| /* |
| * trace task wakeup timings |
| * |
| * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com> |
| * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com> |
| * |
| * Based on code from the latency_tracer, that is: |
| * |
| * Copyright (C) 2004-2006 Ingo Molnar |
| * Copyright (C) 2004 William Lee Irwin III |
| */ |
| #include <linux/module.h> |
| #include <linux/fs.h> |
| #include <linux/debugfs.h> |
| #include <linux/kallsyms.h> |
| #include <linux/uaccess.h> |
| #include <linux/ftrace.h> |
| #include <linux/marker.h> |
| |
| #include "trace.h" |
| |
| static struct trace_array *wakeup_trace; |
| static int __read_mostly tracer_enabled; |
| |
| static struct task_struct *wakeup_task; |
| static int wakeup_cpu; |
| static unsigned wakeup_prio = -1; |
| |
| static DEFINE_SPINLOCK(wakeup_lock); |
| |
| static void __wakeup_reset(struct trace_array *tr); |
| |
| #ifdef CONFIG_FTRACE |
| /* |
| * irqsoff uses its own tracer function to keep the overhead down: |
| */ |
| static void |
| wakeup_tracer_call(unsigned long ip, unsigned long parent_ip) |
| { |
| struct trace_array *tr = wakeup_trace; |
| struct trace_array_cpu *data; |
| unsigned long flags; |
| long disabled; |
| int resched; |
| int cpu; |
| |
| if (likely(!wakeup_task)) |
| return; |
| |
| resched = need_resched(); |
| preempt_disable_notrace(); |
| |
| cpu = raw_smp_processor_id(); |
| data = tr->data[cpu]; |
| disabled = atomic_inc_return(&data->disabled); |
| if (unlikely(disabled != 1)) |
| goto out; |
| |
| spin_lock_irqsave(&wakeup_lock, flags); |
| |
| if (unlikely(!wakeup_task)) |
| goto unlock; |
| |
| /* |
| * The task can't disappear because it needs to |
| * wake up first, and we have the wakeup_lock. |
| */ |
| if (task_cpu(wakeup_task) != cpu) |
| goto unlock; |
| |
| trace_function(tr, data, ip, parent_ip, flags); |
| |
| unlock: |
| spin_unlock_irqrestore(&wakeup_lock, flags); |
| |
| out: |
| atomic_dec(&data->disabled); |
| |
| /* |
| * To prevent recursion from the scheduler, if the |
| * resched flag was set before we entered, then |
| * don't reschedule. |
| */ |
| if (resched) |
| preempt_enable_no_resched_notrace(); |
| else |
| preempt_enable_notrace(); |
| } |
| |
| static struct ftrace_ops trace_ops __read_mostly = |
| { |
| .func = wakeup_tracer_call, |
| }; |
| #endif /* CONFIG_FTRACE */ |
| |
| /* |
| * Should this new latency be reported/recorded? |
| */ |
| static int report_latency(cycle_t delta) |
| { |
| if (tracing_thresh) { |
| if (delta < tracing_thresh) |
| return 0; |
| } else { |
| if (delta <= tracing_max_latency) |
| return 0; |
| } |
| return 1; |
| } |
| |
| static void notrace |
| wakeup_sched_switch(void *private, void *rq, struct task_struct *prev, |
| struct task_struct *next) |
| { |
| unsigned long latency = 0, t0 = 0, t1 = 0; |
| struct trace_array **ptr = private; |
| struct trace_array *tr = *ptr; |
| struct trace_array_cpu *data; |
| cycle_t T0, T1, delta; |
| unsigned long flags; |
| long disabled; |
| int cpu; |
| |
| if (unlikely(!tracer_enabled)) |
| return; |
| |
| /* |
| * When we start a new trace, we set wakeup_task to NULL |
| * and then set tracer_enabled = 1. We want to make sure |
| * that another CPU does not see the tracer_enabled = 1 |
| * and the wakeup_task with an older task, that might |
| * actually be the same as next. |
| */ |
| smp_rmb(); |
| |
| if (next != wakeup_task) |
| return; |
| |
| /* The task we are waiting for is waking up */ |
| data = tr->data[wakeup_cpu]; |
| |
| /* disable local data, not wakeup_cpu data */ |
| cpu = raw_smp_processor_id(); |
| disabled = atomic_inc_return(&tr->data[cpu]->disabled); |
| if (likely(disabled != 1)) |
| goto out; |
| |
| spin_lock_irqsave(&wakeup_lock, flags); |
