Re: [PATCH] asm-generic: Use raw_local_irq_save/restore instead local_irq_save/restore

Michal Simek
2010-07-28T05:27:14Z

Mike Frysinger wrote:
> On Tue, Jul 27, 2010 at 19:18, Andrew Morton wrote:
>> On Mon, 26 Jul 2010 10:49:50 +0200 Michal Simek wrote:
>>> 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.
>> Seems that this will also affect blackfin, mn10300 and score. I guess
>> they aren't supporting tracing yet?
>
> do you mean TRACE_IRQFLAGS_SUPPORT ? Blackfin should ... my
> understanding was that arches just needed to implement asm/irqflags.h
> for it.

Blackin uses own include/asm/atomic.h implementation where shouldn't be
a problem with irqflags tracer. Look at my second post.

Michal

--
Michal Simek, Ing. (M.Eng)
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel 2.6 Microblaze Linux - http://www.monstr.eu/fdt/
Microblaze U-BOOT custodian