lockdep: Reduce stack_trace usage

[safe/jmp/linux-2.6] / kernel / rcutree_plugin.h

diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index ed241fc..79b53bd 100644 (file)
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -986,6 +986,7 @@ static void rcu_needs_cpu_flush(void)
 
 #define RCU_NEEDS_CPU_FLUSHES 5
 static DEFINE_PER_CPU(int, rcu_dyntick_drain);
+static DEFINE_PER_CPU(unsigned long, rcu_dyntick_holdoff);
 
 /*
  * Check to see if any future RCU-related work will need to be done
@@ -1009,10 +1010,15 @@ int rcu_needs_cpu(int cpu)
        int c = 0;
        int thatcpu;
 
+       /* Check for being in the holdoff period. */
+       if (per_cpu(rcu_dyntick_holdoff, cpu) == jiffies)
+               return rcu_needs_cpu_quick_check(cpu);
+
        /* Don't bother unless we are the last non-dyntick-idle CPU. */
        for_each_cpu_not(thatcpu, nohz_cpu_mask)
                if (thatcpu != cpu) {
                        per_cpu(rcu_dyntick_drain, cpu) = 0;
+                       per_cpu(rcu_dyntick_holdoff, cpu) = jiffies - 1;
                        return rcu_needs_cpu_quick_check(cpu);
                }
 
@@ -1022,6 +1028,7 @@ int rcu_needs_cpu(int cpu)
                per_cpu(rcu_dyntick_drain, cpu) = RCU_NEEDS_CPU_FLUSHES;
        } else if (--per_cpu(rcu_dyntick_drain, cpu) <= 0) {
                /* We have hit the limit, so time to give up. */
+               per_cpu(rcu_dyntick_holdoff, cpu) = jiffies;
                return rcu_needs_cpu_quick_check(cpu);
        }
 
@@ -1050,10 +1057,13 @@ int rcu_needs_cpu(int cpu)
 static void rcu_needs_cpu_flush(void)
 {
        int cpu = smp_processor_id();
+       unsigned long flags;
 
        if (per_cpu(rcu_dyntick_drain, cpu) <= 0)
                return;
+       local_irq_save(flags);
        (void)rcu_needs_cpu(cpu);
+       local_irq_restore(flags);
 }
 
 #endif /* #else #if !defined(CONFIG_RCU_FAST_NO_HZ) */