| |
| /* We could race with grabbing wakeup_lock */ |
| if (unlikely(!tracer_enabled || next != wakeup_task)) |
| goto out_unlock; |
| |
| trace_function(tr, data, CALLER_ADDR1, CALLER_ADDR2, flags); |
| |
| /* |
| * usecs conversion is slow so we try to delay the conversion |
| * as long as possible: |
| */ |
| T0 = data->preempt_timestamp; |
| T1 = ftrace_now(cpu); |
| delta = T1-T0; |
| |
| if (!report_latency(delta)) |
| goto out_unlock; |
| |
| latency = nsecs_to_usecs(delta); |
| |
| tracing_max_latency = delta; |
| t0 = nsecs_to_usecs(T0); |
| t1 = nsecs_to_usecs(T1); |
| |
| update_max_tr(tr, wakeup_task, wakeup_cpu); |
| |
| out_unlock: |
| __wakeup_reset(tr); |
| spin_unlock_irqrestore(&wakeup_lock, flags); |
| out: |
| atomic_dec(&tr->data[cpu]->disabled); |
| } |
| |
| static notrace void |
| sched_switch_callback(void *probe_data, void *call_data, |
| const char *format, va_list *args) |
| { |
| struct task_struct *prev; |
| struct task_struct *next; |
| struct rq *__rq; |
| |
| /* skip prev_pid %d next_pid %d prev_state %ld */ |
| (void)va_arg(*args, int); |
| (void)va_arg(*args, int); |
| (void)va_arg(*args, long); |
| __rq = va_arg(*args, typeof(__rq)); |
| prev = va_arg(*args, typeof(prev)); |
| next = va_arg(*args, typeof(next)); |
| |
| tracing_record_cmdline(prev); |
| |
| /* |
| * If tracer_switch_func only points to the local |
| * switch func, it still needs the ptr passed to it. |
| */ |
| wakeup_sched_switch(probe_data, __rq, prev, next); |
| } |
| |
| static void __wakeup_reset(struct trace_array *tr) |
| { |
| struct trace_array_cpu *data; |
| int cpu; |
| |
| assert_spin_locked(&wakeup_lock); |
| |
| for_each_possible_cpu(cpu) { |
| data = tr->data[cpu]; |
| tracing_reset(data); |
| } |
| |
| wakeup_cpu = -1; |
| wakeup_prio = -1; |
| |
| if (wakeup_task) |
| put_task_struct(wakeup_task); |
| |
| wakeup_task = NULL; |
| } |
| |
| static void wakeup_reset(struct trace_array *tr) |
| { |
| unsigned long flags; |
| |
| spin_lock_irqsave(&wakeup_lock, flags); |
| __wakeup_reset(tr); |
| spin_unlock_irqrestore(&wakeup_lock, flags); |
| } |
| |
| static void |
| wakeup_check_start(struct trace_array *tr, struct task_struct *p, |
| struct task_struct *curr) |
| { |
| int cpu = smp_processor_id(); |
| unsigned long flags; |
| long disabled; |
| |
| if (likely(!rt_task(p)) || |
| p->prio >= wakeup_prio || |
| p->prio >= curr->prio) |
| return; |
| |
| disabled = atomic_inc_return(&tr->data[cpu]->disabled); |
| if (unlikely(disabled != 1)) |
| goto out; |
| |
| /* interrupts should be off from try_to_wake_up */ |
| spin_lock(&wakeup_lock); |
| |
| /* check for races. */ |
| if (!tracer_enabled || p->prio >= wakeup_prio) |
| goto out_locked; |
| |
| /* reset the trace */ |
| __wakeup_reset(tr); |
| |
| wakeup_cpu = task_cpu(p); |
| wakeup_prio = p->prio; |
| |
| wakeup_task = p; |
| get_task_struct(wakeup_task); |
| |
| local_save_flags(flags); |
| |
| tr->data[wakeup_cpu]->preempt_timestamp = ftrace_now(cpu); |
| trace_function(tr, tr->data[wakeup_cpu], |
| CALLER_ADDR1, CALLER_ADDR2, flags); |
| |
| out_locked: |
| spin_unlock(&wakeup_lock); |
| out: |
| atomic_dec(&tr->data[cpu]->disabled); |
| } |
| |
| static notrace void |
| wake_up_callback(void *probe_data, void *call_data, |
| const char *format, va_list *args) |
| { |
| struct trace_array **ptr = probe_data; |
| struct trace_array *tr = *ptr; |
| struct task_struct *curr; |
| struct task_struct *task; |
| struct rq *__rq; |
| |
| if (likely(!tracer_enabled)) |
| return; |
| |
| /* Skip pid %d state %ld */ |
| (void)va_arg(*args, int); |
| (void)va_arg(*args, long); |
| /* now get the meat: "rq %p task %p rq->curr %p" */ |
| __rq = va_arg(*args, typeof(__rq)); |
