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ftrace: make some tracers reentrant
Now that the ring buffer is reentrant, some of the ftrace tracers (sched_swich, debugging traces) can also be reentrant. Note: Never make the function tracer reentrant, that can cause recursion problems all over the kernel. The function tracer must disable reentrancy. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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@ -839,7 +839,6 @@ ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3)
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{
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struct trace_array *tr = &global_trace;
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struct trace_array_cpu *data;
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long disabled;
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int cpu;
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int pc;
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@ -850,12 +849,10 @@ ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3)
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preempt_disable_notrace();
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cpu = raw_smp_processor_id();
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data = tr->data[cpu];
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disabled = atomic_inc_return(&data->disabled);
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if (likely(disabled == 1))
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if (likely(!atomic_read(&data->disabled)))
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ftrace_trace_special(tr, data, arg1, arg2, arg3, pc);
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atomic_dec(&data->disabled);
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preempt_enable_notrace();
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}
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@ -2961,7 +2958,6 @@ int trace_vprintk(unsigned long ip, const char *fmt, va_list args)
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struct trace_array_cpu *data;
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struct print_entry *entry;
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unsigned long flags, irq_flags;
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long disabled;
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int cpu, len = 0, size, pc;
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if (!tr->ctrl || tracing_disabled)
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@ -2971,9 +2967,8 @@ int trace_vprintk(unsigned long ip, const char *fmt, va_list args)
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preempt_disable_notrace();
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cpu = raw_smp_processor_id();
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data = tr->data[cpu];
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disabled = atomic_inc_return(&data->disabled);
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if (unlikely(disabled != 1))
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if (unlikely(atomic_read(&data->disabled)))
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goto out;
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spin_lock_irqsave(&trace_buf_lock, flags);
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@ -2999,7 +2994,6 @@ int trace_vprintk(unsigned long ip, const char *fmt, va_list args)
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spin_unlock_irqrestore(&trace_buf_lock, flags);
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out:
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atomic_dec(&data->disabled);
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preempt_enable_notrace();
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return len;
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@ -24,7 +24,6 @@ probe_sched_switch(struct rq *__rq, struct task_struct *prev,
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{
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struct trace_array_cpu *data;
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unsigned long flags;
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long disabled;
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int cpu;
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int pc;
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@ -41,12 +40,10 @@ probe_sched_switch(struct rq *__rq, struct task_struct *prev,
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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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disabled = atomic_inc_return(&data->disabled);
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if (likely(disabled == 1))
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if (likely(!atomic_read(&data->disabled)))
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tracing_sched_switch_trace(ctx_trace, data, prev, next, flags, pc);
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atomic_dec(&data->disabled);
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local_irq_restore(flags);
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}
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@ -55,7 +52,6 @@ probe_sched_wakeup(struct rq *__rq, struct task_struct *wakee)
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{
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struct trace_array_cpu *data;
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unsigned long flags;
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long disabled;
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int cpu, pc;
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if (!likely(tracer_enabled))
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@ -67,13 +63,11 @@ probe_sched_wakeup(struct rq *__rq, struct task_struct *wakee)
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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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disabled = atomic_inc_return(&data->disabled);
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if (likely(disabled == 1))
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if (likely(!atomic_read(&data->disabled)))
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tracing_sched_wakeup_trace(ctx_trace, data, wakee, current,
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flags, pc);
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atomic_dec(&data->disabled);
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local_irq_restore(flags);
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}
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