lkml.org 
[lkml]   [2010]   [Oct]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH 6/7] tracing: Use one prologue for the preempt irqs off tracer function tracers
From: Steven Rostedt <srostedt@redhat.com>

The preempt and irqsoff tracers have three types of function tracers.
Normal function tracer, function graph entry, and function graph return.
Each of these use a complex dance to prevent recursion and whether
to trace the data or not (depending if interrupts are enabled or not).

This patch moves the duplicate code into a single routine, to
prevent future mistakes with modifying duplicate complex code.

Cc: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/trace_irqsoff.c | 96 +++++++++++++++++++++---------------------
1 files changed, 48 insertions(+), 48 deletions(-)
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index 4047e98..5cf8c60 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -87,14 +87,22 @@ static __cacheline_aligned_in_smp unsigned long max_sequence;

#ifdef CONFIG_FUNCTION_TRACER
/*
- * irqsoff uses its own tracer function to keep the overhead down:
+ * Prologue for the preempt and irqs off function tracers.
+ *
+ * Returns 1 if it is OK to continue, and data->disabled is
+ * incremented.
+ * 0 if the trace is to be ignored, and data->disabled
+ * is kept the same.
+ *
+ * Note, this function is also used outside this ifdef but
+ * inside the #ifdef of the function graph tracer below.
+ * This is OK, since the function graph tracer is
+ * dependent on the function tracer.
*/
-static void
-irqsoff_tracer_call(unsigned long ip, unsigned long parent_ip)
+static int func_prolog_dec(struct trace_array *tr,
+ struct trace_array_cpu **data,
+ unsigned long *flags)
{
- struct trace_array *tr = irqsoff_trace;
- struct trace_array_cpu *data;
- unsigned long flags;
long disabled;
int cpu;

@@ -106,18 +114,38 @@ irqsoff_tracer_call(unsigned long ip, unsigned long parent_ip)
*/
cpu = raw_smp_processor_id();
if (likely(!per_cpu(tracing_cpu, cpu)))
- return;
+ return 0;

- local_save_flags(flags);
+ local_save_flags(*flags);
/* slight chance to get a false positive on tracing_cpu */
- if (!irqs_disabled_flags(flags))
- return;
+ if (!irqs_disabled_flags(*flags))
+ return 0;

- data = tr->data[cpu];
- disabled = atomic_inc_return(&data->disabled);
+ *data = tr->data[cpu];
+ disabled = atomic_inc_return(&(*data)->disabled);

if (likely(disabled == 1))
- trace_function(tr, ip, parent_ip, flags, preempt_count());
+ return 1;
+
+ atomic_dec(&(*data)->disabled);
+
+ return 0;
+}
+
+/*
+ * irqsoff uses its own tracer function to keep the overhead down:
+ */
+static void
+irqsoff_tracer_call(unsigned long ip, unsigned long parent_ip)
+{
+ struct trace_array *tr = irqsoff_trace;
+ struct trace_array_cpu *data;
+ unsigned long flags;
+
+ if (!func_prolog_dec(tr, &data, &flags))
+ return;
+
+ trace_function(tr, ip, parent_ip, flags, preempt_count());

atomic_dec(&data->disabled);
}
@@ -155,30 +183,16 @@ static int irqsoff_graph_entry(struct ftrace_graph_ent *trace)
struct trace_array *tr = irqsoff_trace;
struct trace_array_cpu *data;
unsigned long flags;
- long disabled;
int ret;
- int cpu;
int pc;

- cpu = raw_smp_processor_id();
- if (likely(!per_cpu(tracing_cpu, cpu)))
- return 0;
-
- local_save_flags(flags);
- /* slight chance to get a false positive on tracing_cpu */
- if (!irqs_disabled_flags(flags))
+ if (!func_prolog_dec(tr, &data, &flags))
return 0;

- data = tr->data[cpu];
- disabled = atomic_inc_return(&data->disabled);
-
- if (likely(disabled == 1)) {
- pc = preempt_count();
- ret = __trace_graph_entry(tr, trace, flags, pc);
- } else
- ret = 0;
-
+ pc = preempt_count();
+ ret = __trace_graph_entry(tr, trace, flags, pc);
atomic_dec(&data->disabled);
+
return ret;
}

@@ -187,27 +201,13 @@ static void irqsoff_graph_return(struct ftrace_graph_ret *trace)
struct trace_array *tr = irqsoff_trace;
struct trace_array_cpu *data;
unsigned long flags;
- long disabled;
- int cpu;
int pc;

- cpu = raw_smp_processor_id();
- if (likely(!per_cpu(tracing_cpu, cpu)))
- return;
-
- local_save_flags(flags);
- /* slight chance to get a false positive on tracing_cpu */
- if (!irqs_disabled_flags(flags))
+ if (!func_prolog_dec(tr, &data, &flags))
return;

- data = tr->data[cpu];
- disabled = atomic_inc_return(&data->disabled);
-
- if (likely(disabled == 1)) {
- pc = preempt_count();
- __trace_graph_return(tr, trace, flags, pc);
- }
-
+ pc = preempt_count();
+ __trace_graph_return(tr, trace, flags, pc);
atomic_dec(&data->disabled);
}

--
1.7.1



\
 
 \ /
  Last update: 2010-10-18 22:35    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site