| task = va_arg(*args, typeof(task)); |
| curr = va_arg(*args, typeof(curr)); |
| |
| tracing_record_cmdline(task); |
| tracing_record_cmdline(curr); |
| |
| wakeup_check_start(tr, task, curr); |
| } |
| |
| static void start_wakeup_tracer(struct trace_array *tr) |
| { |
| int ret; |
| |
| ret = marker_probe_register("kernel_sched_wakeup", |
| "pid %d state %ld ## rq %p task %p rq->curr %p", |
| wake_up_callback, |
| &wakeup_trace); |
| if (ret) { |
| pr_info("wakeup trace: Couldn't add marker" |
| " probe to kernel_sched_wakeup\n"); |
| return; |
| } |
| |
| ret = marker_probe_register("kernel_sched_wakeup_new", |
| "pid %d state %ld ## rq %p task %p rq->curr %p", |
| wake_up_callback, |
| &wakeup_trace); |
| if (ret) { |
| pr_info("wakeup trace: Couldn't add marker" |
| " probe to kernel_sched_wakeup_new\n"); |
| goto fail_deprobe; |
| } |
| |
| ret = marker_probe_register("kernel_sched_schedule", |
| "prev_pid %d next_pid %d prev_state %ld " |
| "## rq %p prev %p next %p", |
| sched_switch_callback, |
| &wakeup_trace); |
| if (ret) { |
| pr_info("sched trace: Couldn't add marker" |
| " probe to kernel_sched_schedule\n"); |
| goto fail_deprobe_wake_new; |
| } |
| |
| wakeup_reset(tr); |
| |
| /* |
| * Don't let the tracer_enabled = 1 show up before |
| * the wakeup_task is reset. This may be overkill since |
| * wakeup_reset does a spin_unlock after setting the |
| * wakeup_task to NULL, but I want to be safe. |
| * This is a slow path anyway. |
| */ |
| smp_wmb(); |
| |
| tracer_enabled = 1; |
| register_ftrace_function(&trace_ops); |
| |
| return; |
| fail_deprobe_wake_new: |
| marker_probe_unregister("kernel_sched_wakeup_new", |
| wake_up_callback, |
| &wakeup_trace); |
| fail_deprobe: |
| marker_probe_unregister("kernel_sched_wakeup", |
| wake_up_callback, |
| &wakeup_trace); |
| } |
| |
| static void stop_wakeup_tracer(struct trace_array *tr) |
| { |
| tracer_enabled = 0; |
| unregister_ftrace_function(&trace_ops); |
| marker_probe_unregister("kernel_sched_schedule", |
| sched_switch_callback, |
| &wakeup_trace); |
| marker_probe_unregister("kernel_sched_wakeup_new", |
| wake_up_callback, |
| &wakeup_trace); |
| marker_probe_unregister("kernel_sched_wakeup", |
| wake_up_callback, |
| &wakeup_trace); |
| } |
| |
| static void wakeup_tracer_init(struct trace_array *tr) |
| { |
| wakeup_trace = tr; |
| |
| if (tr->ctrl) |
| start_wakeup_tracer(tr); |
| } |
| |
| static void wakeup_tracer_reset(struct trace_array *tr) |
| { |
| if (tr->ctrl) { |
| stop_wakeup_tracer(tr); |
| /* make sure we put back any tasks we are tracing */ |
| wakeup_reset(tr); |
| } |
| } |
| |
| static void wakeup_tracer_ctrl_update(struct trace_array *tr) |
| { |
| if (tr->ctrl) |
| start_wakeup_tracer(tr); |
| else |
| stop_wakeup_tracer(tr); |
| } |
| |
| static void wakeup_tracer_open(struct trace_iterator *iter) |
| { |
| /* stop the trace while dumping */ |
| if (iter->tr->ctrl) |
| stop_wakeup_tracer(iter->tr); |
| } |
| |
| static void wakeup_tracer_close(struct trace_iterator *iter) |
| { |
| /* forget about any processes we were recording */ |
| if (iter->tr->ctrl) |
| start_wakeup_tracer(iter->tr); |
| } |
| |
| static struct tracer wakeup_tracer __read_mostly = |
| { |
| .name = "wakeup", |
| .init = wakeup_tracer_init, |
| .reset = wakeup_tracer_reset, |
| .open = wakeup_tracer_open, |
| .close = wakeup_tracer_close, |
| .ctrl_update = wakeup_tracer_ctrl_update, |
| .print_max = 1, |
| #ifdef CONFIG_FTRACE_SELFTEST |
| .selftest = trace_selftest_startup_wakeup, |
| #endif |
| }; |
| |
| __init static int init_wakeup_tracer(void) |
| { |
| int ret; |
| |
| ret = register_tracer(&wakeup_tracer); |
| if (ret) |
| return ret; |
| |
| return 0; |
| } |
| device_initcall(init_wakeup_tracer); |