* Re: [Linux-ia64] ia64_mca_rendez_int_handler use of hard_smp_processor_id
2003-03-22 4:12 [Linux-ia64] ia64_mca_rendez_int_handler use of hard_smp_processor_id Keith Owens
@ 2003-03-24 21:54 ` David Mosberger
2003-03-25 16:45 ` Luck, Tony
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: David Mosberger @ 2003-03-24 21:54 UTC (permalink / raw)
To: linux-ia64
>>>>> On Sat, 22 Mar 2003 15:12:55 +1100, Keith Owens <kaos@sgi.com> said:
Keith> arch/ia64/kernel/mca.c:ia64_mca_rendez_int_handler has
Keith> #ifdef CONFIG_SMP
Keith> cpu = cpu_logical_id(hard_smp_processor_id());
Keith> #endif
Keith> ia64_mc_info.imi_rendez_checkin[cpu] = IA64_MCA_RENDEZ_CHECKIN_DONE;
Keith> All the other code that runs imi_rendez_checkin does so using logical
Keith> cpu numbers. Why does ia64_mca_rendez_int_handler use that convoluted
Keith> expression instead of the simpler
Keith> cpu = smp_processor_id();
I don't know either. Perhaps the original author remembers (Jenna or
Tony, perhaps?).
--david
^ permalink raw reply [flat|nested] 6+ messages in thread* RE: [Linux-ia64] ia64_mca_rendez_int_handler use of hard_smp_processor_id
2003-03-22 4:12 [Linux-ia64] ia64_mca_rendez_int_handler use of hard_smp_processor_id Keith Owens
2003-03-24 21:54 ` David Mosberger
@ 2003-03-25 16:45 ` Luck, Tony
2003-03-25 21:15 ` Keith Owens
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Luck, Tony @ 2003-03-25 16:45 UTC (permalink / raw)
To: linux-ia64
>>>>> On Sat, 22 Mar 2003 15:12:55 +1100, Keith Owens <kaos@sgi.com> said:
Keith> arch/ia64/kernel/mca.c:ia64_mca_rendez_int_handler has
Keith> #ifdef CONFIG_SMP
Keith> cpu = cpu_logical_id(hard_smp_processor_id());
Keith> #endif
Keith> ia64_mc_info.imi_rendez_checkin[cpu] = IA64_MCA_RENDEZ_CHECKIN_DONE;
Keith> All the other code that runs imi_rendez_checkin does so using logical
Keith> cpu numbers. Why does ia64_mca_rendez_int_handler use that convoluted
Keith> expression instead of the simpler
Keith> cpu = smp_processor_id();
David> I don't know either. Perhaps the original author remembers (Jenna or
David> Tony, perhaps?).
This code predates me. I checked with Jenna and she says that it's before
her time too.
<speculation>
That convoluted expression avoids use of the per-cpu mapping, but I can't see
why we'd be scared to use that here, and not be paranoid elsewhere. How was
smp_processor_id() implemented far back in days of 2.4.0 and before?
</speculation>
-Tony
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [Linux-ia64] ia64_mca_rendez_int_handler use of hard_smp_processor_id
2003-03-22 4:12 [Linux-ia64] ia64_mca_rendez_int_handler use of hard_smp_processor_id Keith Owens
2003-03-24 21:54 ` David Mosberger
2003-03-25 16:45 ` Luck, Tony
@ 2003-03-25 21:15 ` Keith Owens
2003-03-26 1:55 ` Peter Chubb
2003-04-16 16:36 ` Bjorn Helgaas
4 siblings, 0 replies; 6+ messages in thread
From: Keith Owens @ 2003-03-25 21:15 UTC (permalink / raw)
To: linux-ia64
On Tue, 25 Mar 2003 08:45:56 -0800,
"Luck, Tony" <tony.luck@intel.com> wrote:
>>>>>> On Sat, 22 Mar 2003 15:12:55 +1100, Keith Owens <kaos@sgi.com> >said:
>
> Keith> arch/ia64/kernel/mca.c:ia64_mca_rendez_int_handler has
> Keith> #ifdef CONFIG_SMP
> Keith> cpu = cpu_logical_id(hard_smp_processor_id());
> Keith> #endif
> Keith> ia64_mc_info.imi_rendez_checkin[cpu] = >IA64_MCA_RENDEZ_CHECKIN_DONE;
>
> Keith> All the other code that runs imi_rendez_checkin does so using >logical
> Keith> cpu numbers. Why does ia64_mca_rendez_int_handler use that >convoluted
> Keith> expression instead of the simpler
> Keith> cpu = smp_processor_id();
>
> David> I don't know either. Perhaps the original author remembers >(Jenna or
> David> Tony, perhaps?).
>
>This code predates me. I checked with Jenna and she says that it's >before
>her time too.
>
><speculation>
>That convoluted expression avoids use of the per-cpu mapping, but I >can't see
>why we'd be scared to use that here, and not be paranoid elsewhere. How >was
>smp_processor_id() implemented far back in days of 2.4.0 and before?
