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kernel/softirq.c
19 KB
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/* * linux/kernel/softirq.c * * Copyright (C) 1992 Linus Torvalds * |
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* Distribute under GPLv2. * * Rewritten. Old one was good in 2.2, but in 2.3 it was immoral. --ANK (990903) |
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*/ |
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
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#include <linux/export.h> |
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#include <linux/kernel_stat.h> #include <linux/interrupt.h> #include <linux/init.h> #include <linux/mm.h> #include <linux/notifier.h> #include <linux/percpu.h> #include <linux/cpu.h> |
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#include <linux/freezer.h> |
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#include <linux/kthread.h> #include <linux/rcupdate.h> |
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#include <linux/ftrace.h> |
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#include <linux/smp.h> |
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#include <linux/smpboot.h> |
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#include <linux/tick.h> |
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#include <linux/irq.h> |
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#define CREATE_TRACE_POINTS |
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#include <trace/events/irq.h> |
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|
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/* - No shared variables, all the data are CPU local. - If a softirq needs serialization, let it serialize itself by its own spinlocks. - Even if softirq is serialized, only local cpu is marked for execution. Hence, we get something sort of weak cpu binding. Though it is still not clear, will it result in better locality or will not. Examples: - NET RX softirq. It is multithreaded and does not require any global serialization. - NET TX softirq. It kicks software netdevice queues, hence it is logically serialized per device, but this serialization is invisible to common code. - Tasklets: serialized wrt itself. */ #ifndef __ARCH_IRQ_STAT irq_cpustat_t irq_stat[NR_CPUS] ____cacheline_aligned; EXPORT_SYMBOL(irq_stat); #endif |
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static struct softirq_action softirq_vec[NR_SOFTIRQS] __cacheline_aligned_in_smp; |
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|
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DEFINE_PER_CPU(struct task_struct *, ksoftirqd); |
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|
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const char * const softirq_to_name[NR_SOFTIRQS] = { |
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"HI", "TIMER", "NET_TX", "NET_RX", "BLOCK", "IRQ_POLL", |
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"TASKLET", "SCHED", "HRTIMER", "RCU" |
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}; |
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/* * we cannot loop indefinitely here to avoid userspace starvation, * but we also don't want to introduce a worst case 1/HZ latency * to the pending events, so lets the scheduler to balance * the softirq load for us. */ |
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static void wakeup_softirqd(void) |
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{ /* Interrupts are disabled: no need to stop preemption */ |
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struct task_struct *tsk = __this_cpu_read(ksoftirqd); |
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if (tsk && tsk->state != TASK_RUNNING) wake_up_process(tsk); } /* |
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* If ksoftirqd is scheduled, we do not want to process pending softirqs |
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* right now. Let ksoftirqd handle this at its own rate, to get fairness, * unless we're doing some of the synchronous softirqs. |
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*/ |
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#define SOFTIRQ_NOW_MASK ((1 << HI_SOFTIRQ) | (1 << TASKLET_SOFTIRQ)) static bool ksoftirqd_running(unsigned long pending) |
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{ struct task_struct *tsk = __this_cpu_read(ksoftirqd); |
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if (pending & SOFTIRQ_NOW_MASK) return false; |
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return tsk && (tsk->state == TASK_RUNNING); } /* |
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* preempt_count and SOFTIRQ_OFFSET usage: * - preempt_count is changed by SOFTIRQ_OFFSET on entering or leaving * softirq processing. * - preempt_count is changed by SOFTIRQ_DISABLE_OFFSET (= 2 * SOFTIRQ_OFFSET) * on local_bh_disable or local_bh_enable. * This lets us distinguish between whether we are currently processing * softirq and whether we just have bh disabled. */ /* |
