Re: [PATCH] Fix dirty page accounting in redirty_page_for_writepage()

Ingo Molnar
2009-04-30T14:16:58Z

* Christoph Lameter <cl@linux.com> wrote:

> On Thu, 30 Apr 2009, Ingo Molnar wrote:
>
> > it's all done, implemented and upstream already. You are a bit late
> > to the party ;-)
>
> Just looked over it. Yep, now we just need to fix the things that
> were messed up.

Could we please skip over the lengthy flamewar and bad-mouthing of
other people's work and go straight to the constructive portion of
the discussion? ;-)

The patch below makes the fallback/slowpath irq safe.

Ingo

diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index 1581ff2..6b3984a 100644
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -139,17 +139,23 @@ static inline void free_percpu(void *p)
#ifndef percpu_read
# define percpu_read(var) \
({ \
+ unsigned long flags; \
typeof(per_cpu_var(var)) __tmp_var__; \
- __tmp_var__ = get_cpu_var(var); \
- put_cpu_var(var); \
+ \
+ local_irq_save(flags); \
+ __tmp_var__ = __get_cpu_var(var); \
+ local_irq_restore(flags); \
__tmp_var__; \
})
#endif

#define __percpu_generic_to_op(var, val, op) \
do { \
- get_cpu_var(var) op val; \
- put_cpu_var(var); \
+ unsigned long flags; \
+ \
+ local_irq_save(flags); \
+ op val; \
+ local_irq_restore(flags); \
} while (0)

#ifndef percpu_write