2020-08-13 12:58:03

by Tianxianting

Subject: [PATCH] tracing: use __this_cpu_read() in trace_buffered_event_enable()

The code is executed with preemption disabled, so it's
safe to use __this_cpu_read().

Signed-off-by: Xianting Tian <[email protected]>
---
kernel/trace/trace.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index bb6226972..7d0d71ce9 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2514,7 +2514,7 @@ void trace_buffered_event_enable(void)

preempt_disable();
if (cpu == smp_processor_id() &&
- this_cpu_read(trace_buffered_event) !=
+ __this_cpu_read(trace_buffered_event) !=
per_cpu(trace_buffered_event, cpu))
WARN_ON_ONCE(1);
preempt_enable();
--
2.17.1

2020-09-18 00:33:38

by Steven Rostedt

Subject: Re: [PATCH] tracing: use __this_cpu_read() in trace_buffered_event_enable()

Sorry for the late reply (been busy with Linux Plumbers, took a
vacation, and then trying to catch up on all my email for the last two
months!)

But I just wanted to let you know that I added this to my queue.

Thanks!

-- Steve


On Thu, 13 Aug 2020 19:28:03 +0800
Xianting Tian <[email protected]> wrote:

> The code is executed with preemption disabled, so it's
> safe to use __this_cpu_read().
>
> Signed-off-by: Xianting Tian <[email protected]>
> ---
> kernel/trace/trace.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index bb6226972..7d0d71ce9 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -2514,7 +2514,7 @@ void trace_buffered_event_enable(void)
>
> preempt_disable();
> if (cpu == smp_processor_id() &&
> - this_cpu_read(trace_buffered_event) !=
> + __this_cpu_read(trace_buffered_event) !=
> per_cpu(trace_buffered_event, cpu))
> WARN_ON_ONCE(1);
> preempt_enable();

2020-09-18 01:23:57

by Tianxianting

Subject: RE: [PATCH] tracing: use __this_cpu_read() in trace_buffered_event_enable()

Hi Steven,
Thanks for your reply:)

-----Original Message-----
From: Steven Rostedt [mailto:[email protected]]
Sent: Friday, September 18, 2020 8:31 AM
To: tianxianting (RD) <[email protected]>
Cc: [email protected]; [email protected]
Subject: Re: [PATCH] tracing: use __this_cpu_read() in trace_buffered_event_enable()

Sorry for the late reply (been busy with Linux Plumbers, took a vacation, and then trying to catch up on all my email for the last two
months!)

But I just wanted to let you know that I added this to my queue.

Thanks!

-- Steve


On Thu, 13 Aug 2020 19:28:03 +0800
Xianting Tian <[email protected]> wrote:

> The code is executed with preemption disabled, so it's safe to use
> __this_cpu_read().
>
> Signed-off-by: Xianting Tian <[email protected]>
> ---
> kernel/trace/trace.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index
> bb6226972..7d0d71ce9 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -2514,7 +2514,7 @@ void trace_buffered_event_enable(void)
>
> preempt_disable();
> if (cpu == smp_processor_id() &&
> - this_cpu_read(trace_buffered_event) !=
> + __this_cpu_read(trace_buffered_event) !=
> per_cpu(trace_buffered_event, cpu))
> WARN_ON_ONCE(1);
> preempt_enable();