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* This one is for softirq.c-internal use, * where hardirqs are disabled legitimately: */ |
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#ifdef CONFIG_TRACE_IRQFLAGS |
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void __local_bh_disable_ip(unsigned long ip, unsigned int cnt) |
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{ unsigned long flags; WARN_ON_ONCE(in_irq()); raw_local_irq_save(flags); |
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/* |
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* The preempt tracer hooks into preempt_count_add and will break |
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* lockdep because it calls back into lockdep after SOFTIRQ_OFFSET * is set and before current->softirq_enabled is cleared. * We must manually increment preempt_count here and manually * call the trace_preempt_off later. */ |
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__preempt_count_add(cnt); |
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/* * Were softirqs turned off above: */ |
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if (softirq_count() == (cnt & SOFTIRQ_MASK)) |
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trace_softirqs_off(ip); raw_local_irq_restore(flags); |
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|
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if (preempt_count() == cnt) { #ifdef CONFIG_DEBUG_PREEMPT |
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current->preempt_disable_ip = get_lock_parent_ip(); |
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#endif |
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trace_preempt_off(CALLER_ADDR0, get_lock_parent_ip()); |
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} |
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} |
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EXPORT_SYMBOL(__local_bh_disable_ip); |
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#endif /* CONFIG_TRACE_IRQFLAGS */ |
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|
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static void __local_bh_enable(unsigned int cnt) { |
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WARN_ON_ONCE(!irqs_disabled()); |
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if (softirq_count() == (cnt & SOFTIRQ_MASK)) |
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trace_softirqs_on(_RET_IP_); |
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preempt_count_sub(cnt); |
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} |
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/* * Special-case - softirqs can safely be enabled in * cond_resched_softirq(), or by __do_softirq(), * without processing still-pending softirqs: */ void _local_bh_enable(void) { |
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WARN_ON_ONCE(in_irq()); |
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__local_bh_enable(SOFTIRQ_DISABLE_OFFSET); |
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} |
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EXPORT_SYMBOL(_local_bh_enable); |
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void __local_bh_enable_ip(unsigned long ip, unsigned int cnt) |
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{ |
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WARN_ON_ONCE(in_irq() || irqs_disabled()); |
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#ifdef CONFIG_TRACE_IRQFLAGS |
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local_irq_disable(); |
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#endif |
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/* * Are softirqs going to be turned on now: */ |
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if (softirq_count() == SOFTIRQ_DISABLE_OFFSET) |
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trace_softirqs_on(ip); |
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/* * Keep preemption disabled until we are done with * softirq processing: |
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*/ |
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preempt_count_sub(cnt - 1); |
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|
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if (unlikely(!in_interrupt() && local_softirq_pending())) { /* * Run softirq if any pending. And do it in its own stack * as we may be calling this deep in a task call stack already. */ |
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do_softirq(); |
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} |
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|
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preempt_count_dec(); |
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#ifdef CONFIG_TRACE_IRQFLAGS |
