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SubjectRe: [PATCH] x86/oprofile: disable preemption in nmi_shutdown
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Hi,

On Sun, Jun 22, 2008 at 9:30 AM, Johannes Weiner <hannes@saeurebad.de> wrote:
> Vegard Nossum <vegard.nossum@gmail.com> writes:
>> static void nmi_shutdown(void)
>> {
>> - struct op_msrs *msrs = &__get_cpu_var(cpu_msrs);
>> + struct op_msrs *msrs;
>> +
>> + preempt_disable();
>> + msrs = &__get_cpu_var(cpu_msrs);
>> nmi_enabled = 0;
>> on_each_cpu(nmi_cpu_shutdown, NULL, 0, 1);
>> unregister_die_notifier(&profile_exceptions_nb);
>> model->shutdown(msrs);
>> free_msrs();
>> + preempt_enable();
>
> Have a look at get_cpu_var() and put_cpu_var(), that is exactly the
> pattern.

Thanks! How about this instead?


Vegard


From: Vegard Nossum <vegard.nossum@gmail.com>
Date: Sat, 21 Jun 2008 23:44:19 +0200
Subject: [PATCH] x86/oprofile: disable preemption in nmi_shutdown

BUG: using smp_processor_id() in preemptible [00000000] code: oprofiled/27301
caller is nmi_shutdown+0x11/0x60
Pid: 27301, comm: oprofiled Not tainted 2.6.26-rc7 #25
[<c028a90d>] debug_smp_processor_id+0xbd/0xc0
[<c045fba1>] nmi_shutdown+0x11/0x60
[<c045dd4a>] oprofile_shutdown+0x2a/0x60

Note that we don't need this for the other functions, since they are all
called with on_each_cpu() (which disables preemption for us anyway).

Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>
---
arch/x86/oprofile/nmi_int.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/arch/x86/oprofile/nmi_int.c b/arch/x86/oprofile/nmi_int.c
index cc48d3f..2b6ad5b 100644
--- a/arch/x86/oprofile/nmi_int.c
+++ b/arch/x86/oprofile/nmi_int.c
@@ -269,12 +269,13 @@ static void nmi_cpu_shutdown(void *dummy)

static void nmi_shutdown(void)
{
- struct op_msrs *msrs = &__get_cpu_var(cpu_msrs);
+ struct op_msrs *msrs = &get_cpu_var(cpu_msrs);
nmi_enabled = 0;
on_each_cpu(nmi_cpu_shutdown, NULL, 0, 1);
unregister_die_notifier(&profile_exceptions_nb);
model->shutdown(msrs);
free_msrs();
+ put_cpu_var(cpu_msrs);
}

static void nmi_cpu_start(void *dummy)
--
1.5.4.1


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