From: Thomas Gleixner <tglx@linutronix.de>
Date: Thu, 04 Oct 2012 14:20:47 +0100
Subject: softirq: Split softirq locks
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.9/older/patches-4.9.20-rt16.tar.xz

The 3.x RT series removed the split softirq implementation in favour
of pushing softirq processing into the context of the thread which
raised it. Though this prevents us from handling the various softirqs
at different priorities. Now instead of reintroducing the split
softirq threads we split the locks which serialize the softirq
processing.

If a softirq is raised in context of a thread, then the softirq is
noted on a per thread field, if the thread is in a bh disabled
region. If the softirq is raised from hard interrupt context, then the
bit is set in the flag field of ksoftirqd and ksoftirqd is invoked.
When a thread leaves a bh disabled region, then it tries to execute
the softirqs which have been raised in its own context. It acquires
the per softirq / per cpu lock for the softirq and then checks,
whether the softirq is still pending in the per cpu
local_softirq_pending() field. If yes, it runs the softirq. If no,
then some other task executed it already. This allows for zero config
softirq elevation in the context of user space tasks or interrupt
threads.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 include/linux/bottom_half.h |   34 +++
 include/linux/interrupt.h   |   15 +
 include/linux/preempt.h     |   15 +
 include/linux/sched.h       |    3 
 init/main.c                 |    1 
 kernel/softirq.c            |  492 +++++++++++++++++++++++++++++++++++++-------
 kernel/time/tick-sched.c    |    9 
 net/core/dev.c              |    6 
 8 files changed, 480 insertions(+), 95 deletions(-)

--- a/include/linux/bottom_half.h
+++ b/include/linux/bottom_half.h
@@ -3,6 +3,39 @@
 
 #include <linux/preempt.h>
 
+#ifdef CONFIG_PREEMPT_RT_FULL
+
+extern void __local_bh_disable(void);
+extern void _local_bh_enable(void);
+extern void __local_bh_enable(void);
+
+static inline void local_bh_disable(void)
+{
+	__local_bh_disable();
+}
+
+static inline void __local_bh_disable_ip(unsigned long ip, unsigned int cnt)
+{
+	__local_bh_disable();
+}
+
+static inline void local_bh_enable(void)
+{
+	__local_bh_enable();
+}
+
+static inline void __local_bh_enable_ip(unsigned long ip, unsigned int cnt)
+{
+	__local_bh_enable();
+}
+
+static inline void local_bh_enable_ip(unsigned long ip)
+{
+	__local_bh_enable();
+}
+
+#else
+
 #ifdef CONFIG_TRACE_IRQFLAGS
 extern void __local_bh_disable_ip(unsigned long ip, unsigned int cnt);
 #else
@@ -30,5 +63,6 @@ static inline void local_bh_enable(void)
 {
 	__local_bh_enable_ip(_THIS_IP_, SOFTIRQ_DISABLE_OFFSET);
 }
+#endif
 
 #endif /* _LINUX_BH_H */
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -469,10 +469,11 @@ struct softirq_action
 	void	(*action)(struct softirq_action *);
 };
 
+#ifndef CONFIG_PREEMPT_RT_FULL
 asmlinkage void do_softirq(void);
 asmlinkage void __do_softirq(void);
-
-#if defined(__ARCH_HAS_DO_SOFTIRQ) && !defined(CONFIG_PREEMPT_RT_FULL)
+static inline void thread_do_softirq(void) { do_softirq(); }
+#ifdef __ARCH_HAS_DO_SOFTIRQ
 void do_softirq_own_stack(void);
 #else
 static inline void do_softirq_own_stack(void)
@@ -480,6 +481,9 @@ static inline void do_softirq_own_stack(
 	__do_softirq();
 }
 #endif
+#else
+extern void thread_do_softirq(void);
+#endif
 
 extern void open_softirq(int nr, void (*action)(struct softirq_action *));
 extern void softirq_init(void);
@@ -487,6 +491,7 @@ extern void __raise_softirq_irqoff(unsig
 
 extern void raise_softirq_irqoff(unsigned int nr);
 extern void raise_softirq(unsigned int nr);
+extern void softirq_check_pending_idle(void);
 
