tracing/ftrace: Change the type of the init() callback

PATCH Applied Frederic Weisbecker 2 participants 2 messages Nov 16, 2008

Subsystems (3)

Tracing Tracing OS noise / latency tracers Tracing MMIO accesses (mmiotrace)

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Frederic Weisbecker

author

2008-11-16 04:57 UTC #0 lore raw

PATCH 2/4 tracing/ftrace: Change the type of the init() callback

Impact: Handle errors during initialization of a tracer

This bring a way to know if the initialization of a tracer successed. A tracer must return 0 on success and a traditional error (ie: -ENOMEM) if it fails.
If a tracer fails to init, it is free to print a detailed warn. The tracing api will not and switch to a new tracer will just return the error from the init callback.

Note: this will be used for the return tracer.

Signed-off-by Frederic Weisbecker <[email protected]>

Cc Steven Rostedt <[email protected]>

Cc Pekka Paalanen <[email protected]>

Cc Steven Noonan <[email protected]>

---
 kernel/trace/trace.c                  |    7 ++-
 kernel/trace/trace.h                  |    3 +-
 kernel/trace/trace_boot.c             |    3 +-
 kernel/trace/trace_branch.c           |    3 +-
 kernel/trace/trace_functions.c        |    3 +-
 kernel/trace/trace_functions_return.c |    3 +-
 kernel/trace/trace_irqsoff.c          |    9 +++-
 kernel/trace/trace_mmiotrace.c        |    3 +-
 kernel/trace/trace_nop.c              |    3 +-
 kernel/trace/trace_sched_switch.c     |    3 +-
 kernel/trace/trace_sched_wakeup.c     |    3 +-
 kernel/trace/trace_selftest.c         |   66 ++++++++++++++++++++++++++++----
 kernel/trace/trace_sysprof.c          |    3 +-
 13 files changed, 88 insertions(+), 24 deletions(-)

kernel/trace/trace.c +5 -2

index 2d5672d..938ee31 100644
@@ -2638,8 +2638,11 @@ static int tracing_set_tracer(char *buf)
 		current_trace->reset(tr);
 
 	current_trace = t;
-	if (t->init)
-		t->init(tr);
+	if (t->init) {
+		ret = t->init(tr);
+		if (ret)
+			goto out;
+	}
 
 	trace_branch_enable(tr);
  out:

kernel/trace/trace.h +2 -1

index 790ea8c..cdbd5cc 100644
@@ -264,7 +264,8 @@ enum print_line_t {
  */
 struct tracer {
 	const char		*name;
-	void			(*init)(struct trace_array *tr);
+	/* Your tracer should raise a warning if init fails */
+	int			(*init)(struct trace_array *tr);
 	void			(*reset)(struct trace_array *tr);
 	void			(*start)(struct trace_array *tr);
 	void			(*stop)(struct trace_array *tr);

kernel/trace/trace_boot.c +2 -1

index cb333b7..a4fa2c5 100644
@@ -47,7 +47,7 @@ static void reset_boot_trace(struct trace_array *tr)
 		tracing_reset(tr, cpu);
 }
 
-static void boot_trace_init(struct trace_array *tr)
+static int boot_trace_init(struct trace_array *tr)
 {
 	int cpu;
 	boot_trace = tr;

@@ -56,6 +56,7 @@ static void boot_trace_init(struct trace_array *tr)
 		tracing_reset(tr, cpu);
 
 	tracing_sched_switch_assign_trace(tr);
+	return 0;
 }
 
 static enum print_line_t

kernel/trace/trace_branch.c +2 -1

index 8526555..44bd395 100644
@@ -125,7 +125,7 @@ static void stop_branch_trace(struct trace_array *tr)
 	disable_branch_tracing();
 }
 
-static void branch_trace_init(struct trace_array *tr)
+static int branch_trace_init(struct trace_array *tr)
 {
 	int cpu;

@@ -133,6 +133,7 @@ static void branch_trace_init(struct trace_array *tr)
 		tracing_reset(tr, cpu);
 
 	start_branch_trace(tr);
+	return 0;
 }
 
 static void branch_trace_reset(struct trace_array *tr)

kernel/trace/trace_functions.c +2 -1

index 8693b7a..e74f6d0 100644
@@ -42,9 +42,10 @@ static void stop_function_trace(struct trace_array *tr)
 	tracing_stop_cmdline_record();
 }
 