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local_irq_enable(); |
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#endif |
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preempt_check_resched(); } |
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EXPORT_SYMBOL(__local_bh_enable_ip); |
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/* |
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* We restart softirq processing for at most MAX_SOFTIRQ_RESTART times, * but break the loop if need_resched() is set or after 2 ms. * The MAX_SOFTIRQ_TIME provides a nice upper bound in most cases, but in * certain cases, such as stop_machine(), jiffies may cease to * increment and so we need the MAX_SOFTIRQ_RESTART limit as * well to make sure we eventually return from this method. |
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* |
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* These limits have been established via experimentation. |
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* The two things to balance is latency against fairness - * we want to handle softirqs as soon as possible, but they * should not be able to lock up the box. */ |
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#define MAX_SOFTIRQ_TIME msecs_to_jiffies(2) |
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#define MAX_SOFTIRQ_RESTART 10 |
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|
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#ifdef CONFIG_TRACE_IRQFLAGS /* |
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* When we run softirqs from irq_exit() and thus on the hardirq stack we need * to keep the lockdep irq context tracking as tight as possible in order to * not miss-qualify lock contexts and miss possible deadlocks. */ |
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|
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static inline bool lockdep_softirq_start(void) |
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{ |
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bool in_hardirq = false; |
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|
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if (trace_hardirq_context(current)) { in_hardirq = true; |
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trace_hardirq_exit(); |
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} |
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lockdep_softirq_enter(); |
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return in_hardirq; |
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} |
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static inline void lockdep_softirq_end(bool in_hardirq) |
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{ lockdep_softirq_exit(); |
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if (in_hardirq) |
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trace_hardirq_enter(); |
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} |
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#else |
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static inline bool lockdep_softirq_start(void) { return false; } static inline void lockdep_softirq_end(bool in_hardirq) { } |
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#endif |
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asmlinkage __visible void __softirq_entry __do_softirq(void) |
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{ |
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unsigned long end = jiffies + MAX_SOFTIRQ_TIME; |
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unsigned long old_flags = current->flags; |
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int max_restart = MAX_SOFTIRQ_RESTART; |
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struct softirq_action *h; |
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bool in_hardirq; |
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__u32 pending; |
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int softirq_bit; |
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/* * Mask out PF_MEMALLOC s current task context is borrowed for the * softirq. A softirq handled such as network RX might set PF_MEMALLOC * again if the socket is related to swap */ current->flags &= ~PF_MEMALLOC; |
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pending = local_softirq_pending(); |
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account_irq_enter_time(current); |
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|
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__local_bh_disable_ip(_RET_IP_, SOFTIRQ_OFFSET); |
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in_hardirq = lockdep_softirq_start(); |
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|
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restart: /* Reset the pending bitmask before enabling irqs */ |