 DECLARE_PER_CPU(struct task_struct *, ksoftirqd);
 
@@ -644,6 +649,12 @@ void tasklet_hrtimer_cancel(struct taskl
 	tasklet_kill(&ttimer->tasklet);
 }
 
+#ifdef CONFIG_PREEMPT_RT_FULL
+extern void softirq_early_init(void);
+#else
+static inline void softirq_early_init(void) { }
+#endif
+
 /*
  * Autoprobing for irqs:
  *
--- a/include/linux/preempt.h
+++ b/include/linux/preempt.h
@@ -50,7 +50,11 @@
 #define HARDIRQ_OFFSET	(1UL << HARDIRQ_SHIFT)
 #define NMI_OFFSET	(1UL << NMI_SHIFT)
 
-#define SOFTIRQ_DISABLE_OFFSET	(2 * SOFTIRQ_OFFSET)
+#ifndef CONFIG_PREEMPT_RT_FULL
+# define SOFTIRQ_DISABLE_OFFSET		(2 * SOFTIRQ_OFFSET)
+#else
+# define SOFTIRQ_DISABLE_OFFSET		(0)
+#endif
 
 /* We use the MSB mostly because its available */
 #define PREEMPT_NEED_RESCHED	0x80000000
@@ -59,9 +63,15 @@
 #include <asm/preempt.h>
 
 #define hardirq_count()	(preempt_count() & HARDIRQ_MASK)
-#define softirq_count()	(preempt_count() & SOFTIRQ_MASK)
 #define irq_count()	(preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK \
 				 | NMI_MASK))
+#ifndef CONFIG_PREEMPT_RT_FULL
+# define softirq_count()	(preempt_count() & SOFTIRQ_MASK)
+# define in_serving_softirq()	(softirq_count() & SOFTIRQ_OFFSET)
+#else
+# define softirq_count()	(0UL)
+extern int in_serving_softirq(void);
+#endif
 
 /*
  * Are we doing bottom half or hardware interrupt processing?
@@ -72,7 +82,6 @@
 #define in_irq()		(hardirq_count())
 #define in_softirq()		(softirq_count())
 #define in_interrupt()		(irq_count())
-#define in_serving_softirq()	(softirq_count() & SOFTIRQ_OFFSET)
 
 /*
  * Are we in NMI context?
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1965,6 +1965,8 @@ struct task_struct {
 #endif
 #ifdef CONFIG_PREEMPT_RT_BASE
 	struct rcu_head put_rcu;
+	int softirq_nestcnt;
+	unsigned int softirqs_raised;
 #endif
 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
 	unsigned long	task_state_change;
@@ -2281,6 +2283,7 @@ extern void thread_group_cputime_adjuste
 /*
  * Per process flags
  */
+#define PF_IN_SOFTIRQ	0x00000001	/* Task is serving softirq */
 #define PF_EXITING	0x00000004	/* getting shut down */
 #define PF_EXITPIDONE	0x00000008	/* pi exit done on shut down */
 #define PF_VCPU		0x00000010	/* I'm a virtual CPU */
--- a/init/main.c
+++ b/init/main.c
@@ -507,6 +507,7 @@ asmlinkage __visible void __init start_k
 	setup_command_line(command_line);
 	setup_nr_cpu_ids();
 	setup_per_cpu_areas();
+	softirq_early_init();
 	boot_cpu_state_init();
 	smp_prepare_boot_cpu();	/* arch-specific boot-cpu hooks */
 
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -26,6 +26,7 @@
 #include <linux/smp.h>
 #include <linux/smpboot.h>
 #include <linux/tick.h>
+#include <linux/locallock.h>
 #include <linux/irq.h>
 
 #define CREATE_TRACE_POINTS
@@ -63,6 +64,98 @@ const char * const softirq_to_name[NR_SO
 	"TASKLET", "SCHED", "HRTIMER", "RCU"
 };
 
