From: Zwane Mwaikambo <zwane@linuxpower.ca>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@osdl.org>,
Nathan Lynch <nathanl@austin.ibm.com>,
Srivatsa Vaddagiri <vatsa@in.ibm.com>
Subject: [PATCH] Hotplug cpu: Fix APIC queued timer vector race #2
Date: Mon, 23 Aug 2004 04:41:49 -0400 (EDT) [thread overview]
Message-ID: <Pine.LNX.4.58.0408230435240.27390@montezuma.fsmlabs.com> (raw)
In-Reply-To: <1093223788.4888.213.camel@bach>
On Mon, 23 Aug 2004, Rusty Russell wrote:
> On Mon, 2004-08-23 at 00:47, Zwane Mwaikambo wrote:
> > On Sun, 22 Aug 2004, Rusty Russell wrote:
> >
> > > On Sun, 2004-08-22 at 00:10, Zwane Mwaikambo wrote:
> > > > Some timer interrupt vectors were queued on the Local APIC and were being
> > > > serviced when we enabled interrupts again in fixup_irqs(), so we need to
> > > > mask the APIC timer, enable interrupts so that any queued interrupts get
> > > > processed whilst the processor is still on the online map and then clear
> > > > ourselves from the online map. 1ms is a nice safe number even under heavy
> > > > interrupt load with higher priority vectors queued. Andrew this is
> > > > the patch i promised, Rusty, i'm not sure if you find
> > > > __attribute__((weak)) offensive...
> > >
> > > It's horrible. Please move the unsetting of the cpu_online bit into the
> > > arch-specific __cpu_disable() code for each arch, which is consistent
> > > and also simplifies things.
Ok this should be the last one, against 2.6.8.1-mm4.
arch/i386/kernel/smpboot.c | 21 +++++++++------------
arch/ia64/kernel/smpboot.c | 3 ++-
arch/ppc64/kernel/smp.c | 4 +++-
arch/s390/kernel/smp.c | 4 +++-
kernel/cpu.c | 21 +++++----------------
5 files changed, 22 insertions(+), 31 deletions(-)
Signed-off-by: Zwane Mwaikambo <zwane@linuxpower.ca>
Index: linux-2.6.8.1-mm4/kernel/cpu.c
===================================================================
RCS file: /home/cvsroot/linux-2.6.8.1-mm4/kernel/cpu.c,v
retrieving revision 1.1.1.1
diff -u -p -B -r1.1.1.1 cpu.c
--- linux-2.6.8.1-mm4/kernel/cpu.c 23 Aug 2004 08:24:54 -0000 1.1.1.1
+++ linux-2.6.8.1-mm4/kernel/cpu.c 23 Aug 2004 08:32:01 -0000
@@ -84,31 +84,20 @@ static int cpu_run_sbin_hotplug(unsigned
return call_usermodehelper(argv[0], argv, envp, 0);
}
-void __attribute__((weak)) __cpu_prep_disable(void)
-{
-}
-
/* Take this CPU down. */
static int take_cpu_down(void *unused)
{
int err;
- /* Prepatory work before clearing the cpu off the online map */
- __cpu_prep_disable();
-
- /* Take offline: makes arch_cpu_down somewhat easier. */
- cpu_clear(smp_processor_id(), cpu_online_map);
-
/* Ensure this CPU doesn't handle any more interrupts. */
err = __cpu_disable();
if (err < 0)
- cpu_set(smp_processor_id(), cpu_online_map);
- else
- /* Force idle task to run as soon as we yield: it should
- immediately notice cpu is offline and die quickly. */
- sched_idle_next();
+ return err;
- return err;
+ /* Force idle task to run as soon as we yield: it should
+ immediately notice cpu is offline and die quickly. */
+ sched_idle_next();
+ return 0;
}
int cpu_down(unsigned int cpu)
Index: linux-2.6.8.1-mm4/arch/i386/kernel/smpboot.c
===================================================================
RCS file: /home/cvsroot/linux-2.6.8.1-mm4/arch/i386/kernel/smpboot.c,v
retrieving revision 1.1.1.1
diff -u -p -B -r1.1.1.1 smpboot.c
--- linux-2.6.8.1-mm4/arch/i386/kernel/smpboot.c 23 Aug 2004 08:23:22 -0000 1.1.1.1
+++ linux-2.6.8.1-mm4/arch/i386/kernel/smpboot.c 23 Aug 2004 08:32:01 -0000
@@ -1159,18 +1159,6 @@ static int __devinit cpu_enable(unsigned
