld)) {
                WRITE_ONCE(rdp->rcu_urgent_qs, true);
-               resched_cpu(rdp->cpu);
                WRITE_ONCE(rdp->last_fqs_resched, jiffies);
+               ret = -1;
        }
 
        /*
@@ -862,8 +867,8 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
        if (time_after(jiffies, rcu_state.jiffies_resched)) {
                if (time_after(jiffies,
                               READ_ONCE(rdp->last_fqs_resched) + jtsq)) {
-                       resched_cpu(rdp->cpu);
                        WRITE_ONCE(rdp->last_fqs_resched, jiffies);
+                       ret = -1;
                }
                if (IS_ENABLED(CONFIG_IRQ_WORK) &&
                    !rdp->rcu_iw_pending && rdp->rcu_iw_gp_seq != rnp->gp_seq &&
@@ -892,7 +897,7 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
                }
        }
 
-       return 0;
+       return ret;
 }
 
 /* Trace-event wrapper function for trace_rcu_future_grace_period.  */
@@ -2271,15 +2276,15 @@ static void force_qs_rnp(int (*f)(struct rcu_data *rdp))
 {
        int cpu;
        unsigned long flags;
-       unsigned long mask;
-       struct rcu_data *rdp;
        struct rcu_node *rnp;
 
        rcu_state.cbovld = rcu_state.cbovldnext;
        rcu_state.cbovldnext = false;
        rcu_for_each_leaf_node(rnp) {
+               unsigned long mask = 0;
+               unsigned long rsmask = 0;
+
                cond_resched_tasks_rcu_qs();
-               mask = 0;
                raw_spin_lock_irqsave_rcu_node(rnp, flags);
                rcu_state.cbovldnext |= !!rnp->cbovldmask;
                if (rnp->qsmask == 0) {
@@ -2297,11 +2302,17 @@ static void force_qs_rnp(int (*f)(struct rcu_data *rdp))
                        continue;
                }
                for_each_leaf_node_cpu_mask(rnp, cpu, rnp->qsmask) {
+                       struct rcu_data *rdp;
+                       int ret;
+
                        rdp = per_cpu_ptr(&rcu_data, cpu);
-                       if (f(rdp)) {
+                       ret = f(rdp);
+                       if (ret > 0) {
                                mask |= rdp->grpmask;
                                rcu_disable_urgency_upon_qs(rdp);
                        }
+                       if (ret < 0)
+                               rsmask |= rdp->grpmask;
                }
                if (mask != 0) {
                        /* Idle/offline CPUs, report (releases rnp->lock). */
@@ -2310,6 +2321,9 @@ static void force_qs_rnp(int (*f)(struct rcu_data *rdp))
                        /* Nothing to do here, so just drop the lock. */
                        raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
                }
+
+               for_each_leaf_node_cpu_mask(rnp, cpu, rsmask)
+                       resched_cpu(cpu);
        }
 }
 
@@ -4195,6 +4209,13 @@ static bool rcu_rdp_cpu_online(struct rcu_data *rdp)
        return !!(rdp->grpmask & rcu_rnp_online_cpus(rdp->mynode));
 }
 
+bool rcu_cpu_online(int cpu)
+{
+       struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
+
+       return rcu_rdp_cpu_online(rdp);
+}
+
 #if defined(CONFIG_PROVE_RCU) && defined(CONFIG_HOTPLUG_CPU)
 
 /*