+#ifdef CONFIG_NO_HZ_COMMON
+# ifdef CONFIG_PREEMPT_RT_FULL
+
+struct softirq_runner {
+	struct task_struct *runner[NR_SOFTIRQS];
+};
+
+static DEFINE_PER_CPU(struct softirq_runner, softirq_runners);
+
+static inline void softirq_set_runner(unsigned int sirq)
+{
+	struct softirq_runner *sr = this_cpu_ptr(&softirq_runners);
+
+	sr->runner[sirq] = current;
+}
+
+static inline void softirq_clr_runner(unsigned int sirq)
+{
+	struct softirq_runner *sr = this_cpu_ptr(&softirq_runners);
+
+	sr->runner[sirq] = NULL;
+}
+
+/*
+ * On preempt-rt a softirq running context might be blocked on a
+ * lock. There might be no other runnable task on this CPU because the
+ * lock owner runs on some other CPU. So we have to go into idle with
+ * the pending bit set. Therefor we need to check this otherwise we
+ * warn about false positives which confuses users and defeats the
+ * whole purpose of this test.
+ *
+ * This code is called with interrupts disabled.
+ */
+void softirq_check_pending_idle(void)
+{
+	static int rate_limit;
+	struct softirq_runner *sr = this_cpu_ptr(&softirq_runners);
+	u32 warnpending;
+	int i;
+
+	if (rate_limit >= 10)
+		return;
+
+	warnpending = local_softirq_pending() & SOFTIRQ_STOP_IDLE_MASK;
+	for (i = 0; i < NR_SOFTIRQS; i++) {
+		struct task_struct *tsk = sr->runner[i];
+
+		/*
+		 * The wakeup code in rtmutex.c wakes up the task
+		 * _before_ it sets pi_blocked_on to NULL under
+		 * tsk->pi_lock. So we need to check for both: state
+		 * and pi_blocked_on.
+		 */
+		if (tsk) {
+			raw_spin_lock(&tsk->pi_lock);
+			if (tsk->pi_blocked_on || tsk->state == TASK_RUNNING) {
+				/* Clear all bits pending in that task */
+				warnpending &= ~(tsk->softirqs_raised);
+				warnpending &= ~(1 << i);
+			}
+			raw_spin_unlock(&tsk->pi_lock);
+		}
+	}
+
+	if (warnpending) {
+		printk(KERN_ERR "NOHZ: local_softirq_pending %02x\n",
+		       warnpending);
+		rate_limit++;
+	}
+}
+# else
+/*
+ * On !PREEMPT_RT we just printk rate limited:
+ */
+void softirq_check_pending_idle(void)
+{
+	static int rate_limit;
+
+	if (rate_limit < 10 &&
+			(local_softirq_pending() & SOFTIRQ_STOP_IDLE_MASK)) {
+		printk(KERN_ERR "NOHZ: local_softirq_pending %02x\n",
+		       local_softirq_pending());
+		rate_limit++;
+	}
+}
+# endif
+
+#else /* !CONFIG_NO_HZ_COMMON */
+static inline void softirq_set_runner(unsigned int sirq) { }
+static inline void softirq_clr_runner(unsigned int sirq) { }
+#endif
+
 /*
  * we cannot loop indefinitely here to avoid userspace starvation,
  * but we also don't want to introduce a worst case 1/HZ latency
@@ -78,6 +171,26 @@ static void wakeup_softirqd(void)
 		wake_up_process(tsk);
 }
 