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set_softirq_pending(0); |
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|
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local_irq_enable(); |
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h = softirq_vec; |
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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())) { |
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pr_err("huh, entered softirq %u %s %p with preempt_count %08x, exited with %08x? ", |
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vec_nr, softirq_to_name[vec_nr], h->action, prev_count, preempt_count()); preempt_count_set(prev_count); |
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} h++; |
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pending >>= softirq_bit; } |
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|
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rcu_bh_qs(); |
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local_irq_disable(); |
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pending = local_softirq_pending(); |
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if (pending) { |
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if (time_before(jiffies, end) && !need_resched() && --max_restart) |
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goto restart; |
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|
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wakeup_softirqd(); |
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} |
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|
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lockdep_softirq_end(in_hardirq); |
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account_irq_exit_time(current); |
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__local_bh_enable(SOFTIRQ_OFFSET); |
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WARN_ON_ONCE(in_interrupt()); |
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current_restore_flags(old_flags, PF_MEMALLOC); |
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} |
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asmlinkage __visible void do_softirq(void) |
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{ __u32 pending; unsigned long flags; if (in_interrupt()) return; local_irq_save(flags); pending = local_softirq_pending(); |
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if (pending && !ksoftirqd_running(pending)) |
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do_softirq_own_stack(); |
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local_irq_restore(flags); } |
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/* * Enter an interrupt context. */ void irq_enter(void) { |
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rcu_irq_enter(); |
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if (is_idle_task(current) && !in_interrupt()) { |
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/* * Prevent raise_softirq from needlessly waking up ksoftirqd * here, as softirq will be serviced on return from interrupt. */ local_bh_disable(); |
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tick_irq_enter(); |
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_local_bh_enable(); } __irq_enter(); |
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} |
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static inline void invoke_softirq(void) { |
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if (ksoftirqd_running(local_softirq_pending())) |
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return; |
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if (!force_irqthreads) { |
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#ifdef CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK |
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/* * We can safely execute softirq on the current stack if * it is the irq stack, because it should be near empty |
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* at this stage. */ __do_softirq(); #else /* * Otherwise, irq_exit() is called on the task stack that can * be potentially deep already. So call softirq in its own stack * to prevent from any overrun. |
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*/ |
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do_softirq_own_stack(); |
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#endif |
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} else { |
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wakeup_softirqd(); |
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} |
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} |
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|
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static inline void tick_irq_exit(void) { #ifdef CONFIG_NO_HZ_COMMON int cpu = smp_processor_id(); /* Make sure that timer wheel updates are propagated */ if ((idle_cpu(cpu) && !need_resched()) || tick_nohz_full_cpu(cpu)) { |
