linux-kernel - Re: [PATCH 1/3] tracing/ftrace: don't insert TRACE

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Date:	Thu, 4 Dec 2008 18:26:44 -0500 (EST)
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Frédéric Weisbecker <fweisbec@...il.com>
cc:	Ingo Molnar <mingo@...e.hu>,
	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] tracing/ftrace: don't insert TRACE_PRINT during
 selftests


On Fri, 5 Dec 2008, Fr?d?ric Weisbecker wrote:
> >
> > Enable this in the mutex lock, and we could make it a normal int.
> >
> 
> 
> But ftrace_printk can be called from interrupt context. I think we can loose
> some TRACE_PRINT entries at the selftests time since the tracer are not enabled
> by the user at this time, except the boot tracer...

I mean, move it down farther after we acquire the mutex. Should be fine.

-- Steve

> 
> >>               /*
> >>                * Run a selftest on this tracer.
> >>                * Here we reset the trace buffer, and set the current
> >> @@ -603,6 +613,7 @@ int register_tracer(struct tracer *type)
> >>               /* the test is responsible for initializing and enabling */
> >>               pr_info("Testing tracer %s: ", type->name);
> >>               ret = type->selftest(type, tr);
> >> +             atomic_set(&tracing_selftest_running, 0);
> >>               /* the test is responsible for resetting too */
> >>               current_trace = saved_tracer;
> >>               if (ret) {
> >> @@ -3594,7 +3605,7 @@ int trace_vprintk(unsigned long ip, int depth, const char *fmt, va_list args)
> >>       unsigned long flags, irq_flags;
> >>       int cpu, len = 0, size, pc;
> >>
> >> -     if (tracing_disabled)
> >> +     if (tracing_disabled || atomic_read(&tracing_selftest_running))
> >>               return 0;
> >>
> >>       pc = preempt_count();
> >> --
> >
> > -- Steve
> >
> >
> 
> 
--
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