X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=kernel%2Fsoftirq.c;h=7c1a67ef027431e8f82d341ed7e729b9c0eec044;hb=eed63519e3e74d515d2007ecd895338d0ba2a85c;hp=c506f266a6b90ee9d887b9eeecdd45061e74ef1f;hpb=7babe8db99d305340cf4828ce1f5a1481d5622ef;p=safe%2Fjmp%2Flinux-2.6 diff --git a/kernel/softirq.c b/kernel/softirq.c index c506f26..7c1a67e 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -6,6 +6,8 @@ * Distribute under GPLv2. * * Rewritten. Old one was good in 2.2, but in 2.3 it was immoral. --ANK (990903) + * + * Remote softirq infrastructure is by Jens Axboe. */ #include @@ -19,9 +21,13 @@ #include #include #include +#include #include #include +#define CREATE_TRACE_POINTS +#include + #include /* - No shared variables, all the data are CPU local. @@ -46,17 +52,22 @@ irq_cpustat_t irq_stat[NR_CPUS] ____cacheline_aligned; EXPORT_SYMBOL(irq_stat); #endif -static struct softirq_action softirq_vec[32] __cacheline_aligned_in_smp; +static struct softirq_action softirq_vec[NR_SOFTIRQS] __cacheline_aligned_in_smp; static DEFINE_PER_CPU(struct task_struct *, ksoftirqd); +char *softirq_to_name[NR_SOFTIRQS] = { + "HI", "TIMER", "NET_TX", "NET_RX", "BLOCK", "BLOCK_IOPOLL", + "TASKLET", "SCHED", "HRTIMER", "RCU" +}; + /* * 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. */ -static inline void wakeup_softirqd(void) +void wakeup_softirqd(void) { /* Interrupts are disabled: no need to stop preemption */ struct task_struct *tsk = __get_cpu_var(ksoftirqd); @@ -77,13 +88,23 @@ static void __local_bh_disable(unsigned long ip) WARN_ON_ONCE(in_irq()); raw_local_irq_save(flags); - add_preempt_count(SOFTIRQ_OFFSET); + /* + * The preempt tracer hooks into add_preempt_count and will break + * 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. + */ + preempt_count() += SOFTIRQ_OFFSET; /* * Were softirqs turned off above: */ if (softirq_count() == SOFTIRQ_OFFSET) trace_softirqs_off(ip); raw_local_irq_restore(flags); + + if (preempt_count() == SOFTIRQ_OFFSET) + trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1)); } #else /* !CONFIG_TRACE_IRQFLAGS */ static inline void __local_bh_disable(unsigned long ip) @@ -100,20 +121,6 @@ void local_bh_disable(void) EXPORT_SYMBOL(local_bh_disable); -void __local_bh_enable(void) -{ - WARN_ON_ONCE(in_irq()); - - /* - * softirqs should never be enabled by __local_bh_enable(), - * it always nests inside local_bh_enable() sections: - */ - WARN_ON_ONCE(softirq_count() == SOFTIRQ_OFFSET); - - sub_preempt_count(SOFTIRQ_OFFSET); -} -EXPORT_SYMBOL_GPL(__local_bh_enable); - /* * Special-case - softirqs can safely be enabled in * cond_resched_softirq(), or by __do_softirq(), @@ -192,7 +199,7 @@ asmlinkage void __do_softirq(void) account_system_vtime(current); __local_bh_disable((unsigned long)__builtin_return_address(0)); - trace_softirq_enter(); + lockdep_softirq_enter(); cpu = smp_processor_id(); restart: @@ -205,8 +212,22 @@ restart: do { if (pending & 1) { + int prev_count = preempt_count(); + kstat_incr_softirqs_this_cpu(h - softirq_vec); + + trace_softirq_entry(h, softirq_vec); h->action(h); - rcu_bh_qsctr_inc(cpu); + trace_softirq_exit(h, softirq_vec); + if (unlikely(prev_count != preempt_count())) { + printk(KERN_ERR "huh, entered softirq %td %s %p" + "with preempt_count %08x," + " exited with %08x?