+static void handle_softirq(unsigned int vec_nr)
+{
+	struct softirq_action *h = softirq_vec + vec_nr;
+	int prev_count;
+
+	prev_count = preempt_count();
+
+	kstat_incr_softirqs_this_cpu(vec_nr);
+
+	trace_softirq_entry(vec_nr);
+	h->action(h);
+	trace_softirq_exit(vec_nr);
+	if (unlikely(prev_count != preempt_count())) {
+		pr_err("huh, entered softirq %u %s %p with preempt_count %08x, exited with %08x?\n",
+		       vec_nr, softirq_to_name[vec_nr], h->action,
+		       prev_count, preempt_count());
+		preempt_count_set(prev_count);
+	}
+}
+
 /*
  * 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.
@@ -89,6 +202,48 @@ static bool ksoftirqd_running(void)
 	return tsk && (tsk->state == TASK_RUNNING);
 }
 
+#ifndef CONFIG_PREEMPT_RT_FULL
+static inline int ksoftirqd_softirq_pending(void)
+{
+	return local_softirq_pending();
+}
+
+static void handle_pending_softirqs(u32 pending)
+{
+	struct softirq_action *h = softirq_vec;
+	int softirq_bit;
+
+	local_irq_enable();
+
+	h = softirq_vec;
+
+	while ((softirq_bit = ffs(pending))) {
+		unsigned int vec_nr;
+
+		h += softirq_bit - 1;
+		vec_nr = h - softirq_vec;
+		handle_softirq(vec_nr);
+
+		h++;
+		pending >>= softirq_bit;
+	}
+
+	rcu_bh_qs();
+	local_irq_disable();
+}
+
+static void run_ksoftirqd(unsigned int cpu)
+{
+	local_irq_disable();
+	if (ksoftirqd_softirq_pending()) {
+		__do_softirq();
+		local_irq_enable();
+		cond_resched_rcu_qs();
+		return;
+	}
+	local_irq_enable();
+}
+
 /*
  * preempt_count and SOFTIRQ_OFFSET usage:
  * - preempt_count is changed by SOFTIRQ_OFFSET on entering or leaving
@@ -244,10 +399,8 @@ asmlinkage __visible void __softirq_entr
 	unsigned long end = jiffies + MAX_SOFTIRQ_TIME;
 	unsigned long old_flags = current->flags;
 	int max_restart = MAX_SOFTIRQ_RESTART;
-	struct softirq_action *h;
 	bool in_hardirq;
 	__u32 pending;
-	int softirq_bit;
 
 	/*
 	 * Mask out PF_MEMALLOC s current task context is borrowed for the
@@ -266,36 +419,7 @@ asmlinkage __visible void __softirq_entr
 	/* Reset the pending bitmask before enabling irqs */
 	set_softirq_pending(0);
 
-	local_irq_enable();
-
-	h = softirq_vec;
-
-	while ((softirq_bit = ffs(pending))) {
-		unsigned int vec_nr;
-		int prev_count;
-
-		h += softirq_bit - 1;
-
-		vec_nr = h - softirq_vec;
-		prev_count = preempt_count();
-
-		kstat_incr_softirqs_this_cpu(vec_nr);
-
-		trace_softirq_entry(vec_nr);
-		h->action(h);
-		trace_softirq_exit(vec_nr);
-		if (unlikely(prev_count != preempt_count())) {
-			pr_err("huh, entered softirq %u %s %p with preempt_count %08x, exited with %08x?\n",
-			       vec_nr, softirq_to_name[vec_nr], h->action,
-			       prev_count, preempt_count());
-			preempt_count_set(prev_count);
-		}
-		h++;
-		pending >>= softirq_bit;
-	}
-
-	rcu_bh_qs();
-	local_irq_disable();
+	handle_pending_softirqs(pending);
 
 	pending = local_softirq_pending();
 	if (pending) {
@@ -332,6 +456,246 @@ asmlinkage __visible void do_softirq(voi
 }
 
