2012-10-31 11:23:03

by Shan Wei

Subject: [PATCH 5/9] ftrace: use this_cpu_ptr per-cpu helper

From: Shan Wei <[email protected]>

Signed-off-by: Shan Wei <[email protected]>
---
include/trace/ftrace.h | 4 +---
1 files changed, 1 insertions(+), 3 deletions(-)

diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index a763888..7c9fde7 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -638,7 +638,6 @@ __attribute__((section("_ftrace_events"))) *__event_##call = &event_##call
* struct trace_entry *ent;
* int __entry_size;
* int __data_size;
- * int __cpu
* int pc;
*
* pc = preempt_count();
@@ -654,7 +653,6 @@ __attribute__((section("_ftrace_events"))) *__event_##call = &event_##call
* // Protect the non nmi buffer
* // This also protects the rcu read side
* local_irq_save(irq_flags);
- * __cpu = smp_processor_id();
*
* if (in_nmi())
* trace_buf = rcu_dereference_sched(perf_trace_buf_nmi);
@@ -664,7 +662,7 @@ __attribute__((section("_ftrace_events"))) *__event_##call = &event_##call
* if (!trace_buf)
* goto end;
*
- * trace_buf = per_cpu_ptr(trace_buf, __cpu);
+ * trace_buf = this_cpu_ptr(trace_buf);
*
* // Avoid recursion from perf that could mess up the buffer
* if (trace_buf->recursion++)
--
1.7.1

2012-10-31 17:43:30

by Christoph Lameter (Ampere)

Subject: Re: [PATCH 5/9] ftrace: use this_cpu_ptr per-cpu helper

On Wed, 31 Oct 2012, Shan Wei wrote:

> diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
> index a763888..7c9fde7 100644
> --- a/include/trace/ftrace.h
> +++ b/include/trace/ftrace.h
> @@ -638,7 +638,6 @@ __attribute__((section("_ftrace_events"))) *__event_##call = &event_##call
> * struct trace_entry *ent;
> * int __entry_size;
> * int __data_size;
> - * int __cpu
> * int pc;
> *
> * pc = preempt_count();
> @@ -654,7 +653,6 @@ __attribute__((section("_ftrace_events"))) *__event_##call = &event_##call
> * // Protect the non nmi buffer
> * // This also protects the rcu read side
> * local_irq_save(irq_flags);
> - * __cpu = smp_processor_id();
> *
> * if (in_nmi())
> * trace_buf = rcu_dereference_sched(perf_trace_buf_nmi);
> @@ -664,7 +662,7 @@ __attribute__((section("_ftrace_events"))) *__event_##call = &event_##call
> * if (!trace_buf)
> * goto end;
> *
> - * trace_buf = per_cpu_ptr(trace_buf, __cpu);
> + * trace_buf = this_cpu_ptr(trace_buf);
> *
> * // Avoid recursion from perf that could mess up the buffer
> * if (trace_buf->recursion++)

Reviewed-by: Christoph Lameter <[email protected]>

Code could be further reduced by not doing the this_cpu_ptr op but using
this_cpu_read later instead.