return 0;
}
-void __cpu_prep_disable(void)
-{
- /* We enable the timer again on the exit path of the death loop */
- if (smp_processor_id() != 0) {
- disable_APIC_timer();
- /* Allow any queued timer interrupts to get serviced */
- local_irq_enable();
- mdelay(1);
- local_irq_disable();
- }
-}
-
int __cpu_disable(void)
{
/*
@@ -1184,6 +1172,15 @@ int __cpu_disable(void)
if (smp_processor_id() == 0)
return -EBUSY;
+ /* We enable the timer again on the exit path of the death loop */
+ disable_APIC_timer();
+ /* Allow any queued timer interrupts to get serviced */
+ local_irq_enable();
+ mdelay(1);
+ local_irq_disable();
+
+ /* It's now safe to remove this processor from the online map */
+ cpu_clear(smp_processor_id(), cpu_online_map);
fixup_irqs();
return 0;
}
Index: linux-2.6.8.1-mm4/arch/ia64/kernel/smpboot.c
===================================================================
RCS file: /home/cvsroot/linux-2.6.8.1-mm4/arch/ia64/kernel/smpboot.c,v
retrieving revision 1.1.1.1
diff -u -p -B -r1.1.1.1 smpboot.c
--- linux-2.6.8.1-mm4/arch/ia64/kernel/smpboot.c 23 Aug 2004 08:23:31 -0000 1.1.1.1
+++ linux-2.6.8.1-mm4/arch/ia64/kernel/smpboot.c 23 Aug 2004 08:32:01 -0000
@@ -591,9 +591,10 @@ int __cpu_disable(void)
if (cpu == 0)
return -EBUSY;
+ cpu_clear(cpu, cpu_online_map);
fixup_irqs();
local_flush_tlb_all();
- printk ("Disabled cpu %u\n", smp_processor_id());
+ printk("Disabled cpu %u\n", cpu);
return 0;
}
Index: linux-2.6.8.1-mm4/arch/ppc64/kernel/smp.c
===================================================================
RCS file: /home/cvsroot/linux-2.6.8.1-mm4/arch/ppc64/kernel/smp.c,v
retrieving revision 1.1.1.1
diff -u -p -B -r1.1.1.1 smp.c
--- linux-2.6.8.1-mm4/arch/ppc64/kernel/smp.c 23 Aug 2004 08:23:34 -0000 1.1.1.1
+++ linux-2.6.8.1-mm4/arch/ppc64/kernel/smp.c 23 Aug 2004 08:32:01 -0000
@@ -254,11 +254,13 @@ int __cpu_disable(void)
{
/* FIXME: go put this in a header somewhere */
extern void xics_migrate_irqs_away(void);
+ int cpu = smp_processor_id();
+ cpu_clear(cpu, cpu_online_map);
systemcfg->processorCount--;
/*fix boot_cpuid here*/
- if (smp_processor_id() == boot_cpuid)
+ if (cpu == boot_cpuid)
boot_cpuid = any_online_cpu(cpu_online_map);
/* FIXME: abstract this to not be platform specific later on */
Index: linux-2.6.8.1-mm4/arch/s390/kernel/smp.c
===================================================================
RCS file: /home/cvsroot/linux-2.6.8.1-mm4/arch/s390/kernel/smp.c,v
retrieving revision 1.1.1.1
diff -u -p -B -r1.1.1.1 smp.c
--- linux-2.6.8.1-mm4/arch/s390/kernel/smp.c 23 Aug 2004 08:23:39 -0000 1.1.1.1
+++ linux-2.6.8.1-mm4/arch/s390/kernel/smp.c 23 Aug 2004 08:32:01 -0000
@@ -682,13 +682,15 @@ __cpu_disable(void)
{
unsigned long flags;
ec_creg_mask_parms cr_parms;
+ int cpu = smp_processor_id();
spin_lock_irqsave(&smp_reserve_lock, flags);
- if (smp_cpu_reserved[smp_processor_id()] != 0) {
+ if (smp_cpu_reserved[cpu] != 0) {
spin_unlock_irqrestore(&smp_reserve_lock, flags);
return -EBUSY;
}
+ cpu_clear(cpu, cpu_online_map);
/* disable all external interrupts */
cr_parms.start_ctl = 0;
prev parent reply other threads:[~2004-08-23 8:37 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-08-21 14:10 [PATCH][2.6] Hotplug cpu: Fix APIC queued timer vector race Zwane Mwaikambo
2004-08-22 3:32 ` Rusty Russell
2004-08-22 14:47 ` Zwane Mwaikambo
2004-08-22 15:00 ` Zwane Mwaikambo
2004-08-23 1:16 ` Rusty Russell
2004-08-23 8:41 ` Zwane Mwaikambo [this message]
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