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

From: Michal Simek
Date: Wed Jul 28 2010 - 01:27:17 EST

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 Simek, Ing. (M.Eng)
w: p: +42-0-721842854
Maintainer of Linux kernel 2.6 Microblaze Linux -
Microblaze U-BOOT custodian
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