298 lines
6.8 KiB
C
298 lines
6.8 KiB
C
/*
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* trace context switch
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*
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* Copyright (C) 2007 Steven Rostedt <srostedt@redhat.com>
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*
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*/
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#include <linux/module.h>
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#include <linux/fs.h>
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#include <linux/debugfs.h>
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#include <linux/kallsyms.h>
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#include <linux/uaccess.h>
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#include <linux/ftrace.h>
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#include <trace/events/sched.h>
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#include "trace.h"
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static struct trace_array *ctx_trace;
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static int __read_mostly tracer_enabled;
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static int sched_ref;
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static DEFINE_MUTEX(sched_register_mutex);
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static int sched_stopped;
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void
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tracing_sched_switch_trace(struct trace_array *tr,
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struct task_struct *prev,
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struct task_struct *next,
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unsigned long flags, int pc)
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{
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struct ftrace_event_call *call = &event_context_switch;
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struct ring_buffer *buffer = tr->buffer;
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struct ring_buffer_event *event;
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struct ctx_switch_entry *entry;
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event = trace_buffer_lock_reserve(buffer, TRACE_CTX,
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sizeof(*entry), flags, pc);
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if (!event)
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return;
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entry = ring_buffer_event_data(event);
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entry->prev_pid = prev->pid;
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entry->prev_prio = prev->prio;
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entry->prev_state = prev->state;
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entry->next_pid = next->pid;
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entry->next_prio = next->prio;
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entry->next_state = next->state;
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entry->next_cpu = task_cpu(next);
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if (!filter_check_discard(call, entry, buffer, event))
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trace_buffer_unlock_commit(buffer, event, flags, pc);
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}
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static void
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probe_sched_switch(void *ignore, struct task_struct *prev, struct task_struct *next)
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{
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struct trace_array_cpu *data;
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unsigned long flags;
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int cpu;
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int pc;
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if (unlikely(!sched_ref))
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return;
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tracing_record_cmdline(prev);
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tracing_record_cmdline(next);
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if (!tracer_enabled || sched_stopped)
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return;
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pc = preempt_count();
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local_irq_save(flags);
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cpu = raw_smp_processor_id();
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data = ctx_trace->data[cpu];
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if (likely(!atomic_read(&data->disabled)))
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tracing_sched_switch_trace(ctx_trace, prev, next, flags, pc);
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local_irq_restore(flags);
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}
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void
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tracing_sched_wakeup_trace(struct trace_array *tr,
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struct task_struct *wakee,
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struct task_struct *curr,
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unsigned long flags, int pc)
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{
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struct ftrace_event_call *call = &event_wakeup;
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struct ring_buffer_event *event;
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struct ctx_switch_entry *entry;
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struct ring_buffer *buffer = tr->buffer;
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event = trace_buffer_lock_reserve(buffer, TRACE_WAKE,
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sizeof(*entry), flags, pc);
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if (!event)
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return;
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entry = ring_buffer_event_data(event);
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entry->prev_pid = curr->pid;
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entry->prev_prio = curr->prio;
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entry->prev_state = curr->state;
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entry->next_pid = wakee->pid;
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entry->next_prio = wakee->prio;
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entry->next_state = wakee->state;
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entry->next_cpu = task_cpu(wakee);
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if (!filter_check_discard(call, entry, buffer, event))
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ring_buffer_unlock_commit(buffer, event);
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ftrace_trace_stack(tr->buffer, flags, 6, pc);
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ftrace_trace_userstack(tr->buffer, flags, pc);
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}
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static void
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probe_sched_wakeup(void *ignore, struct task_struct *wakee, int success)
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{
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struct trace_array_cpu *data;
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unsigned long flags;
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int cpu, pc;
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if (unlikely(!sched_ref))
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return;
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tracing_record_cmdline(current);
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if (!tracer_enabled || sched_stopped)
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return;
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pc = preempt_count();
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local_irq_save(flags);
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cpu = raw_smp_processor_id();
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data = ctx_trace->data[cpu];
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if (likely(!atomic_read(&data->disabled)))
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tracing_sched_wakeup_trace(ctx_trace, wakee, current,
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flags, pc);
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local_irq_restore(flags);
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}
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static int tracing_sched_register(void)
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{
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int ret;
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ret = register_trace_sched_wakeup(probe_sched_wakeup, NULL);
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if (ret) {
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pr_info("wakeup trace: Couldn't activate tracepoint"
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" probe to kernel_sched_wakeup\n");
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return ret;
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}
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ret = register_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
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if (ret) {
