diff options
| -rw-r--r-- | include/linux/interrupt.h | 21 | ||||
| -rw-r--r-- | include/linux/smp.h | 4 | ||||
| -rw-r--r-- | kernel/softirq.c | 129 |
3 files changed, 153 insertions, 1 deletions
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h index 54b3623434e..35a61dc60d5 100644 --- a/include/linux/interrupt.h +++ b/include/linux/interrupt.h @@ -11,6 +11,8 @@ #include <linux/hardirq.h> #include <linux/sched.h> #include <linux/irqflags.h> +#include <linux/smp.h> +#include <linux/percpu.h> #include <asm/atomic.h> #include <asm/ptrace.h> #include <asm/system.h> @@ -273,6 +275,25 @@ extern void softirq_init(void); extern void raise_softirq_irqoff(unsigned int nr); extern void raise_softirq(unsigned int nr); +/* This is the worklist that queues up per-cpu softirq work. + * + * send_remote_sendirq() adds work to these lists, and + * the softirq handler itself dequeues from them. The queues + * are protected by disabling local cpu interrupts and they must + * only be accessed by the local cpu that they are for. + */ +DECLARE_PER_CPU(struct list_head [NR_SOFTIRQS], softirq_work_list); + +/* Try to send a softirq to a remote cpu. If this cannot be done, the + * work will be queued to the local cpu. + */ +extern void send_remote_softirq(struct call_single_data *cp, int cpu, int softirq); + +/* Like send_remote_softirq(), but the caller must disable local cpu interrupts + * and compute the current cpu, passed in as 'this_cpu'. + */ +extern void __send_remote_softirq(struct call_single_data *cp, int cpu, + int this_cpu, int softirq); /* Tasklets --- multithreaded analogue of BHs. diff --git a/include/linux/smp.h b/include/linux/smp.h index 66484d4a845..2e4d58b26c0 100644 --- a/include/linux/smp.h +++ b/include/linux/smp.h @@ -7,6 +7,7 @@ */ #include <linux/errno.h> +#include <linux/types.h> #include <linux/list.h> #include <linux/cpumask.h> @@ -16,7 +17,8 @@ struct call_single_data { struct list_head list; void (*func) (void *info); void *info; - unsigned int flags; + u16 flags; + u16 priv; }; #ifdef CONFIG_SMP diff --git a/kernel/softirq.c b/kernel/softirq.c index 37d67aa2d56..83ba21a13bd 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 <linux/module.h> @@ -474,17 +476,144 @@ void tasklet_kill(struct tasklet_struct *t) 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) { 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); } |