| /* |
| * 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 <trace/sched.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 int wakeup_rt; |
| |
| static raw_spinlock_t wakeup_lock = |
| (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED; |
| |
| static void __wakeup_reset(struct trace_array *tr); |
| |
| #ifdef CONFIG_FUNCTION_TRACER |
| /* |
| * 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; |
| int pc; |
| |
| if (likely(!wakeup_task)) |
| return; |
| |
| pc = preempt_count(); |
| resched = ftrace_preempt_disable(); |
| |
| cpu = raw_smp_processor_id(); |
| data = tr->data[cpu]; |
| disabled = atomic_inc_return(&data->disabled); |
| if (unlikely(disabled != 1)) |
| goto out; |
| |
| local_irq_save(flags); |
| __raw_spin_lock(&wakeup_lock); |
| |
| 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, ip, parent_ip, flags, pc); |
| |
| unlock: |
| __raw_spin_unlock(&wakeup_lock); |
| local_irq_restore(flags); |
| |
| out: |
| atomic_dec(&data->disabled); |
| |
| ftrace_preempt_enable(resched); |
| } |
| |
| static struct ftrace_ops trace_ops __read_mostly = |
| { |
| .func = wakeup_tracer_call, |
| }; |
| #endif /* CONFIG_FUNCTION_TRACER */ |
| |
| /* |
| * 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 |
| probe_wakeup_sched_switch(struct rq *rq, struct task_struct *prev, |
| struct task_struct *next) |
| { |
| unsigned long latency = 0, t0 = 0, t1 = 0; |
| struct trace_array_cpu *data; |
| cycle_t T0, T1, delta; |
| unsigned long flags; |
| long disabled; |
| int cpu; |
| int pc; |
| |
| tracing_record_cmdline(prev); |
| |
| 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; |
| |
| pc = preempt_count(); |
| |
| /* The task we are waiting for is waking up */ |
| data = wakeup_trace->data[wakeup_cpu]; |
| |
| /* disable local data, not wakeup_cpu data */ |
| cpu = raw_smp_processor_id(); |
| disabled = atomic_inc_return(&wakeup_trace->data[cpu]->disabled); |
| if (likely(disabled != 1)) |
| goto out; |
| |
| local_irq_save(flags); |
| __raw_spin_lock(&wakeup_lock); |
| |
| /* We could race with grabbing wakeup_lock */ |
| if (unlikely(!tracer_enabled || next != wakeup_task)) |
| goto out_unlock; |
| |
| trace_function(wakeup_trace, CALLER_ADDR1, CALLER_ADDR2, flags, pc); |
| tracing_sched_switch_trace(wakeup_trace, prev, next, flags, pc); |
| |
| /* |
| * 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(wakeup_trace, wakeup_task, wakeup_cpu); |
| |
| out_unlock: |
| __wakeup_reset(wakeup_trace); |
| __raw_spin_unlock(&wakeup_lock); |
| local_irq_restore(flags); |
| out: |
| atomic_dec(&wakeup_trace->data[cpu]->disabled); |
| } |
| |
| static void __wakeup_reset(struct trace_array *tr) |
| { |
| int cpu; |
| |
| for_each_possible_cpu(cpu) |
| tracing_reset(tr, cpu); |
| |
| 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; |
| |
| local_irq_save(flags); |
| __raw_spin_lock(&wakeup_lock); |
| __wakeup_reset(tr); |
| __raw_spin_unlock(&wakeup_lock); |
| local_irq_restore(flags); |
| } |
| |
| static void |
| probe_wakeup(struct rq *rq, struct task_struct *p, int success) |
| { |
| struct trace_array_cpu *data; |
| int cpu = smp_processor_id(); |
| unsigned long flags; |
| long disabled; |
| int pc; |
| |
| if (likely(!tracer_enabled)) |
| return; |
| |
| tracing_record_cmdline(p); |
| tracing_record_cmdline(current); |
| |
| if ((wakeup_rt && !rt_task(p)) || |
| p->prio >= wakeup_prio || |
| p->prio >= current->prio) |
| return; |
| |
| pc = preempt_count(); |
| disabled = atomic_inc_return(&wakeup_trace->data[cpu]->disabled); |
| if (unlikely(disabled != 1)) |
| goto out; |
| |
| /* interrupts should be off from try_to_wake_up */ |
