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-rw-r--r--kernel/softirq.c187
1 files changed, 39 insertions, 148 deletions
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 53cc09ceb0b..11025ccc06d 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -6,8 +6,6 @@
* 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>
@@ -29,7 +27,6 @@
#define CREATE_TRACE_POINTS
#include <trace/events/irq.h>
-#include <asm/irq.h>
/*
- No shared variables, all the data are CPU local.
- If a softirq needs serialization, let it serialize itself
@@ -100,13 +97,13 @@ static void __local_bh_disable(unsigned long ip, unsigned int cnt)
raw_local_irq_save(flags);
/*
- * The preempt tracer hooks into add_preempt_count and will break
+ * The preempt tracer hooks into preempt_count_add 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() += cnt;
+ __preempt_count_add(cnt);
/*
* Were softirqs turned off above:
*/
@@ -120,7 +117,7 @@ static void __local_bh_disable(unsigned long ip, unsigned int cnt)
#else /* !CONFIG_TRACE_IRQFLAGS */
static inline void __local_bh_disable(unsigned long ip, unsigned int cnt)
{
- add_preempt_count(cnt);
+ preempt_count_add(cnt);
barrier();
}
#endif /* CONFIG_TRACE_IRQFLAGS */
@@ -134,12 +131,11 @@ EXPORT_SYMBOL(local_bh_disable);
static void __local_bh_enable(unsigned int cnt)
{
- WARN_ON_ONCE(in_irq());
WARN_ON_ONCE(!irqs_disabled());
if (softirq_count() == cnt)
trace_softirqs_on(_RET_IP_);
- sub_preempt_count(cnt);
+ preempt_count_sub(cnt);
}
/*
@@ -149,6 +145,7 @@ static void __local_bh_enable(unsigned int cnt)
*/
void _local_bh_enable(void)
{
+ WARN_ON_ONCE(in_irq());
__local_bh_enable(SOFTIRQ_DISABLE_OFFSET);
}
@@ -169,12 +166,17 @@ static inline void _local_bh_enable_ip(unsigned long ip)
* Keep preemption disabled until we are done with
* softirq processing:
*/
- sub_preempt_count(SOFTIRQ_DISABLE_OFFSET - 1);
+ preempt_count_sub(SOFTIRQ_DISABLE_OFFSET - 1);
- if (unlikely(!in_interrupt() && local_softirq_pending()))
+ 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.
+ */
do_softirq();
+ }
- dec_preempt_count();
+ preempt_count_dec();
#ifdef CONFIG_TRACE_IRQFLAGS
local_irq_enable();
#endif
@@ -256,7 +258,7 @@ restart:
" exited with %08x?\n", vec_nr,
softirq_to_name[vec_nr], h->action,
prev_count, preempt_count());
- preempt_count() = prev_count;
+ preempt_count_set(prev_count);
}
rcu_bh_qs(cpu);
@@ -280,10 +282,11 @@ restart:
account_irq_exit_time(current);
__local_bh_enable(SOFTIRQ_OFFSET);
+ WARN_ON_ONCE(in_interrupt());
tsk_restore_flags(current, old_flags, PF_MEMALLOC);
}
-#ifndef __ARCH_HAS_DO_SOFTIRQ
+
asmlinkage void do_softirq(void)
{
@@ -298,13 +301,11 @@ asmlinkage void do_softirq(void)
pending = local_softirq_pending();
if (pending)
- __do_softirq();
+ do_softirq_own_stack();
local_irq_restore(flags);
}
-#endif
-
/*
* Enter an interrupt context.
*/
@@ -328,10 +329,25 @@ void irq_enter(void)
static inline void invoke_softirq(void)
{
- if (!force_irqthreads)
+ if (!force_irqthreads) {
+#ifdef CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK
+ /*
+ * We can safely execute softirq on the current stack if
+ * it is the irq stack, because it should be near empty
+ * at this stage.
+ */
__do_softirq();
- else
+#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.
+ */
+ do_softirq_own_stack();
+#endif
+ } else {
wakeup_softirqd();
+ }
}
static inline void tick_irq_exit(void)
@@ -360,7 +376,7 @@ void irq_exit(void)
account_irq_exit_time(current);
trace_hardirq_exit();
- sub_preempt_count(HARDIRQ_OFFSET);
+ preempt_count_sub(HARDIRQ_OFFSET);
if (!in_interrupt() && local_softirq_pending())
invoke_softirq();
@@ -609,146 +625,17 @@ void tasklet_hrtimer_init(struct tasklet_hrtimer *ttimer,
}
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);
}
@@ -762,6 +649,10 @@ static void run_ksoftirqd(unsigned int cpu)
{
local_irq_disable();
if (local_softirq_pending()) {
+ /*
+ * We can safely run softirq on inline stack, as we are not deep
+ * in the task stack here.
+ */
__do_softirq();
rcu_note_context_switch(cpu);
local_irq_enable();
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2024-11-23 01:18:34 +0000