\n", h - softirq_vec, + softirq_to_name[h - softirq_vec], + h->action, prev_count, preempt_count()); + preempt_count() = prev_count; + } + + rcu_bh_qs(cpu); } h++; pending >>= 1; @@ -221,7 +242,7 @@ restart: if (pending) wakeup_softirqd(); - trace_softirq_exit(); + lockdep_softirq_exit(); account_system_vtime(current); _local_bh_enable(); @@ -254,16 +275,14 @@ asmlinkage void do_softirq(void) */ void irq_enter(void) { -#ifdef CONFIG_NO_HZ int cpu = smp_processor_id(); - if (idle_cpu(cpu) && !in_interrupt()) - tick_nohz_stop_idle(cpu); -#endif - __irq_enter(); -#ifdef CONFIG_NO_HZ - if (idle_cpu(cpu)) - tick_nohz_update_jiffies(); -#endif + + rcu_irq_enter(); + if (idle_cpu(cpu) && !in_interrupt()) { + __irq_enter(); + tick_check_idle(cpu); + } else + __irq_enter(); } #ifdef __ARCH_IRQ_EXIT_IRQS_DISABLED @@ -283,11 +302,11 @@ void irq_exit(void) if (!in_interrupt() && local_softirq_pending()) invoke_softirq(); + rcu_irq_exit(); #ifdef CONFIG_NO_HZ /* Make sure that timer wheel updates are propagated */ - if (!in_interrupt() && idle_cpu(smp_processor_id()) && !need_resched()) + if (idle_cpu(smp_processor_id()) && !in_interrupt() && !need_resched()) tick_nohz_stop_sched_tick(0); - rcu_irq_exit(); #endif preempt_enable_no_resched(); } @@ -326,7 +345,9 @@ void open_softirq(int nr, void (*action)(struct softirq_action *)) softirq_vec[nr].action = action; } -/* Tasklets */ +/* + * Tasklets + */ struct tasklet_head { struct tasklet_struct *head; @@ -364,6 +385,17 @@ void __tasklet_hi_schedule(struct tasklet_struct *t) EXPORT_SYMBOL(__tasklet_hi_schedule); +void __tasklet_hi_schedule_first(struct tasklet_struct *t) +{ + BUG_ON(!irqs_disabled()); + + t->next = __get_cpu_var(tasklet_hi_vec).head; + __get_cpu_var(tasklet_hi_vec).head = t; + __raise_softirq_irqoff(HI_SOFTIRQ); +} + +EXPORT_SYMBOL(__tasklet_hi_schedule_first); + static void tasklet_action(struct softirq_action *a) { struct tasklet_struct *list; @@ -453,9 +485,9 @@ void tasklet_kill(struct tasklet_struct *t) printk("Attempt to kill tasklet from interrupt\n"); while (test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) { - do + do { yield(); - while (test_bit(TASKLET_STATE_SCHED, &t->state)); + } while (test_bit(TASKLET_STATE_SCHED, &t->state)); } tasklet_unlock_wait(t); clear_bit(TASKLET_STATE_SCHED, &t->state); @@ -463,22 +495,204 @@ void tasklet_kill(struct tasklet_struct *t) EXPORT_SYMBOL(tasklet_kill); +/* + * tasklet_hrtimer + */ + +/* + * 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. + */ +static enum hrtimer_restart __hrtimer_tasklet_trampoline(struct hrtimer *timer) +{ + struct tasklet_hrtimer *ttimer = + container_of(timer, struct tasklet_hrtimer, timer); + + tasklet_hi_schedule(&ttimer->tasklet); + return HRTIMER_NORESTART; +} + +/* + * 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 + * @function: hrtimer callback funtion which gets called from softirq context + * @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); + +/* + * Remote softirq bits + */ + +DEFINE_PER_CPU(struct list_head [NR_SOFTIRQS], softirq_work_list); +EXPORT_PER_CPU_SYMBOL(softirq_work_list); + +static void __local_trigger(struct call_single_data *cp, int softirq) +{ + struct list_head *head = &__get_cpu_var(softirq_work_list[softirq]); + + list_add_tail(&cp->list, head); + + /* Trigger the softirq only if the list was previously empty. */ + if (head->next == &cp->list) + raise_softirq_irqoff(softirq); +} + +#ifdef CONFIG_USE_GENERIC_SMP_HELPERS +static void remote_softirq_receive(void *data) +{ + struct call_single_data *cp = data; + unsigned long flags; + int softirq; + + softirq = cp->priv; + + local_irq_save(flags); + __local_trigger(cp, softirq); + local_irq_restore(flags); +} + +static int __try_remote_softirq(struct call_single_data *cp, int cpu, int softirq) +{ + if (cpu_online(cpu)) { + cp->func = remote_softirq_receive; + cp->info = cp; + cp->flags = 0; + cp->priv = softirq; + + __smp_call_function_single(cpu, cp, 0); + return 0; + } + return 1; +} +#else /* CONFIG_USE_GENERIC_SMP_HELPERS */ +static int __try_remote_softirq(struct call_single_data *cp, int cpu, int softirq) +{ + return 1; +} +#endif + +/** + * __send_remote_softirq - try to schedule softirq work on a remote cpu + * @cp: private SMP call function data area + * @cpu: the