Re: [Linux-ia64] ia64_mca_rendez_int_handler use of hard_smp_processor_id

From: Keith Owens <kaos_at_sgi.com>
Date: 2003-03-26 08:15:30
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 =3D cpu_logical_id(hard_smp_processor_id());
>  Keith> #endif
>  Keith> ia64_mc_info.imi_rendez_checkin[cpu] =3D =
>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 =3D 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
Received on Tue Mar 25 13:16:00 2003

This archive was generated by hypermail 2.1.8 : 2005-08-02 09:20:12 EST