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if (!in_irq()) |
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tick_nohz_irq_exit(); } #endif } |
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/* * Exit an interrupt context. Process softirqs if needed and possible: */ void irq_exit(void) { |
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#ifndef __ARCH_IRQ_EXIT_IRQS_DISABLED |
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local_irq_disable(); |
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#else WARN_ON_ONCE(!irqs_disabled()); #endif |
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account_irq_exit_time(current); |
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preempt_count_sub(HARDIRQ_OFFSET); |
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if (!in_interrupt() && local_softirq_pending()) invoke_softirq(); |
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|
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tick_irq_exit(); |
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rcu_irq_exit(); |
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trace_hardirq_exit(); /* must be last! */ |
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} /* * This function must run with irqs disabled! */ |
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inline void raise_softirq_irqoff(unsigned int nr) |
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{ __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(); } |
7ad5b3a50 kernel: remove fa... |
417 |
void raise_softirq(unsigned int nr) |
1da177e4c Linux-2.6.12-rc2 |
418 419 420 421 422 423 424 |
{ unsigned long flags; local_irq_save(flags); raise_softirq_irqoff(nr); local_irq_restore(flags); } |
f069686e4 tracing/softirq: ... |
425 426 427 428 429 |
void __raise_softirq_irqoff(unsigned int nr) { trace_softirq_raise(nr); or_softirq_pending(1UL << nr); } |
962cf36c5 Remove argument f... |
430 |
void open_softirq(int nr, void (*action)(struct softirq_action *)) |
1da177e4c Linux-2.6.12-rc2 |
431 |
{ |
1da177e4c Linux-2.6.12-rc2 |
432 433 |
softirq_vec[nr].action = action; } |
9ba5f005c softirq: introduc... |
434 435 436 |
/* * Tasklets */ |
ce85b4f2e softirq: use cons... |
437 |
struct tasklet_head { |
48f20a9a9 tasklets: execute... |
438 439 |
struct tasklet_struct *head; struct tasklet_struct **tail; |
1da177e4c Linux-2.6.12-rc2 |
440 |
}; |
4620b49f7 softirq: remove i... |
441 442 |
static DEFINE_PER_CPU(struct tasklet_head, tasklet_vec); static DEFINE_PER_CPU(struct tasklet_head, tasklet_hi_vec); |
1da177e4c Linux-2.6.12-rc2 |
443 |
|
7ad5b3a50 kernel: remove fa... |
444 |
void __tasklet_schedule(struct tasklet_struct *t) |
1da177e4c Linux-2.6.12-rc2 |
445 446 447 448 |
{ unsigned long flags; local_irq_save(flags); |
48f20a9a9 tasklets: execute... |
449 |
t->next = NULL; |
909ea9646 core: Replace __g... |
450 451 |
*__this_cpu_read(tasklet_vec.tail) = t; __this_cpu_write(tasklet_vec.tail, &(t->next)); |
1da177e4c Linux-2.6.12-rc2 |
452 453 454 |
raise_softirq_irqoff(TASKLET_SOFTIRQ); local_irq_restore(flags); } |
1da177e4c Linux-2.6.12-rc2 |
455 |
EXPORT_SYMBOL(__tasklet_schedule); |
7ad5b3a50 kernel: remove fa... |
456 |
void __tasklet_hi_schedule(struct tasklet_struct *t) |
1da177e4c Linux-2.6.12-rc2 |
457 458 459 460 |
{ unsigned long flags; local_irq_save(flags); |
48f20a9a9 tasklets: execute... |
461 |
t->next = NULL; |
909ea9646 core: Replace __g... |
462 463 |
*__this_cpu_read(tasklet_hi_vec.tail) = t; __this_cpu_write(tasklet_hi_vec.tail, &(t->next)); |
1da177e4c Linux-2.6.12-rc2 |
464 465 466 |
raise_softirq_irqoff(HI_SOFTIRQ); local_irq_restore(flags); } |
1da177e4c Linux-2.6.12-rc2 |
467 |
EXPORT_SYMBOL(__tasklet_hi_schedule); |
0766f788e latent_entropy: M... |
468 |
static __latent_entropy void tasklet_action(struct softirq_action *a) |
1da177e4c Linux-2.6.12-rc2 |
469 470 471 472 |
{ struct tasklet_struct *list; local_irq_disable(); |
909ea9646 core: Replace __g... |
473 474 |
list = __this_cpu_read(tasklet_vec.head); __this_cpu_write(tasklet_vec.head, NULL); |
22127e93c time: Replace __g... |
475 |
__this_cpu_write(tasklet_vec.tail, this_cpu_ptr(&tasklet_vec.head)); |
1da177e4c Linux-2.6.12-rc2 |
476 477 478 479 480 481 482 483 484 |
local_irq_enable(); while (list) { struct tasklet_struct *t = list; list = list->next; if (tasklet_trylock(t)) { if (!atomic_read(&t->count)) { |
ce85b4f2e softirq: use cons... |
485 486 |
if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state)) |
1da177e4c Linux-2.6.12-rc2 |
487 488 489 490 491 492 493 494 495 |
BUG(); t->func(t->data); tasklet_unlock(t); continue; } tasklet_unlock(t); } local_irq_disable(); |
48f20a9a9 tasklets: execute... |
496 |
t->next = NULL; |
909ea9646 core: Replace __g... |
497 498 |
*__this_cpu_read(tasklet_vec.tail) = t; __this_cpu_write(tasklet_vec.tail, &(t->next)); |
1da177e4c Linux-2.6.12-rc2 |
499 500 501 502 |