| __raw_spin_lock(&wakeup_lock); |
| |
| /* check for races. */ |
| if (!tracer_enabled || p->prio >= wakeup_prio) |
| goto out_locked; |
| |
| /* reset the trace */ |
| __wakeup_reset(wakeup_trace); |
| |
| wakeup_cpu = task_cpu(p); |
| wakeup_prio = p->prio; |
| |
| wakeup_task = p; |
| get_task_struct(wakeup_task); |
| |
| local_save_flags(flags); |
| |
| data = wakeup_trace->data[wakeup_cpu]; |
| data->preempt_timestamp = ftrace_now(cpu); |
| tracing_sched_wakeup_trace(wakeup_trace, p, current, flags, pc); |
| trace_function(wakeup_trace, CALLER_ADDR1, CALLER_ADDR2, flags, pc); |
| |
| out_locked: |
| __raw_spin_unlock(&wakeup_lock); |
| out: |
| atomic_dec(&wakeup_trace->data[cpu]->disabled); |
| } |
| |
| static void start_wakeup_tracer(struct trace_array *tr) |
| { |
| int ret; |
| |
| ret = register_trace_sched_wakeup(probe_wakeup); |
| if (ret) { |
| pr_info("wakeup trace: Couldn't activate tracepoint" |
| " probe to kernel_sched_wakeup\n"); |
| return; |
| } |
| |
| ret = register_trace_sched_wakeup_new(probe_wakeup); |
| if (ret) { |
| pr_info("wakeup trace: Couldn't activate tracepoint" |
| " probe to kernel_sched_wakeup_new\n"); |
| goto fail_deprobe; |
| } |
| |
| ret = register_trace_sched_switch(probe_wakeup_sched_switch); |
| if (ret) { |
| pr_info("sched trace: Couldn't activate tracepoint" |
| " probe to kernel_sched_switch\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(); |
| |
| register_ftrace_function(&trace_ops); |
| |
| if (tracing_is_enabled()) |
| tracer_enabled = 1; |
| else |
| tracer_enabled = 0; |
| |
| return; |
| fail_deprobe_wake_new: |
| unregister_trace_sched_wakeup_new(probe_wakeup); |
| fail_deprobe: |
| unregister_trace_sched_wakeup(probe_wakeup); |
| } |
| |
| static void stop_wakeup_tracer(struct trace_array *tr) |
| { |
| tracer_enabled = 0; |
| unregister_ftrace_function(&trace_ops); |
| unregister_trace_sched_switch(probe_wakeup_sched_switch); |
| unregister_trace_sched_wakeup_new(probe_wakeup); |
| unregister_trace_sched_wakeup(probe_wakeup); |
| } |
| |
| static int __wakeup_tracer_init(struct trace_array *tr) |
| { |
| tracing_max_latency = 0; |
| wakeup_trace = tr; |
| start_wakeup_tracer(tr); |
| return 0; |
| } |
| |
| static int wakeup_tracer_init(struct trace_array *tr) |
| { |
| wakeup_rt = 0; |
| return __wakeup_tracer_init(tr); |
| } |
| |
| static int wakeup_rt_tracer_init(struct trace_array *tr) |
| { |
| wakeup_rt = 1; |
| return __wakeup_tracer_init(tr); |
| } |
| |
| static void wakeup_tracer_reset(struct trace_array *tr) |
| { |
| stop_wakeup_tracer(tr); |
| /* make sure we put back any tasks we are tracing */ |
| wakeup_reset(tr); |
| } |
| |
| static void wakeup_tracer_start(struct trace_array *tr) |
| { |
| wakeup_reset(tr); |
| tracer_enabled = 1; |
| } |
| |
| static void wakeup_tracer_stop(struct trace_array *tr) |
| { |
| tracer_enabled = 0; |
| } |
| |
| static struct tracer wakeup_tracer __read_mostly = |
| { |
| .name = "wakeup", |
| .init = wakeup_tracer_init, |
| .reset = wakeup_tracer_reset, |
| .start = wakeup_tracer_start, |
| .stop = wakeup_tracer_stop, |
| .print_max = 1, |
| #ifdef CONFIG_FTRACE_SELFTEST |
| .selftest = trace_selftest_startup_wakeup, |
| #endif |
| }; |
| |
| static struct tracer wakeup_rt_tracer __read_mostly = |
| { |
| .name = "wakeup_rt", |
| .init = wakeup_rt_tracer_init, |
| .reset = wakeup_tracer_reset, |
| .start = wakeup_tracer_start, |
| .stop = wakeup_tracer_stop, |
| .wait_pipe = poll_wait_pipe, |
| .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; |
| |
| ret = register_tracer(&wakeup_rt_tracer); |
| if (ret) |
| return ret; |
| |
| return 0; |
| } |
| device_initcall(init_wakeup_tracer); |