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Message-ID: <4FB0197F.6010000@linux.vnet.ibm.com>
Date: Mon, 14 May 2012 01:58:47 +0530
From: "Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
To: John David Anglin <dave.anglin@...l.net>
CC: Linus Torvalds <torvalds@...ux-foundation.org>,
"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
Ingo Molnar <mingo@...nel.org>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Mikulas Patocka <mpatocka@...hat.com>, stepanm@...eaurora.org,
Thomas Gleixner <tglx@...utronix.de>,
James.Bottomley@...senpartnership.com, deller@....de,
dhowells@...hat.com, yasutake.koichi@...panasonic.com,
eike-kernel@...tec.de, linux-parisc@...r.kernel.org,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: Linux 3.4-rc7
On 05/14/2012 01:38 AM, John David Anglin wrote:
> On 13-May-12, at 3:56 PM, Srivatsa S. Bhat wrote:
>
>> The regression was introduced in the 3.4 merge window itself (by commit
>> 5fbd036b55 "sched: Cleanup cpu_active madness").
>>
>> Links to the original posting:
>> PA_RISC: http://marc.info/?l=linux-parisc&m=133241790810604&w=2
>
>
> If I had the above change, I get
>
> CHK include/generated/compile.h
> CC arch/parisc/kernel/smp.o
> arch/parisc/kernel/smp.c: In function 'smp_cpu_init':
> arch/parisc/kernel/smp.c:300:2: error: implicit declaration of function
> 'notify_cpu_starting' [-Werror=implicit-function-declaration]
> cc1: some warnings being treated as errors
> make[1]: *** [arch/parisc/kernel/smp.o] Error 1
>
Sorry about that. I neither have the hardware nor the toolchain
to test it. I guess this problem doesn't exist for mn10300 since it
already includes linux/cpu.h when CONFIG_HOTPLUG_CPU=y
Does the below updated patch help for PA-RISC?
----
From: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com>
parisc/CPU hotplug: Add missing call to notify_cpu_starting()
The scheduler depends on receiving the CPU_STARTING notification, without
which we end up into a lot of trouble. So add the missing call to
notify_cpu_starting() in the bringup code.
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com>
---
arch/parisc/kernel/smp.c | 8 +++++++-
1 files changed, 7 insertions(+), 1 deletions(-)
diff --git a/arch/parisc/kernel/smp.c b/arch/parisc/kernel/smp.c
index 0bb1d63..4dc7b79 100644
--- a/arch/parisc/kernel/smp.c
+++ b/arch/parisc/kernel/smp.c
@@ -31,6 +31,7 @@
#include <linux/delay.h>
#include <linux/bitops.h>
#include <linux/ftrace.h>
+#include <linux/cpu.h>
#include <linux/atomic.h>
#include <asm/current.h>
@@ -295,8 +296,13 @@ smp_cpu_init(int cpunum)
printk(KERN_CRIT "CPU#%d already initialized!\n", cpunum);
machine_halt();
- }
+ }
+
+ notify_cpu_starting(cpunum);
+
+ ipi_call_lock();
set_cpu_online(cpunum, true);
+ ipi_call_unlock();
/* Initialise the idle task for this CPU */
atomic_inc(&init_mm.mm_count);
--
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