-static void function_trace_init(struct trace_array *tr)
+static int function_trace_init(struct trace_array *tr)
 {
 	start_function_trace(tr);
+	return 0;
 }
 
 static void function_trace_reset(struct trace_array *tr)

kernel/trace/trace_functions_return.c +2 -1

index 7680b21..61185f7 100644
@@ -24,13 +24,14 @@ static void stop_return_trace(struct trace_array *tr)
 	unregister_ftrace_return();
 }
 
-static void return_trace_init(struct trace_array *tr)
+static int return_trace_init(struct trace_array *tr)
 {
 	int cpu;
 	for_each_online_cpu(cpu)
 		tracing_reset(tr, cpu);
 
 	start_return_trace(tr);
+	return 0;
 }
 
 static void return_trace_reset(struct trace_array *tr)

kernel/trace/trace_irqsoff.c +6 -3

index d919d4e..7c2e326 100644
@@ -416,11 +416,12 @@ static void irqsoff_tracer_close(struct trace_iterator *iter)
 }
 
 #ifdef CONFIG_IRQSOFF_TRACER
-static void irqsoff_tracer_init(struct trace_array *tr)
+static int irqsoff_tracer_init(struct trace_array *tr)
 {
 	trace_type = TRACER_IRQS_OFF;
 
 	__irqsoff_tracer_init(tr);
+	return 0;
 }
 static struct tracer irqsoff_tracer __read_mostly =
 {

@@ -442,11 +443,12 @@ static struct tracer irqsoff_tracer __read_mostly =
 #endif
 
 #ifdef CONFIG_PREEMPT_TRACER
-static void preemptoff_tracer_init(struct trace_array *tr)
+static int preemptoff_tracer_init(struct trace_array *tr)
 {
 	trace_type = TRACER_PREEMPT_OFF;
 
 	__irqsoff_tracer_init(tr);
+	return 0;
 }
 
 static struct tracer preemptoff_tracer __read_mostly =

@@ -471,11 +473,12 @@ static struct tracer preemptoff_tracer __read_mostly =
 #if defined(CONFIG_IRQSOFF_TRACER) && \
 	defined(CONFIG_PREEMPT_TRACER)
 
-static void preemptirqsoff_tracer_init(struct trace_array *tr)
+static int preemptirqsoff_tracer_init(struct trace_array *tr)
 {
 	trace_type = TRACER_IRQS_OFF | TRACER_PREEMPT_OFF;
 
 	__irqsoff_tracer_init(tr);
+	return 0;
 }
 
 static struct tracer preemptirqsoff_tracer __read_mostly =

kernel/trace/trace_mmiotrace.c +2 -1

index 51bcf37..433d650 100644
@@ -30,13 +30,14 @@ static void mmio_reset_data(struct trace_array *tr)
 		tracing_reset(tr, cpu);
 }
 
-static void mmio_trace_init(struct trace_array *tr)
+static int mmio_trace_init(struct trace_array *tr)
 {
 	pr_debug("in %s\n", __func__);
 	mmio_trace_array = tr;
 
 	mmio_reset_data(tr);
 	enable_mmiotrace();
+	return 0;
 }
 
 static void mmio_trace_reset(struct trace_array *tr)

kernel/trace/trace_nop.c +2 -1

index 2ef1d22..0e77415 100644
@@ -24,7 +24,7 @@ static void stop_nop_trace(struct trace_array *tr)
 	/* Nothing to do! */
 }
 
-static void nop_trace_init(struct trace_array *tr)
+static int nop_trace_init(struct trace_array *tr)
 {
 	int cpu;
 	ctx_trace = tr;

@@ -33,6 +33,7 @@ static void nop_trace_init(struct trace_array *tr)
 		tracing_reset(tr, cpu);
 
 	start_nop_trace(tr);
+	return 0;
 }
 
 static void nop_trace_reset(struct trace_array *tr)

kernel/trace/trace_sched_switch.c +2 -1

index be35bdf..8633905 100644
@@ -206,10 +206,11 @@ static void stop_sched_trace(struct trace_array *tr)
 	tracing_stop_sched_switch_record();
 }
 