__raise_softirq_irqoff(TASKLET_SOFTIRQ); local_irq_enable(); } } |
0766f788e latent_entropy: M... |
503 |
static __latent_entropy void tasklet_hi_action(struct softirq_action *a) |
1da177e4c Linux-2.6.12-rc2 |
504 505 506 507 |
{ struct tasklet_struct *list; local_irq_disable(); |
909ea9646 core: Replace __g... |
508 509 |
list = __this_cpu_read(tasklet_hi_vec.head); __this_cpu_write(tasklet_hi_vec.head, NULL); |
22127e93c time: Replace __g... |
510 |
__this_cpu_write(tasklet_hi_vec.tail, this_cpu_ptr(&tasklet_hi_vec.head)); |
1da177e4c Linux-2.6.12-rc2 |
511 512 513 514 515 516 517 518 519 |
local_irq_enable(); while (list) { struct tasklet_struct *t = list; list = list->next; if (tasklet_trylock(t)) { if (!atomic_read(&t->count)) { |
ce85b4f2e softirq: use cons... |
520 521 |
if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state)) |
1da177e4c Linux-2.6.12-rc2 |
522 523 524 525 526 527 528 529 530 |
BUG(); t->func(t->data); tasklet_unlock(t); continue; } tasklet_unlock(t); } local_irq_disable(); |
48f20a9a9 tasklets: execute... |
531 |
t->next = NULL; |
909ea9646 core: Replace __g... |
532 533 |
*__this_cpu_read(tasklet_hi_vec.tail) = t; __this_cpu_write(tasklet_hi_vec.tail, &(t->next)); |
1da177e4c Linux-2.6.12-rc2 |
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__raise_softirq_irqoff(HI_SOFTIRQ); local_irq_enable(); } } |
1da177e4c Linux-2.6.12-rc2 |
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void tasklet_init(struct tasklet_struct *t, void (*func)(unsigned long), unsigned long data) { t->next = NULL; t->state = 0; atomic_set(&t->count, 0); t->func = func; t->data = data; } |
1da177e4c Linux-2.6.12-rc2 |
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EXPORT_SYMBOL(tasklet_init); void tasklet_kill(struct tasklet_struct *t) { if (in_interrupt()) |
403227641 softirq: convert ... |
552 553 |
pr_notice("Attempt to kill tasklet from interrupt "); |
1da177e4c Linux-2.6.12-rc2 |
554 555 |
while (test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) { |
79d381c9f kernel/softirq.c:... |
556 |
do { |
1da177e4c Linux-2.6.12-rc2 |
557 |
yield(); |
79d381c9f kernel/softirq.c:... |
558 |
} while (test_bit(TASKLET_STATE_SCHED, &t->state)); |
1da177e4c Linux-2.6.12-rc2 |
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} tasklet_unlock_wait(t); clear_bit(TASKLET_STATE_SCHED, &t->state); } |
1da177e4c Linux-2.6.12-rc2 |
563 |
EXPORT_SYMBOL(tasklet_kill); |
9ba5f005c softirq: introduc... |
564 565 566 567 568 |
/* * tasklet_hrtimer */ /* |
b9c303227 hrtimer, softirq:... |
569 570 571 |
* The trampoline is called when the hrtimer expires. It schedules a tasklet * to run __tasklet_hrtimer_trampoline() which in turn will call the intended * hrtimer callback, but from softirq context. |
9ba5f005c softirq: introduc... |
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*/ static enum hrtimer_restart __hrtimer_tasklet_trampoline(struct hrtimer *timer) { struct tasklet_hrtimer *ttimer = container_of(timer, struct tasklet_hrtimer, timer); |
b9c303227 hrtimer, softirq:... |
577 578 |
tasklet_hi_schedule(&ttimer->tasklet); return HRTIMER_NORESTART; |
9ba5f005c softirq: introduc... |
579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 |
} /* * Helper function which calls the hrtimer callback from * tasklet/softirq context */ static void __tasklet_hrtimer_trampoline(unsigned long data) { struct tasklet_hrtimer *ttimer = (void *)data; enum hrtimer_restart restart; restart = ttimer->function(&ttimer->timer); if (restart != HRTIMER_NORESTART) hrtimer_restart(&ttimer->timer); } /** * tasklet_hrtimer_init - Init a tasklet/hrtimer combo for softirq callbacks * @ttimer: tasklet_hrtimer which is initialized |
25985edce Fix common misspe... |
598 |
* @function: hrtimer callback function which gets called from softirq context |
9ba5f005c softirq: introduc... |
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* @which_clock: clock id (CLOCK_MONOTONIC/CLOCK_REALTIME) * @mode: hrtimer mode (HRTIMER_MODE_ABS/HRTIMER_MODE_REL) */ void tasklet_hrtimer_init(struct tasklet_hrtimer *ttimer, enum hrtimer_restart (*function)(struct hrtimer *), clockid_t which_clock, enum hrtimer_mode mode) { hrtimer_init(&ttimer->timer, which_clock, mode); ttimer->timer.function = __hrtimer_tasklet_trampoline; tasklet_init(&ttimer->tasklet, __tasklet_hrtimer_trampoline, (unsigned long)ttimer); ttimer->function = function; } EXPORT_SYMBOL_GPL(tasklet_hrtimer_init); |
1da177e4c Linux-2.6.12-rc2 |
613 614 |
void __init softirq_init(void) { |
48f20a9a9 tasklets: execute... |
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int cpu; for_each_possible_cpu(cpu) { per_cpu(tasklet_vec, cpu).tail = &per_cpu(tasklet_vec, cpu).head; per_cpu(tasklet_hi_vec, cpu).tail = &per_cpu(tasklet_hi_vec, cpu).head; } |
962cf36c5 Remove argument f... |
623 624 |
open_softirq(TASKLET_SOFTIRQ, tasklet_action); open_softirq(HI_SOFTIRQ, tasklet_hi_action); |
1da177e4c Linux-2.6.12-rc2 |
625 |
} |
3e339b5da softirq: Use hotp... |
626 |
