From: Chunyan Zhang <zhang.chunyan@linaro.org>
To: Will Deacon <will.deacon@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>,
Steven Rostedt <rostedt@goodmis.org>,
linux-arch@vger.kernel.org,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Lyra Zhang <zhang.lyra@gmail.com>
Subject: Re: [PATCH] percpu: make this_cpu_generic_read notrace
Date: Fri, 16 Sep 2016 18:08:24 +0800 [thread overview]
Message-ID: <CAG2=9p-iVgt1e3FyBOg8AkbzeY5Z5=JMHjpayaFPAPhvsFAQKA@mail.gmail.com> (raw)
In-Reply-To: <20160916095309.GM3380@arm.com>
On 16 September 2016 at 17:53, Will Deacon <will.deacon@arm.com> wrote:
> On Fri, Sep 16, 2016 at 04:42:44PM +0800, Chunyan Zhang wrote:
>> Hi Will and Steven,
>>
>> May I have a review or an acked-by from you on this patch so that Arnd
>> can pick it up.
>>
>> I have tested this patch on arm qemu, I'm sure it can solve the
>> problem described in commit message.
>
> It looks fine to me; we took your equivalent patch for arm64 already, so:
Yeah, I saw that.
>
> Acked-by: Will Deacon <will.deacon@arm.com>
Thanks,
Chunyan
>
> Will
>
>> On 10 September 2016 at 16:45, Chunyan Zhang <zhang.chunyan@linaro.org> wrote:
>> > When debug preempt or preempt tracer is enabled, preempt_count_add/sub()
>> > can be traced by function and function graph tracing, and
>> > preempt_disable/enable() would call preempt_count_add/sub(), so
>> > we should use preempt_disable/enable_notrace in Ftrace subsystem.
>> >
>> > The function this_cpu_read() started being used by function graph tracing
>> > after the commit 345ddcc882d8 ("ftrace: Have set_ftrace_pid use the
>> > bitmap like events do"), so it has to use preempt_disable/enable_notrace
>> > instead now.
>> >
>> > Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>
>> > ---
>> > include/asm-generic/percpu.h | 4 ++--
>> > 1 file changed, 2 insertions(+), 2 deletions(-)
>> >
>> > diff --git a/include/asm-generic/percpu.h b/include/asm-generic/percpu.h
>> > index 4d9f233..70fefec 100644
>> > --- a/include/asm-generic/percpu.h
>> > +++ b/include/asm-generic/percpu.h
>> > @@ -108,9 +108,9 @@ do { \
>> > #define this_cpu_generic_read(pcp) \
>> > ({ \
>> > typeof(pcp) __ret; \
>> > - preempt_disable(); \
>> > + preempt_disable_notrace(); \
>> > __ret = *this_cpu_ptr(&(pcp)); \
>> > - preempt_enable(); \
>> > + preempt_enable_notrace(); \
>> > __ret; \
>> > })
>> >
>> > --
>> > 2.7.4
>> >
>>
next prev parent reply other threads:[~2016-09-16 10:08 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-10 8:45 [PATCH] percpu: make this_cpu_generic_read notrace Chunyan Zhang
2016-09-16 8:42 ` Chunyan Zhang
2016-09-16 9:53 ` Will Deacon
2016-09-16 10:08 ` Chunyan Zhang [this message]
2016-09-16 13:19 ` Steven Rostedt
2016-09-24 9:18 ` Arnd Bergmann
2016-09-24 9:18 ` Arnd Bergmann
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