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pr_info("wakeup trace: Couldn't activate tracepoint"
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" probe to kernel_sched_wakeup_new\n");
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goto fail_deprobe;
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}
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ret = register_trace_sched_switch(probe_sched_switch, NULL);
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if (ret) {
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pr_info("sched trace: Couldn't activate tracepoint"
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" probe to kernel_sched_switch\n");
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goto fail_deprobe_wake_new;
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}
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return ret;
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fail_deprobe_wake_new:
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unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
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fail_deprobe:
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unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
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return ret;
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}
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static void tracing_sched_unregister(void)
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{
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unregister_trace_sched_switch(probe_sched_switch, NULL);
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unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
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unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
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}
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static void tracing_start_sched_switch(void)
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{
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mutex_lock(&sched_register_mutex);
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if (!(sched_ref++))
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tracing_sched_register();
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mutex_unlock(&sched_register_mutex);
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}
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static void tracing_stop_sched_switch(void)
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{
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mutex_lock(&sched_register_mutex);
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if (!(--sched_ref))
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tracing_sched_unregister();
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mutex_unlock(&sched_register_mutex);
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}
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void tracing_start_cmdline_record(void)
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{
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tracing_start_sched_switch();
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}
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void tracing_stop_cmdline_record(void)
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{
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tracing_stop_sched_switch();
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}
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/**
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* tracing_start_sched_switch_record - start tracing context switches
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*
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* Turns on context switch tracing for a tracer.
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*/
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void tracing_start_sched_switch_record(void)
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{
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if (unlikely(!ctx_trace)) {
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WARN_ON(1);
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return;
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}
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tracing_start_sched_switch();
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mutex_lock(&sched_register_mutex);
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tracer_enabled++;
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mutex_unlock(&sched_register_mutex);
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}
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/**
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* tracing_stop_sched_switch_record - start tracing context switches
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*
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* Turns off context switch tracing for a tracer.
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*/
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void tracing_stop_sched_switch_record(void)
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{
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mutex_lock(&sched_register_mutex);
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tracer_enabled--;
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WARN_ON(tracer_enabled < 0);
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mutex_unlock(&sched_register_mutex);
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tracing_stop_sched_switch();
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}
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/**
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* tracing_sched_switch_assign_trace - assign a trace array for ctx switch
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* @tr: trace array pointer to assign
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*
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* Some tracers might want to record the context switches in their
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* trace. This function lets those tracers assign the trace array
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* to use.
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*/
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void tracing_sched_switch_assign_trace(struct trace_array *tr)
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{
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ctx_trace = tr;
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}
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static void stop_sched_trace(struct trace_array *tr)
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{
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tracing_stop_sched_switch_record();
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}
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static int sched_switch_trace_init(struct trace_array *tr)
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{
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ctx_trace = tr;
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tracing_reset_online_cpus(tr);
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tracing_start_sched_switch_record();
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return 0;
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}
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static void sched_switch_trace_reset(struct trace_array *tr)
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{
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if (sched_ref)
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stop_sched_trace(tr);
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}
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static void sched_switch_trace_start(struct trace_array *tr)
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{
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sched_stopped = 0;
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}
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static void sched_switch_trace_stop(struct trace_array *tr)
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{
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sched_stopped = 1;
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}
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static struct tracer sched_switch_trace __read_mostly =
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{
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.name = "sched_switch",
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.init = sched_switch_trace_init,
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.reset = sched_switch_trace_reset,
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.start = sched_switch_trace_start,
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.stop = sched_switch_trace_stop,
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.wait_pipe = poll_wait_pipe,
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#ifdef CONFIG_FTRACE_SELFTEST
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.selftest = trace_selftest_startup_sched_switch,
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#endif
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};
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__init static int init_sched_switch_trace(void)
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{
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return register_tracer(&sched_switch_trace);
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}
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device_initcall(init_sched_switch_trace);
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