 /*
+ * This function must run with irqs disabled!
+ */
+void raise_softirq_irqoff(unsigned int nr)
+{
+	__raise_softirq_irqoff(nr);
+
+	/*
+	 * If we're in an interrupt or softirq, we're done
+	 * (this also catches softirq-disabled code). We will
+	 * actually run the softirq once we return from
+	 * the irq or softirq.
+	 *
+	 * Otherwise we wake up ksoftirqd to make sure we
+	 * schedule the softirq soon.
+	 */
+	if (!in_interrupt())
+		wakeup_softirqd();
+}
+
+void __raise_softirq_irqoff(unsigned int nr)
+{
+	trace_softirq_raise(nr);
+	or_softirq_pending(1UL << nr);
+}
+
+static inline void local_bh_disable_nort(void) { local_bh_disable(); }
+static inline void _local_bh_enable_nort(void) { _local_bh_enable(); }
+static void ksoftirqd_set_sched_params(unsigned int cpu) { }
+static void ksoftirqd_clr_sched_params(unsigned int cpu, bool online) { }
+
+#else /* !PREEMPT_RT_FULL */
+
+/*
+ * On RT we serialize softirq execution with a cpu local lock per softirq
+ */
+static DEFINE_PER_CPU(struct local_irq_lock [NR_SOFTIRQS], local_softirq_locks);
+
+void __init softirq_early_init(void)
+{
+	int i;
+
+	for (i = 0; i < NR_SOFTIRQS; i++)
+		local_irq_lock_init(local_softirq_locks[i]);
+}
+
+static void lock_softirq(int which)
+{
+	local_lock(local_softirq_locks[which]);
+}
+
+static void unlock_softirq(int which)
+{
+	local_unlock(local_softirq_locks[which]);
+}
+
+static void do_single_softirq(int which)
+{
+	unsigned long old_flags = current->flags;
+
+	current->flags &= ~PF_MEMALLOC;
+	vtime_account_irq_enter(current);
+	current->flags |= PF_IN_SOFTIRQ;
+	lockdep_softirq_enter();
+	local_irq_enable();
+	handle_softirq(which);
+	local_irq_disable();
+	lockdep_softirq_exit();
+	current->flags &= ~PF_IN_SOFTIRQ;
+	vtime_account_irq_enter(current);
+	tsk_restore_flags(current, old_flags, PF_MEMALLOC);
+}
+
+/*
+ * Called with interrupts disabled. Process softirqs which were raised
+ * in current context (or on behalf of ksoftirqd).
+ */
+static void do_current_softirqs(void)
+{
+	while (current->softirqs_raised) {
+		int i = __ffs(current->softirqs_raised);
+		unsigned int pending, mask = (1U << i);
+
+		current->softirqs_raised &= ~mask;
+		local_irq_enable();
+
+		/*
+		 * If the lock is contended, we boost the owner to
+		 * process the softirq or leave the critical section
+		 * now.
+		 */
+		lock_softirq(i);
+		local_irq_disable();
+		softirq_set_runner(i);
+		/*
+		 * Check with the local_softirq_pending() bits,
+		 * whether we need to process this still or if someone
+		 * else took care of it.
+		 */
+		pending = local_softirq_pending();
+		if (pending & mask) {
+			set_softirq_pending(pending & ~mask);
+			do_single_softirq(i);
+		}
+		softirq_clr_runner(i);
+		unlock_softirq(i);
+		WARN_ON(current->softirq_nestcnt != 1);
+	}
+}
+
+void __local_bh_disable(void)
+{
+	if (++current->softirq_nestcnt == 1)
+		migrate_disable();
+}
+EXPORT_SYMBOL(__local_bh_disable);
+
+void __local_bh_enable(void)
+{
+	if (WARN_ON(current->softirq_nestcnt == 0))
+		return;
+
+	local_irq_disable();
+	if (current->softirq_nestcnt == 1 && current->softirqs_raised)
+		do_current_softirqs();
+	local_irq_enable();
+
+	if (--current->softirq_nestcnt == 0)
+		migrate_enable();
+}
