* 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 <linux/module.h>
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);
EXPORT_SYMBOL(_local_bh_enable);
-void local_bh_enable(void)
+static inline void _local_bh_enable_ip(unsigned long ip)
{
+ WARN_ON_ONCE(in_irq() || irqs_disabled());
#ifdef CONFIG_TRACE_IRQFLAGS
- unsigned long flags;
-
- WARN_ON_ONCE(in_irq());
-#endif
- WARN_ON_ONCE(irqs_disabled());
-
-#ifdef CONFIG_TRACE_IRQFLAGS
- local_irq_save(flags);
+ local_irq_disable();
#endif
/*
* Are softirqs going to be turned on now:
*/
if (softirq_count() == SOFTIRQ_OFFSET)
- trace_softirqs_on((unsigned long)__builtin_return_address(0));
+ trace_softirqs_on(ip);
/*
* Keep preemption disabled until we are done with
* softirq processing:
dec_preempt_count();
#ifdef CONFIG_TRACE_IRQFLAGS
- local_irq_restore(flags);
+ local_irq_enable();
#endif
preempt_check_resched();
}
+
+void local_bh_enable(void)
+{
+ _local_bh_enable_ip((unsigned long)__builtin_return_address(0));
+}
EXPORT_SYMBOL(local_bh_enable);
void local_bh_enable_ip(unsigned long ip)
{
-#ifdef CONFIG_TRACE_IRQFLAGS
- unsigned long flags;
-
- WARN_ON_ONCE(in_irq());
-
- local_irq_save(flags);
-#endif
- /*
- * Are softirqs going to be turned on now:
- */
- if (softirq_count() == SOFTIRQ_OFFSET)
- trace_softirqs_on(ip);
- /*
- * Keep preemption disabled until we are done with
- * softirq processing:
- */
- sub_preempt_count(SOFTIRQ_OFFSET - 1);
-
- if (unlikely(!in_interrupt() && local_softirq_pending()))
- do_softirq();
-
- dec_preempt_count();
-#ifdef CONFIG_TRACE_IRQFLAGS
- local_irq_restore(flags);
-#endif
- preempt_check_resched();
+ _local_bh_enable_ip(ip);
}
EXPORT_SYMBOL(local_bh_enable_ip);
do {
if (pending & 1) {
+ int prev_count = preempt_count();
+
h->action(h);
+
+ if (unlikely(prev_count != preempt_count())) {
+ printk(KERN_ERR "huh, entered softirq %td %p"
+ "with preempt_count %08x,"
+ " exited with %08x?\n", h - softirq_vec,
+ h->action, prev_count, preempt_count());
+ preempt_count() = prev_count;
+ }
+
rcu_bh_qsctr_inc(cpu);
}
h++;
*/
void irq_enter(void)
{
- __irq_enter();
-#ifdef CONFIG_NO_HZ
- if (idle_cpu(smp_processor_id()))
- tick_nohz_update_jiffies();
-#endif
+ int cpu = smp_processor_id();
+
+ if (idle_cpu(cpu) && !in_interrupt()) {
+ __irq_enter();
+ tick_check_idle(cpu);
+ } else
+ __irq_enter();
}
#ifdef __ARCH_IRQ_EXIT_IRQS_DISABLED
#ifdef CONFIG_NO_HZ
/* Make sure that timer wheel updates are propagated */
if (!in_interrupt() && idle_cpu(smp_processor_id()) && !need_resched())
- tick_nohz_stop_sched_tick();
+ tick_nohz_stop_sched_tick(0);
+ rcu_irq_exit();
#endif
preempt_enable_no_resched();
}
/*
* This function must run with irqs disabled!