></speculation>
At one time there was confusion between which arrays used the logical
cpu number in smp_processor_id() and which arrays used the hardware cpu
number. This is probably a holdover from that period.
Index: 20.5/arch/ia64/kernel/mca.c
--- 20.5/arch/ia64/kernel/mca.c Wed, 11 Dec 2002 20:58:53 +1100 kaos (linux-2.4/s/c/5_mca.c 1.1.3.2.3.1.1.1.1.3 644)
+++ 20.5(w)/arch/ia64/kernel/mca.c Wed, 26 Mar 2003 08:14:29 +1100 kaos (linux-2.4/s/c/5_mca.c 1.1.3.2.3.1.1.1.1.3 644)
@@ -640,13 +640,10 @@ ia64_mca_wakeup_all(void)
void
ia64_mca_rendez_int_handler(int rendez_irq, void *arg, struct pt_regs *ptregs)
{
- int flags, cpu = 0;
+ int flags, cpu = smp_processor_id();
/* Mask all interrupts */
save_and_cli(flags);
-#ifdef CONFIG_SMP
- cpu = cpu_logical_id(hard_smp_processor_id());
-#endif
ia64_mc_info.imi_rendez_checkin[cpu] = IA64_MCA_RENDEZ_CHECKIN_DONE;
/* Register with the SAL monarch that the slave has
* reached SAL
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [Linux-ia64] ia64_mca_rendez_int_handler use of hard_smp_processor_id
2003-03-22 4:12 [Linux-ia64] ia64_mca_rendez_int_handler use of hard_smp_processor_id Keith Owens
` (2 preceding siblings ...)
2003-03-25 21:15 ` Keith Owens
@ 2003-03-26 1:55 ` Peter Chubb
2003-04-16 16:36 ` Bjorn Helgaas
4 siblings, 0 replies; 6+ messages in thread
From: Peter Chubb @ 2003-03-26 1:55 UTC (permalink / raw)
To: linux-ia64
Index: 20.5/arch/ia64/kernel/mca.c
--- 20.5/arch/ia64/kernel/mca.c Wed, 11 Dec 2002 20:58:53 +1100 kaos (linux-2.4/s/c/5_mca.c 1.1.3.2.3.1.1.1.1.3 644)
+++ 20.5(w)/arch/ia64/kernel/mca.c Wed, 26 Mar 2003 08:14:29 +1100 kaos (linux-2.4/s/c/5_mca.c 1.1.3.2.3.1.1.1.1.3 644)
@@ -640,13 +640,10 @@ ia64_mca_wakeup_all(void)
void
ia64_mca_rendez_int_handler(int rendez_irq, void *arg, struct pt_regs *ptregs)
{
- int flags, cpu = 0;
+ int flags, cpu = smp_processor_id();
/* Mask all interrupts */
save_and_cli(flags);
If this is called from a preemptible context, then move the cpu cmp_processor_id() within the save_and_cli() section, or it won't be
preempt safe. (thread could be migrated between getting the processor
ID and stopping interrupts.)
Peter C
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [Linux-ia64] ia64_mca_rendez_int_handler use of hard_smp_processor_id
2003-03-22 4:12 [Linux-ia64] ia64_mca_rendez_int_handler use of hard_smp_processor_id Keith Owens
` (3 preceding siblings ...)
2003-03-26 1:55 ` Peter Chubb
@ 2003-04-16 16:36 ` Bjorn Helgaas
4 siblings, 0 replies; 6+ messages in thread
From: Bjorn Helgaas @ 2003-04-16 16:36 UTC (permalink / raw)
To: linux-ia64
I applied this for 2.4.
On Tuesday 25 March 2003 2:15 pm, Keith Owens wrote:
> Index: 20.5/arch/ia64/kernel/mca.c
> --- 20.5/arch/ia64/kernel/mca.c Wed, 11 Dec 2002 20:58:53 +1100 kaos (linux-2.4/s/c/5_mca.c 1.1.3.2.3.1.1.1.1.3 644)
> +++ 20.5(w)/arch/ia64/kernel/mca.c Wed, 26 Mar 2003 08:14:29 +1100 kaos (linux-2.4/s/c/5_mca.c 1.1.3.2.3.1.1.1.1.3 644)
> @@ -640,13 +640,10 @@ ia64_mca_wakeup_all(void)
> void
> ia64_mca_rendez_int_handler(int rendez_irq, void *arg, struct pt_regs *ptregs)
> {
> - int flags, cpu = 0;
> + int flags, cpu = smp_processor_id();
> /* Mask all interrupts */
> save_and_cli(flags);
>
> -#ifdef CONFIG_SMP
> - cpu = cpu_logical_id(hard_smp_processor_id());
> -#endif
> ia64_mc_info.imi_rendez_checkin[cpu] = IA64_MCA_RENDEZ_CHECKIN_DONE;
> /* Register with the SAL monarch that the slave has
> * reached SAL
^ permalink raw reply [flat|nested] 6+ messages in thread