+EXPORT_SYMBOL(__local_bh_enable);
+
+int in_serving_softirq(void)
+{
+	return current->flags & PF_IN_SOFTIRQ;
+}
+EXPORT_SYMBOL(in_serving_softirq);
+
+/* Called with preemption disabled */
+static void run_ksoftirqd(unsigned int cpu)
+{
+	local_irq_disable();
+	current->softirq_nestcnt++;
+
+	do_current_softirqs();
+	current->softirq_nestcnt--;
+	local_irq_enable();
+	cond_resched_rcu_qs();
+}
+
+/*
+ * Called from netif_rx_ni(). Preemption enabled, but migration
+ * disabled. So the cpu can't go away under us.
+ */
+void thread_do_softirq(void)
+{
+	if (!in_serving_softirq() && current->softirqs_raised) {
+		current->softirq_nestcnt++;
+		do_current_softirqs();
+		current->softirq_nestcnt--;
+	}
+}
+
+static void do_raise_softirq_irqoff(unsigned int nr)
+{
+	trace_softirq_raise(nr);
+	or_softirq_pending(1UL << nr);
+
+	/*
+	 * If we are not in a hard interrupt and inside a bh disabled
+	 * region, we simply raise the flag on current. local_bh_enable()
+	 * will make sure that the softirq is executed. Otherwise we
+	 * delegate it to ksoftirqd.
+	 */
+	if (!in_irq() && current->softirq_nestcnt)
+		current->softirqs_raised |= (1U << nr);
+	else if (__this_cpu_read(ksoftirqd))
+		__this_cpu_read(ksoftirqd)->softirqs_raised |= (1U << nr);
+}
+
+void __raise_softirq_irqoff(unsigned int nr)
+{
+	do_raise_softirq_irqoff(nr);
+	if (!in_irq() && !current->softirq_nestcnt)
+		wakeup_softirqd();
+}
+
+/*
+ * This function must run with irqs disabled!
+ */
+void raise_softirq_irqoff(unsigned int nr)
+{
+	do_raise_softirq_irqoff(nr);
+
+	/*
+	 * If we're in an hard interrupt we let irq return code deal
+	 * with the wakeup of ksoftirqd.
+	 */
+	if (in_irq())
+		return;
+	/*
+	 * If we are in thread context but outside of a bh disabled
+	 * region, we need to wake ksoftirqd as well.
+	 *
+	 * CHECKME: Some of the places which do that could be wrapped
+	 * into local_bh_disable/enable pairs. Though it's unclear
+	 * whether this is worth the effort. To find those places just
+	 * raise a WARN() if the condition is met.
+	 */
+	if (!current->softirq_nestcnt)
+		wakeup_softirqd();
+}
+
+static inline int ksoftirqd_softirq_pending(void)
+{
+	return current->softirqs_raised;
+}
+
+static inline void local_bh_disable_nort(void) { }
+static inline void _local_bh_enable_nort(void) { }
+
+static inline void ksoftirqd_set_sched_params(unsigned int cpu)
+{
+	struct sched_param param = { .sched_priority = 1 };
+
+	sched_setscheduler(current, SCHED_FIFO, &param);
+	/* Take over all pending softirqs when starting */
+	local_irq_disable();
+	current->softirqs_raised = local_softirq_pending();
+	local_irq_enable();
+}
+
+static inline void ksoftirqd_clr_sched_params(unsigned int cpu, bool online)
+{
+	struct sched_param param = { .sched_priority = 0 };
+
+	sched_setscheduler(current, SCHED_NORMAL, &param);
+}
+
+#endif /* PREEMPT_RT_FULL */
+/*
  * Enter an interrupt context.
  */
 void irq_enter(void)
@@ -342,9 +706,9 @@ void irq_enter(void)
 		 * Prevent raise_softirq from needlessly waking up ksoftirqd
 		 * here, as softirq will be serviced on return from interrupt.
 		 */
-		local_bh_disable();
+		local_bh_disable_nort();
 		tick_irq_enter();
-		_local_bh_enable();
+		_local_bh_enable_nort();
 	}
 
