Merge tag 'gcc-plugins-v4.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git...

[cascardo/linux.git] / kernel / softirq.c

diff --git a/kernel/softirq.c b/kernel/softirq.c
index 34033fd..1bf81ef 100644 (file)
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -77,6 +77,17 @@ static void wakeup_softirqd(void)
                wake_up_process(tsk);
 }
 
+/*
+ * If ksoftirqd is scheduled, we do not want to process pending softirqs
+ * right now. Let ksoftirqd handle this at its own rate, to get fairness.
+ */
+static bool ksoftirqd_running(void)
+{
+       struct task_struct *tsk = __this_cpu_read(ksoftirqd);
+
+       return tsk && (tsk->state == TASK_RUNNING);
+}
+
 /*
  * preempt_count and SOFTIRQ_OFFSET usage:
  * - preempt_count is changed by SOFTIRQ_OFFSET on entering or leaving
@@ -313,7 +324,7 @@ asmlinkage __visible void do_softirq(void)
 
        pending = local_softirq_pending();
 
-       if (pending)
+       if (pending && !ksoftirqd_running())
                do_softirq_own_stack();
 
        local_irq_restore(flags);
@@ -340,6 +351,9 @@ void irq_enter(void)
 
 static inline void invoke_softirq(void)
 {
+       if (ksoftirqd_running())
+               return;
+
        if (!force_irqthreads) {
 #ifdef CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK
                /*
@@ -700,7 +714,7 @@ void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu)
        BUG();
 }
 
-static void takeover_tasklets(unsigned int cpu)
+static int takeover_tasklets(unsigned int cpu)
 {
        /* CPU is dead, so no lock needed. */
        local_irq_disable();
@@ -723,27 +737,12 @@ static void takeover_tasklets(unsigned int cpu)
        raise_softirq_irqoff(HI_SOFTIRQ);
 
        local_irq_enable();
+       return 0;
 }
+#else
+#define takeover_tasklets      NULL
 #endif /* CONFIG_HOTPLUG_CPU */
 
-static int cpu_callback(struct notifier_block *nfb, unsigned long action,
-                       void *hcpu)
-{
-       switch (action) {
-#ifdef CONFIG_HOTPLUG_CPU
-       case CPU_DEAD:
-       case CPU_DEAD_FROZEN:
-               takeover_tasklets((unsigned long)hcpu);
-               break;
-#endif /* CONFIG_HOTPLUG_CPU */
-       }
-       return NOTIFY_OK;
-}
-
-static struct notifier_block cpu_nfb = {
-       .notifier_call = cpu_callback
-};
-
 static struct smp_hotplug_thread softirq_threads = {
        .store                  = &ksoftirqd,
        .thread_should_run      = ksoftirqd_should_run,
@@ -753,8 +752,8 @@ static struct smp_hotplug_thread softirq_threads = {
 
 static __init int spawn_ksoftirqd(void)
 {
-       register_cpu_notifier(&cpu_nfb);
-
+       cpuhp_setup_state_nocalls(CPUHP_SOFTIRQ_DEAD, "softirq:dead", NULL,
+                                 takeover_tasklets);
        BUG_ON(smpboot_register_percpu_thread(&softirq_threads));
 
        return 0;