* [PATCH] powerpc/pseries: avoid harmless preempt warning
@ 2020-03-20 15:24 Nicholas Piggin
2020-03-20 15:33 ` Christophe Leroy
2020-03-26 12:06 ` Michael Ellerman
0 siblings, 2 replies; 4+ messages in thread
From: Nicholas Piggin @ 2020-03-20 15:24 UTC (permalink / raw)
To: linuxppc-dev; +Cc: Nicholas Piggin
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/platforms/pseries/lpar.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
index 3c3da25b445c..e4ed5317f117 100644
--- a/arch/powerpc/platforms/pseries/lpar.c
+++ b/arch/powerpc/platforms/pseries/lpar.c
@@ -636,8 +636,16 @@ static const struct proc_ops vcpudispatch_stats_freq_proc_ops = {
static int __init vcpudispatch_stats_procfs_init(void)
{
- if (!lppaca_shared_proc(get_lppaca()))
+ /*
+ * Avoid smp_processor_id while preemptible. All CPUs should have
+ * the same value for lppaca_shared_proc.
+ */
+ preempt_disable();
+ if (!lppaca_shared_proc(get_lppaca())) {
+ preempt_enable();
return 0;
+ }
+ preempt_enable();
if (!proc_create("powerpc/vcpudispatch_stats", 0600, NULL,
&vcpudispatch_stats_proc_ops))
--
2.23.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] powerpc/pseries: avoid harmless preempt warning
2020-03-20 15:24 [PATCH] powerpc/pseries: avoid harmless preempt warning Nicholas Piggin
@ 2020-03-20 15:33 ` Christophe Leroy
2020-03-21 6:34 ` Nicholas Piggin
2020-03-26 12:06 ` Michael Ellerman
1 sibling, 1 reply; 4+ messages in thread
From: Christophe Leroy @ 2020-03-20 15:33 UTC (permalink / raw)
To: Nicholas Piggin, linuxppc-dev
Le 20/03/2020 à 16:24, Nicholas Piggin a écrit :
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> ---
> arch/powerpc/platforms/pseries/lpar.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
> index 3c3da25b445c..e4ed5317f117 100644
> --- a/arch/powerpc/platforms/pseries/lpar.c
> +++ b/arch/powerpc/platforms/pseries/lpar.c
> @@ -636,8 +636,16 @@ static const struct proc_ops vcpudispatch_stats_freq_proc_ops = {
>
> static int __init vcpudispatch_stats_procfs_init(void)
> {
> - if (!lppaca_shared_proc(get_lppaca()))
> + /*
> + * Avoid smp_processor_id while preemptible. All CPUs should have
> + * the same value for lppaca_shared_proc.
> + */
> + preempt_disable();
> + if (!lppaca_shared_proc(get_lppaca())) {
> + preempt_enable();
> return 0;
> + }
> + preempt_enable();
Can we avoid the double preempt_enable() with something like:
preempt_disable();
is_shared = lppaca_shared_proc(get_lppaca());
preempt_enable();
if (!is_shared)
return 0;
>
> if (!proc_create("powerpc/vcpudispatch_stats", 0600, NULL,
> &vcpudispatch_stats_proc_ops))
>
Christophe
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] powerpc/pseries: avoid harmless preempt warning
2020-03-20 15:33 ` Christophe Leroy
@ 2020-03-21 6:34 ` Nicholas Piggin
0 siblings, 0 replies; 4+ messages in thread
From: Nicholas Piggin @ 2020-03-21 6:34 UTC (permalink / raw)
To: Christophe Leroy, linuxppc-dev
Christophe Leroy's on March 21, 2020 1:33 am:
>
>
> Le 20/03/2020 à 16:24, Nicholas Piggin a écrit :
>> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
>> ---
>> arch/powerpc/platforms/pseries/lpar.c | 10 +++++++++-
>> 1 file changed, 9 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
>> index 3c3da25b445c..e4ed5317f117 100644
>> --- a/arch/powerpc/platforms/pseries/lpar.c
>> +++ b/arch/powerpc/platforms/pseries/lpar.c
>> @@ -636,8 +636,16 @@ static const struct proc_ops vcpudispatch_stats_freq_proc_ops = {
>>
>> static int __init vcpudispatch_stats_procfs_init(void)
>> {
>> - if (!lppaca_shared_proc(get_lppaca()))
>> + /*
>> + * Avoid smp_processor_id while preemptible. All CPUs should have
>> + * the same value for lppaca_shared_proc.
>> + */
>> + preempt_disable();
>> + if (!lppaca_shared_proc(get_lppaca())) {
>> + preempt_enable();
>> return 0;
>> + }
>> + preempt_enable();
>
> Can we avoid the double preempt_enable() with something like:
>
> preempt_disable();
> is_shared = lppaca_shared_proc(get_lppaca());
> preempt_enable();
> if (!is_shared)
> return 0;
I don't mind too much. Same number of lines.
Thanks,
Nick
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] powerpc/pseries: avoid harmless preempt warning
2020-03-20 15:24 [PATCH] powerpc/pseries: avoid harmless preempt warning Nicholas Piggin
2020-03-20 15:33 ` Christophe Leroy
@ 2020-03-26 12:06 ` Michael Ellerman
1 sibling, 0 replies; 4+ messages in thread
From: Michael Ellerman @ 2020-03-26 12:06 UTC (permalink / raw)
To: Nicholas Piggin, linuxppc-dev; +Cc: Nicholas Piggin
On Fri, 2020-03-20 at 15:24:36 UTC, Nicholas Piggin wrote:
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Applied to powerpc next, thanks.
https://git.kernel.org/powerpc/c/adde8715cf0571878d37fcb20595aad57b923bab
cheers
^ permalink raw reply [flat|nested] 4+ messages in thread
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2020-03-20 15:33 ` Christophe Leroy
2020-03-21 6:34 ` Nicholas Piggin
2020-03-26 12:06 ` Michael Ellerman
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