remote cpu + * @this_cpu: the currently executing cpu + * @softirq: the softirq for the work + * + * Attempt to schedule softirq work on a remote cpu. If this cannot be + * done, the work is instead queued up on the local cpu. + * + * Interrupts must be disabled. + */ +void __send_remote_softirq(struct call_single_data *cp, int cpu, int this_cpu, int softirq) +{ + if (cpu == this_cpu || __try_remote_softirq(cp, cpu, softirq)) + __local_trigger(cp, softirq); +} +EXPORT_SYMBOL(__send_remote_softirq); + +/** + * send_remote_softirq - try to schedule softirq work on a remote cpu + * @cp: private SMP call function data area + * @cpu: the remote cpu + * @softirq: the softirq for the work + * + * Like __send_remote_softirq except that disabling interrupts and + * computing the current cpu is done for the caller. + */ +void send_remote_softirq(struct call_single_data *cp, int cpu, int softirq) +{ + unsigned long flags; + int this_cpu; + + local_irq_save(flags); + this_cpu = smp_processor_id(); + __send_remote_softirq(cp, cpu, this_cpu, softirq); + local_irq_restore(flags); +} +EXPORT_SYMBOL(send_remote_softirq); + +static int __cpuinit remote_softirq_cpu_notify(struct notifier_block *self, + unsigned long action, void *hcpu) +{ + /* + * If a CPU goes away, splice its entries to the current CPU + * and trigger a run of the softirq + */ + if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) { + int cpu = (unsigned long) hcpu; + int i; + + local_irq_disable(); + for (i = 0; i < NR_SOFTIRQS; i++) { + struct list_head *head = &per_cpu(softirq_work_list[i], cpu); + struct list_head *local_head; + + if (list_empty(head)) + continue; + + local_head = &__get_cpu_var(softirq_work_list[i]); + list_splice_init(head, local_head); + raise_softirq_irqoff(i); + } + local_irq_enable(); + } + + return NOTIFY_OK; +} + +static struct notifier_block __cpuinitdata remote_softirq_cpu_notifier = { + .notifier_call = remote_softirq_cpu_notify, +}; + void __init softirq_init(void) { int cpu; for_each_possible_cpu(cpu) { + int i; + 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; + for (i = 0; i < NR_SOFTIRQS; i++) + INIT_LIST_HEAD(&per_cpu(softirq_work_list[i], cpu)); } + register_hotcpu_notifier(&remote_softirq_cpu_notifier); + open_softirq(TASKLET_SOFTIRQ, tasklet_action); open_softirq(HI_SOFTIRQ, tasklet_hi_action); } -static int ksoftirqd(void * __bind_cpu) +static int run_ksoftirqd(void * __bind_cpu) { set_current_state(TASK_INTERRUPTIBLE); @@ -502,6 +716,7 @@ static int ksoftirqd(void * __bind_cpu) preempt_enable_no_resched(); cond_resched(); preempt_disable(); + rcu_sched_qs((long)__bind_cpu); } preempt_enable(); set_current_state(TASK_INTERRUPTIBLE); @@ -590,7 +805,7 @@ static int __cpuinit cpu_callback(struct notifier_block *nfb, switch (action) { case CPU_UP_PREPARE: case CPU_UP_PREPARE_FROZEN: - p = kthread_create(ksoftirqd, hcpu, "ksoftirqd/%d", hotcpu); + p = kthread_create(run_ksoftirqd, hcpu, "ksoftirqd/%d", hotcpu); if (IS_ERR(p)) { printk("ksoftirqd for %i failed\n", hotcpu); return NOTIFY_BAD; @@ -609,7 +824,7 @@ static int __cpuinit cpu_callback(struct notifier_block *nfb, break; /* Unbind so it can run. Fall thru. */ kthread_bind(per_cpu(ksoftirqd, hotcpu), - any_online_cpu(cpu_online_map)); + cpumask_any(cpu_online_mask)); case CPU_DEAD: case CPU_DEAD_FROZEN: { struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 }; @@ -660,3 +875,28 @@ int on_each_cpu(void (*func) (void *info), void *info, int wait) } EXPORT_SYMBOL(on_each_cpu); #endif + +/* + * [ 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; +} + +int __init __weak arch_probe_nr_irqs(void) +{ + return 0; +} + +int __init __weak arch_early_irq_init(void) +{ + return 0; +} + +int __weak arch_init_chip_data(struct irq_desc *desc, int node) +{ + return 0; +}