Messages in this thread | | | Date | Wed, 26 May 2010 10:08:05 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] asm-generic: Use raw_local_irq_save/restore instead local_irq_save/restore |
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On Wed, 26 May 2010 10:42:43 -0400 Steven Rostedt <rostedt@goodmis.org> wrote:
> On Wed, 2010-05-26 at 10:48 +0200, monstr@monstr.eu wrote: > > From: Michal Simek <monstr@monstr.eu> > > > > start/stop_critical_timing function for preemptirqsoff, preemptoff > > and irqsoff tracers contains atomic_inc and atomic_dec operations. > > > > Atomic operations used local_irq_save/restore macros to ensure > > atomic access but they are traced by the same function which is causing > > recursion problem. > > > > The reason is when these tracers are turn ON then local_irq_save/restore > > macros are changed in include/linux/irqflags.h to call trace_hardirqs_on/off > > which call start/stop_critical_timing. > > > > Microblaze was affected because use generic atomic implementation. > > > > Signed-off-by: Michal Simek <monstr@monstr.eu> > > Acked-by: Steven Rostedt <rostedt@goodmis.org> >
Sighed-at-by: me.
> > diff --git a/include/asm-generic/atomic.h b/include/asm-generic/atomic.h > > index 058129e..6c190fd 100644 > > --- a/include/asm-generic/atomic.h > > +++ b/include/asm-generic/atomic.h > > @@ -57,11 +57,11 @@ static inline int atomic_add_return(int i, atomic_t *v) > > unsigned long flags; > > int temp; > > > > - local_irq_save(flags); > > + raw_local_irq_save(flags); > > temp = v->counter; > > temp += i; > > v->counter = temp; > > - local_irq_restore(flags); > > + raw_local_irq_restore(flags); > > > > return temp; > > }
If a developer looks at atomic_add_return() and asks himself "why did this use raw_local_irq_save()", the only way of answering that question is to go groveling through the git logs, which is a right PITA if you're trying to get some coding work done.
Guys, any time you add code which is non-obvious at the raw C level, it *needs* a comment!
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