static int ksoftirqd_should_run(unsigned int cpu) |
1da177e4c Linux-2.6.12-rc2 |
627 |
{ |
3e339b5da softirq: Use hotp... |
628 629 |
return local_softirq_pending(); } |
1da177e4c Linux-2.6.12-rc2 |
630 |
|
3e339b5da softirq: Use hotp... |
631 632 633 634 |
static void run_ksoftirqd(unsigned int cpu) { local_irq_disable(); if (local_softirq_pending()) { |
0bed698a3 irq: Justify the ... |
635 636 637 638 |
/* * We can safely run softirq on inline stack, as we are not deep * in the task stack here. */ |
3e339b5da softirq: Use hotp... |
639 |
__do_softirq(); |
3e339b5da softirq: Use hotp... |
640 |
local_irq_enable(); |
60479676e ksoftirqd: Use ne... |
641 |
cond_resched_rcu_qs(); |
3e339b5da softirq: Use hotp... |
642 |
return; |
1da177e4c Linux-2.6.12-rc2 |
643 |
} |
3e339b5da softirq: Use hotp... |
644 |
local_irq_enable(); |
1da177e4c Linux-2.6.12-rc2 |
645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 |
} #ifdef CONFIG_HOTPLUG_CPU /* * tasklet_kill_immediate is called to remove a tasklet which can already be * scheduled for execution on @cpu. * * Unlike tasklet_kill, this function removes the tasklet * _immediately_, even if the tasklet is in TASKLET_STATE_SCHED state. * * When this function is called, @cpu must be in the CPU_DEAD state. */ void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu) { struct tasklet_struct **i; BUG_ON(cpu_online(cpu)); BUG_ON(test_bit(TASKLET_STATE_RUN, &t->state)); if (!test_bit(TASKLET_STATE_SCHED, &t->state)) return; /* CPU is dead, so no lock needed. */ |
48f20a9a9 tasklets: execute... |
668 |
for (i = &per_cpu(tasklet_vec, cpu).head; *i; i = &(*i)->next) { |
1da177e4c Linux-2.6.12-rc2 |
669 670 |
if (*i == t) { *i = t->next; |
48f20a9a9 tasklets: execute... |
671 672 673 |
/* If this was the tail element, move the tail ptr */ if (*i == NULL) per_cpu(tasklet_vec, cpu).tail = i; |
1da177e4c Linux-2.6.12-rc2 |
674 675 676 677 678 |
return; } } BUG(); } |
c4544dbc7 kernel/softirq: C... |
679 |
static int takeover_tasklets(unsigned int cpu) |
1da177e4c Linux-2.6.12-rc2 |
680 |
{ |
1da177e4c Linux-2.6.12-rc2 |
681 682 683 684 |
/* CPU is dead, so no lock needed. */ local_irq_disable(); /* Find end, append list for that CPU. */ |
e5e417232 Fix cpu hotplug p... |
685 |
if (&per_cpu(tasklet_vec, cpu).head != per_cpu(tasklet_vec, cpu).tail) { |
909ea9646 core: Replace __g... |
686 687 |
*__this_cpu_read(tasklet_vec.tail) = per_cpu(tasklet_vec, cpu).head; this_cpu_write(tasklet_vec.tail, per_cpu(tasklet_vec, cpu).tail); |
e5e417232 Fix cpu hotplug p... |
688 689 690 |
per_cpu(tasklet_vec, cpu).head = NULL; per_cpu(tasklet_vec, cpu).tail = &per_cpu(tasklet_vec, cpu).head; } |
1da177e4c Linux-2.6.12-rc2 |
691 |
raise_softirq_irqoff(TASKLET_SOFTIRQ); |
e5e417232 Fix cpu hotplug p... |
692 |
if (&per_cpu(tasklet_hi_vec, cpu).head != per_cpu(tasklet_hi_vec, cpu).tail) { |
909ea9646 core: Replace __g... |
693 694 |
*__this_cpu_read(tasklet_hi_vec.tail) = per_cpu(tasklet_hi_vec, cpu).head; __this_cpu_write(tasklet_hi_vec.tail, per_cpu(tasklet_hi_vec, cpu).tail); |
e5e417232 Fix cpu hotplug p... |
695 696 697 |
per_cpu(tasklet_hi_vec, cpu).head = NULL; per_cpu(tasklet_hi_vec, cpu).tail = &per_cpu(tasklet_hi_vec, cpu).head; } |
1da177e4c Linux-2.6.12-rc2 |
698 699 700 |
raise_softirq_irqoff(HI_SOFTIRQ); local_irq_enable(); |
c4544dbc7 kernel/softirq: C... |
701 |
return 0; |
1da177e4c Linux-2.6.12-rc2 |
702 |
} |
c4544dbc7 kernel/softirq: C... |
703 704 |
#else #define takeover_tasklets NULL |
1da177e4c Linux-2.6.12-rc2 |
705 |
#endif /* CONFIG_HOTPLUG_CPU */ |
3e339b5da softirq: Use hotp... |
706 707 708 709 710 711 |
static struct smp_hotplug_thread softirq_threads = { .store = &ksoftirqd, .thread_should_run = ksoftirqd_should_run, .thread_fn = run_ksoftirqd, .thread_comm = "ksoftirqd/%u", }; |
7babe8db9 Full conversion t... |
712 |
static __init int spawn_ksoftirqd(void) |
1da177e4c Linux-2.6.12-rc2 |
713 |
{ |
c4544dbc7 kernel/softirq: C... |
714 715 |
cpuhp_setup_state_nocalls(CPUHP_SOFTIRQ_DEAD, "softirq:dead", NULL, takeover_tasklets); |
3e339b5da softirq: Use hotp... |
716 |
BUG_ON(smpboot_register_percpu_thread(&softirq_threads)); |
1da177e4c Linux-2.6.12-rc2 |
717 718 |
return 0; } |
7babe8db9 Full conversion t... |
719 |
early_initcall(spawn_ksoftirqd); |
78eef01b0 [PATCH] on_each_c... |
720 |
|
43a256322 sparseirq: move _... |
721 722 723 724 725 726 727 728 729 |
/* * [ These __weak aliases are kept in a separate compilation unit, so that * GCC does not inline them incorrectly. ] */ int __init __weak early_irq_init(void) { return 0; } |
4a046d175 x86: arch_probe_n... |
730 731 |
int __init __weak arch_probe_nr_irqs(void) { |
b683de2b3 genirq: Query arc... |
732 |
return NR_IRQS_LEGACY; |
4a046d175 x86: arch_probe_n... |
733 |
} |
43a256322 sparseirq: move _... |
734 735 736 737 |
int __init __weak arch_early_irq_init(void) { return 0; } |
62a08ae2a genirq: x86: Ensu... |
738 739 740 741 742 |
unsigned int __weak arch_dynirq_lower_bound(unsigned int from) { return from; } |