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tracing: Kill unused and puzzled sample code in ftrace.h

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When doing per-cpu helper optimizing work, find that this code is so puzzled.
1. It's mark as comment text, maybe a sample function for guidelines
   or a todo work.
2. But, this sample code is odd where struct perf_trace_buf is nonexistent.
   commit ce71b9 delete struct perf_trace_buf definition.

   Author: Frederic Weisbecker <fweisbec@gmail.com>
   Date:   Sun Nov 22 05:26:55 2009 +0100

   tracing: Use the perf recursion protection from trace event

Is it necessary to keep there?
just compile test.

Link: http://lkml.kernel.org/r/50949FC9.6050202@gmail.com

Signed-off-by: Shan Wei <davidshan@tencent.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Shan Wei 2012-11-03 12:38:33 +08:00 committed by Steven Rostedt
parent 11043d8b12
commit 1c7d667324
1 changed files with 0 additions and 73 deletions
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73
include/trace/ftrace.h
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@ -619,79 +619,6 @@ __attribute__((section("_ftrace_events"))) *__event_##call = &event_##call
#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
/*
* Define the insertion callback to perf events
*
* The job is very similar to ftrace_raw_event_<call> except that we don't
* insert in the ring buffer but in a perf counter.
*
* static void ftrace_perf_<call>(proto)
* {
* struct ftrace_data_offsets_<call> __maybe_unused __data_offsets;
* struct ftrace_event_call *event_call = &event_<call>;
* extern void perf_tp_event(int, u64, u64, void *, int);
* struct ftrace_raw_##call *entry;
* struct perf_trace_buf *trace_buf;
* u64 __addr = 0, __count = 1;
* unsigned long irq_flags;
* struct trace_entry *ent;
* int __entry_size;
* int __data_size;
* int __cpu
* int pc;
*
* pc = preempt_count();
*
* __data_size = ftrace_get_offsets_<call>(&__data_offsets, args);
*
* // Below we want to get the aligned size by taking into account
* // the u32 field that will later store the buffer size
* __entry_size = ALIGN(__data_size + sizeof(*entry) + sizeof(u32),
* sizeof(u64));
* __entry_size -= sizeof(u32);
*
* // 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);
* else
* trace_buf = rcu_dereference_sched(perf_trace_buf);
*
* if (!trace_buf)
* goto end;
*
* trace_buf = per_cpu_ptr(trace_buf, __cpu);
*
* // Avoid recursion from perf that could mess up the buffer
* if (trace_buf->recursion++)
* goto end_recursion;
*
* raw_data = trace_buf->buf;
*
* // Make recursion update visible before entering perf_tp_event
* // so that we protect from perf recursions.
*
* barrier();
*
* //zero dead bytes from alignment to avoid stack leak to userspace:
* *(u64 *)(&raw_data[__entry_size - sizeof(u64)]) = 0ULL;
* entry = (struct ftrace_raw_<call> *)raw_data;
* ent = &entry->ent;
* tracing_generic_entry_update(ent, irq_flags, pc);
* ent->type = event_call->id;
*
* <tstruct> <- do some jobs with dynamic arrays
*
* <assign> <- affect our values
*
* perf_tp_event(event_call->id, __addr, __count, entry,
* __entry_size); <- submit them to perf counter
*
* }
*/
#ifdef CONFIG_PERF_EVENTS