*/
-inline fastcall void raise_softirq_irqoff(unsigned int nr)
+inline void raise_softirq_irqoff(unsigned int nr)
{
__raise_softirq_irqoff(nr);
wakeup_softirqd();
}
-void fastcall raise_softirq(unsigned int nr)
+void raise_softirq(unsigned int nr)
{
unsigned long flags;
local_irq_restore(flags);
}
-void open_softirq(int nr, void (*action)(struct softirq_action*), void *data)
+void open_softirq(int nr, void (*action)(struct softirq_action *))
{
- softirq_vec[nr].data = data;
softirq_vec[nr].action = action;
}
/* Tasklets */
struct tasklet_head
{
- struct tasklet_struct *list;
+ struct tasklet_struct *head;
+ struct tasklet_struct **tail;
};
-/* Some compilers disobey section attribute on statics when not
- initialized -- RR */
-static DEFINE_PER_CPU(struct tasklet_head, tasklet_vec) = { NULL };
-static DEFINE_PER_CPU(struct tasklet_head, tasklet_hi_vec) = { NULL };
+static DEFINE_PER_CPU(struct tasklet_head, tasklet_vec);
+static DEFINE_PER_CPU(struct tasklet_head, tasklet_hi_vec);
-void fastcall __tasklet_schedule(struct tasklet_struct *t)
+void __tasklet_schedule(struct tasklet_struct *t)
{
unsigned long flags;
local_irq_save(flags);
- t->next = __get_cpu_var(tasklet_vec).list;
- __get_cpu_var(tasklet_vec).list = t;
+ t->next = NULL;
+ *__get_cpu_var(tasklet_vec).tail = t;
+ __get_cpu_var(tasklet_vec).tail = &(t->next);
raise_softirq_irqoff(TASKLET_SOFTIRQ);
local_irq_restore(flags);
}
EXPORT_SYMBOL(__tasklet_schedule);
-void fastcall __tasklet_hi_schedule(struct tasklet_struct *t)
+void __tasklet_hi_schedule(struct tasklet_struct *t)
{
unsigned long flags;
local_irq_save(flags);
- t->next = __get_cpu_var(tasklet_hi_vec).list;
- __get_cpu_var(tasklet_hi_vec).list = t;
+ t->next = NULL;
+ *__get_cpu_var(tasklet_hi_vec).tail = t;
+ __get_cpu_var(tasklet_hi_vec).tail = &(t->next);
raise_softirq_irqoff(HI_SOFTIRQ);
local_irq_restore(flags);
}
struct tasklet_struct *list;
local_irq_disable();
- list = __get_cpu_var(tasklet_vec).list;
- __get_cpu_var(tasklet_vec).list = NULL;
+ list = __get_cpu_var(tasklet_vec).head;
+ __get_cpu_var(tasklet_vec).head = NULL;
+ __get_cpu_var(tasklet_vec).tail = &__get_cpu_var(tasklet_vec).head;
local_irq_enable();
while (list) {
}
local_irq_disable();
- t->next = __get_cpu_var(tasklet_vec).list;
- __get_cpu_var(tasklet_vec).list = t;
+ t->next = NULL;
+ *__get_cpu_var(tasklet_vec).tail = t;
+ __get_cpu_var(tasklet_vec).tail = &(t->next);
__raise_softirq_irqoff(TASKLET_SOFTIRQ);
local_irq_enable();
}
struct tasklet_struct *list;
local_irq_disable();
- list = __get_cpu_var(tasklet_hi_vec).list;
- __get_cpu_var(tasklet_hi_vec).list = NULL;
+ list = __get_cpu_var(tasklet_hi_vec).head;
+ __get_cpu_var(tasklet_hi_vec).head = NULL;
+ __get_cpu_var(tasklet_hi_vec).tail = &__get_cpu_var(tasklet_hi_vec).head;
local_irq_enable();
while (list) {
}
local_irq_disable();
- t->next = __get_cpu_var(tasklet_hi_vec).list;
- __get_cpu_var(tasklet_hi_vec).list = t;
+ t->next = NULL;