 	__irq_enter();
@@ -352,9 +716,13 @@ void irq_enter(void)
 
 static inline void invoke_softirq(void)
 {
+#ifdef CONFIG_PREEMPT_RT_FULL
+	unsigned long flags;
+#endif
+
 	if (ksoftirqd_running())
 		return;
-
+#ifndef CONFIG_PREEMPT_RT_FULL
 	if (!force_irqthreads) {
 #ifdef CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK
 		/*
@@ -374,6 +742,14 @@ static inline void invoke_softirq(void)
 	} else {
 		wakeup_softirqd();
 	}
+#else /* PREEMPT_RT_FULL */
+
+	local_irq_save(flags);
+	if (__this_cpu_read(ksoftirqd) &&
+			__this_cpu_read(ksoftirqd)->softirqs_raised)
+		wakeup_softirqd();
+	local_irq_restore(flags);
+#endif
 }
 
 static inline void tick_irq_exit(void)
@@ -410,26 +786,6 @@ void irq_exit(void)
 	trace_hardirq_exit(); /* must be last! */
 }
 
-/*
- * This function must run with irqs disabled!
- */
-inline void raise_softirq_irqoff(unsigned int nr)
-{
-	__raise_softirq_irqoff(nr);
-
-	/*
-	 * If we're in an interrupt or softirq, we're done
-	 * (this also catches softirq-disabled code). We will
-	 * actually run the softirq once we return from
-	 * the irq or softirq.
-	 *
-	 * Otherwise we wake up ksoftirqd to make sure we
-	 * schedule the softirq soon.
-	 */
-	if (!in_interrupt())
-		wakeup_softirqd();
-}
-
 void raise_softirq(unsigned int nr)
 {
 	unsigned long flags;
@@ -439,12 +795,6 @@ void raise_softirq(unsigned int nr)
 	local_irq_restore(flags);
 }
 
-void __raise_softirq_irqoff(unsigned int nr)
-{
-	trace_softirq_raise(nr);
-	or_softirq_pending(1UL << nr);
-}
-
 void open_softirq(int nr, void (*action)(struct softirq_action *))
 {
 	softirq_vec[nr].action = action;
@@ -747,23 +1097,7 @@ EXPORT_SYMBOL(tasklet_unlock_wait);
 
 static int ksoftirqd_should_run(unsigned int cpu)
 {
-	return local_softirq_pending();
-}
-
-static void run_ksoftirqd(unsigned int cpu)
-{
-	local_irq_disable();
-	if (local_softirq_pending()) {
-		/*
-		 * We can safely run softirq on inline stack, as we are not deep
-		 * in the task stack here.
-		 */
-		__do_softirq();
-		local_irq_enable();
-		cond_resched_rcu_qs();
-		return;
-	}
-	local_irq_enable();
+	return ksoftirqd_softirq_pending();
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
@@ -830,6 +1164,8 @@ static int takeover_tasklets(unsigned in
 
 static struct smp_hotplug_thread softirq_threads = {
 	.store			= &ksoftirqd,
+	.setup			= ksoftirqd_set_sched_params,
+	.cleanup		= ksoftirqd_clr_sched_params,
 	.thread_should_run	= ksoftirqd_should_run,
 	.thread_fn		= run_ksoftirqd,
 	.thread_comm		= "ksoftirqd/%u",
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -882,14 +882,7 @@ static bool can_stop_idle_tick(int cpu,
 		return false;
 
 	if (unlikely(local_softirq_pending() && cpu_online(cpu))) {
-		static int ratelimit;
-
-		if (ratelimit < 10 &&
-		    (local_softirq_pending() & SOFTIRQ_STOP_IDLE_MASK)) {
-			pr_warn("NOHZ: local_softirq_pending %02x\n",
-				(unsigned int) local_softirq_pending());
-			ratelimit++;
-		}
+		softirq_check_pending_idle();
 		return false;
 	}
 
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3856,11 +3856,9 @@ int netif_rx_ni(struct sk_buff *skb)
 
 	trace_netif_rx_ni_entry(skb);
 
-	preempt_disable();
+	local_bh_disable();
 	err = netif_rx_internal(skb);
-	if (local_softirq_pending())
-		do_softirq();
-	preempt_enable();
+	local_bh_enable();
 
 	return err;
 }