Re: [RFC][PATCH 4/5 v2] printk: Add per_cpu printk func to allow printk to be diverted

[Steven Rostedt]

On Fri, 27 Jun 2014 16:20:25 +0200
Petr MlÃdek <pmladek@xxxxxxx> wrote:


> >  	va_start(args, fmt);
> > -	r = vprintk_emit(0, -1, NULL, 0, fmt, args);
> > +	preempt_disable();
> 
> I think that it is too late to disable the preemption here.
> It has to be done by the printk() caller if it wants to be sure
> that the requested function is used.

That's only if the printk() caller cares. But it would be nice that we
run the printk_func for the CPU that vprintk_func() is on, thus the
preempt_disable() is required. (in -rt, this would turn into a
migrate_disable()).

-- Steve

> 
> > +	vprintk_func = this_cpu_read(printk_func);
> > +	r = vprintk_func(fmt, args);
> > +	preempt_enable();
> >  	va_end(args);
> >  
> >  	return r;
> 
> Best Regards,
> Petr

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