+ *__get_cpu_var(tasklet_hi_vec).tail = t;
+ __get_cpu_var(tasklet_hi_vec).tail = &(t->next);
__raise_softirq_irqoff(HI_SOFTIRQ);
local_irq_enable();
}
EXPORT_SYMBOL(tasklet_kill);
+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);
+ 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)
{
- open_softirq(TASKLET_SOFTIRQ, tasklet_action, NULL);
- open_softirq(HI_SOFTIRQ, tasklet_hi_action, NULL);
+ 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)
return;
/* CPU is dead, so no lock needed. */
- for (i = &per_cpu(tasklet_vec, cpu).list; *i; i = &(*i)->next) {
+ for (i = &per_cpu(tasklet_vec, cpu).head; *i; i = &(*i)->next) {
if (*i == t) {
*i = t->next;
+ /* If this was the tail element, move the tail ptr */
+ if (*i == NULL)
+ per_cpu(tasklet_vec, cpu).tail = i;
return;
}
}
static void takeover_tasklets(unsigned int cpu)
{
- struct tasklet_struct **i;
-
/* CPU is dead, so no lock needed. */
local_irq_disable();
/* Find end, append list for that CPU. */
- for (i = &__get_cpu_var(tasklet_vec).list; *i; i = &(*i)->next);
- *i = per_cpu(tasklet_vec, cpu).list;
- per_cpu(tasklet_vec, cpu).list = NULL;
+ if (&per_cpu(tasklet_vec, cpu).head != per_cpu(tasklet_vec, cpu).tail) {
+ *(__get_cpu_var(tasklet_vec).tail) = per_cpu(tasklet_vec, cpu).head;
+ __get_cpu_var(tasklet_vec).tail = per_cpu(tasklet_vec, cpu).tail;
+ per_cpu(tasklet_vec, cpu).head = NULL;
+ per_cpu(tasklet_vec, cpu).tail = &per_cpu(tasklet_vec, cpu).head;
+ }
raise_softirq_irqoff(TASKLET_SOFTIRQ);
- for (i = &__get_cpu_var(tasklet_hi_vec).list; *i; i = &(*i)->next);
- *i = per_cpu(tasklet_hi_vec, cpu).list;
- per_cpu(tasklet_hi_vec, cpu).list = NULL;
+ if (&per_cpu(tasklet_hi_vec, cpu).head != per_cpu(tasklet_hi_vec, cpu).tail) {
+ *__get_cpu_var(tasklet_hi_vec).tail = per_cpu(tasklet_hi_vec, cpu).head;
+ __get_cpu_var(tasklet_hi_vec).tail = per_cpu(tasklet_hi_vec, cpu).tail;
+ per_cpu(tasklet_hi_vec, cpu).head = NULL;
+ per_cpu(tasklet_hi_vec, cpu).tail = &per_cpu(tasklet_hi_vec, cpu).head;
+ }
raise_softirq_irqoff(HI_SOFTIRQ);
local_irq_enable();
p = per_cpu(ksoftirqd, hotcpu);
per_cpu(ksoftirqd, hotcpu) = NULL;
- sched_setscheduler(p, SCHED_FIFO, ¶m);
+ sched_setscheduler_nocheck(p, SCHED_FIFO, ¶m);
kthread_stop(p);
takeover_tasklets(hotcpu);
break;
.notifier_call = cpu_callback
};
-__init int spawn_ksoftirqd(void)
+static __init int spawn_ksoftirqd(void)
{
void *cpu = (void *)(long)smp_processor_id();
int err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
register_cpu_notifier(&cpu_nfb);
return 0;
}
+early_initcall(spawn_ksoftirqd);
#ifdef CONFIG_SMP
/*
* Call a function on all processors
*/
-int on_each_cpu(void (*func) (void *info), void *info, int retry, int wait)
+int on_each_cpu(void (*func) (void *info), void *info, int wait)
{
int ret = 0;
preempt_disable();
- ret = smp_call_function(func, info, retry, wait);
+ ret = smp_call_function(func, info, wait);
local_irq_disable();
func(info);
local_irq_enable();