* 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/export.h>
#define MAX_SOFTIRQ_TIME msecs_to_jiffies(2)
#define MAX_SOFTIRQ_RESTART 10
+ #ifdef CONFIG_TRACE_IRQFLAGS
+ /*
+ * Convoluted means of passing __do_softirq() a message through the various
+ * architecture execute_on_stack() bits.
+ *
+ * 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.
+ */
+ static DEFINE_PER_CPU(int, softirq_from_hardirq);
+
+ static inline void lockdep_softirq_from_hardirq(void)
+ {
+ this_cpu_write(softirq_from_hardirq, 1);
+ }
+
+ static inline void lockdep_softirq_start(void)
+ {
+ if (this_cpu_read(softirq_from_hardirq))
+ trace_hardirq_exit();
+ lockdep_softirq_enter();
+ }
+
+ static inline void lockdep_softirq_end(void)
+ {
+ lockdep_softirq_exit();
+ if (this_cpu_read(softirq_from_hardirq)) {
+ this_cpu_write(softirq_from_hardirq, 0);
+ trace_hardirq_enter();
+ }
+ }
+
+ #else
+ static inline void lockdep_softirq_from_hardirq(void) { }
+ static inline void lockdep_softirq_start(void) { }
+ static inline void lockdep_softirq_end(void) { }
+ #endif
+
asmlinkage void __do_softirq(void)
{
- struct softirq_action *h;
- __u32 pending;
unsigned long end = jiffies + MAX_SOFTIRQ_TIME;
- int cpu;
unsigned long old_flags = current->flags;
int max_restart = MAX_SOFTIRQ_RESTART;
+ struct softirq_action *h;
+ __u32 pending;
+ int cpu;
/*
* Mask out PF_MEMALLOC s current task context is borrowed for the
account_irq_enter_time(current);
__local_bh_disable(_RET_IP_, SOFTIRQ_OFFSET);
- lockdep_softirq_enter();
+ lockdep_softirq_start();
cpu = smp_processor_id();
restart:
wakeup_softirqd();
}
- lockdep_softirq_exit();
-
+ lockdep_softirq_end();
account_irq_exit_time(current);
__local_bh_enable(SOFTIRQ_OFFSET);
WARN_ON_ONCE(in_interrupt());
tsk_restore_flags(current, old_flags, PF_MEMALLOC);
}
-
-
asmlinkage void do_softirq(void)
{
__u32 pending;
static inline void invoke_softirq(void)
{
if (!force_irqthreads) {
+ lockdep_softirq_from_hardirq();
#ifdef CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK
/*
* We can safely execute softirq on the current stack if
#endif
account_irq_exit_time(current);
- trace_hardirq_exit();
preempt_count_sub(HARDIRQ_OFFSET);
if (!in_interrupt() && local_softirq_pending())
invoke_softirq();
tick_irq_exit();
rcu_irq_exit();
+ trace_hardirq_exit(); /* must be last! */
}
/*
}
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 = *(int *)cp->info;
- 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 = &softirq;
- cp->flags = 0;
-
- __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 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 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);
}
projects / ~andy / linux / commitdiff