Hi William,

 You're right. As you suggest I reverted memory barrier part. Also,
added memory barriers while allocating and freeing memory.

Can you confirm that if it's okay now or missed anything else ?

PS. I couldn't figure out how to reverse function of hotcpu_notifier.
That's why I used  register_cpu_notifier and #ifdefs.



On 6/27/05, William Lee Irwin III <wli@holomorphy.com> wrote:
> On Mon, Jun 27, 2005 at 03:13:13PM +0300, Levent Serinol wrote:
> > +#ifdef CONFIG_SMP
> > +int remove_hash_tables(void)
> > +{
> > +     int cpu;
> > +
> > +
> > +     for_each_online_cpu(cpu) {
> > +             struct page *page;
> > +
> > +             if (per_cpu(cpu_profile_hits, cpu)[0]) {
> > +                     page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]);
> > +                     per_cpu(cpu_profile_hits, cpu)[0] = NULL;
> > +                     __free_page(page);
> > +             }
> > +             if (per_cpu(cpu_profile_hits, cpu)[1]) {
> > +                     page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
> > +                     per_cpu(cpu_profile_hits, cpu)[1] = NULL;
> > +                     __free_page(page);
> > +             }
> > +     }
> > +     return -1;
> 
> Big problem. Timer interrupts can be firing while this is in progress.
> The reason for profile_nop() is so that the code I have running during
> timer interrupts (protected by local_irq_save()) runs to completion,
> where it will afterward discover the flags or variables set to updated
> states. You'll probably have to add more (e.g. memory barriers) since
> you can tolerate less once you're dynamically allocating and freeing etc.
> 
> 
> On Mon, Jun 27, 2005 at 03:13:13PM +0300, Levent Serinol wrote:
> > @@ -560,7 +668,11 @@ static int __init create_proc_profile(vo
> >               return 0;
> >       entry->proc_fops = &proc_profile_operations;
> >       entry->size = (1+prof_len) * sizeof(atomic_t);
> > -     hotcpu_notifier(profile_cpu_callback, 0);
> > +#ifdef CONFIG_HOTPLUG_CPU
> > +     register_cpu_notifier(&profile_cpu_notifier);
> > +#endif
> > +     profile_params[0] = prof_on;
> > +     profile_params[1] = prof_shift;
> >       return 0;
> >  }
> >  module_init(create_proc_profile);
> 
> hotcpu_notifier() is there to avoid the #ifdef; you shouldn't need to
> rearrange that.
> 
> Anyway, just keep fixing it up. There should be a few more after this.
> 
> 
> -- wli
> 


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