-static void sched_switch_trace_init(struct trace_array *tr)
+static int sched_switch_trace_init(struct trace_array *tr)
 {
 	ctx_trace = tr;
 	start_sched_trace(tr);
+	return 0;
 }
 
 static void sched_switch_trace_reset(struct trace_array *tr)

kernel/trace/trace_sched_wakeup.c +2 -1

index 983f2b1..0067b49 100644
@@ -331,10 +331,11 @@ static void stop_wakeup_tracer(struct trace_array *tr)
 	unregister_trace_sched_wakeup(probe_wakeup);
 }
 
-static void wakeup_tracer_init(struct trace_array *tr)
+static int wakeup_tracer_init(struct trace_array *tr)
 {
 	wakeup_trace = tr;
 	start_wakeup_tracer(tr);
+	return 0;
 }
 
 static void wakeup_tracer_reset(struct trace_array *tr)

kernel/trace/trace_selftest.c +57 -9

126 lines not on this page · raw message

kernel/trace/trace_sysprof.c +2 -1

index dc2f690..a10a8dc 100644
@@ -261,11 +261,12 @@ static void stop_stack_trace(struct trace_array *tr)
 	mutex_unlock(&sample_timer_lock);
 }
 
-static void stack_trace_init(struct trace_array *tr)
+static int stack_trace_init(struct trace_array *tr)
 {
 	sysprof_trace = tr;
 
 	start_stack_trace(tr);
+	return 0;
 }
 
 static void stack_trace_reset(struct trace_array *tr)

Signature · 1 line

1.5.2.5

Pekka Paalanen

2008-11-16 22:40 UTC #1 lore raw

Quoted 63 lines · On Sun, 16 Nov 2008 05:57:26 +0100 Frederic Weisbecker <[email protected]>…

Impact: Handle errors during initialization of a tracer

Note: this will be used for the return tracer.

Signed-off-by Frederic Weisbecker <[email protected]>

Cc Steven Rostedt <[email protected]>

Cc Pekka Paalanen <[email protected]>

Cc Steven Noonan <[email protected]>

---
 kernel/trace/trace.c                  |    7 ++-
 kernel/trace/trace.h                  |    3 +-
 kernel/trace/trace_boot.c             |    3 +-
 kernel/trace/trace_branch.c           |    3 +-
 kernel/trace/trace_functions.c        |    3 +-
 kernel/trace/trace_functions_return.c |    3 +-
 kernel/trace/trace_irqsoff.c          |    9 +++-
 kernel/trace/trace_mmiotrace.c        |    3 +-
 kernel/trace/trace_nop.c              |    3 +-
 kernel/trace/trace_sched_switch.c     |    3 +-
 kernel/trace/trace_sched_wakeup.c     |    3 +-
 kernel/trace/trace_selftest.c         |   66 ++++++++++++++++++++++++++++----
 kernel/trace/trace_sysprof.c          |    3 +-
 13 files changed, 88 insertions(+), 24 deletions(-)

kernel/trace/trace.c +5 -2

index 2d5672d..938ee31 100644
@@ -2638,8 +2638,11 @@ static int tracing_set_tracer(char *buf)
 		current_trace->reset(tr);
 
 	current_trace = t;
-	if (t->init)
-		t->init(tr);
+	if (t->init) {
+		ret = t->init(tr);
+		if (ret)
+			goto out;
+	}
 
 	trace_branch_enable(tr);
  out:

kernel/trace/trace.h +2 -1

index 790ea8c..cdbd5cc 100644
@@ -264,7 +264,8 @@ enum print_line_t {
  */
 struct tracer {
 	const char		*name;
-	void			(*init)(struct trace_array *tr);
+	/* Your tracer should raise a warning if init fails */
+	int			(*init)(struct trace_array *tr);
 	void			(*reset)(struct trace_array *tr);
 	void			(*start)(struct trace_array *tr);
 	void			(*stop)(struct trace_array *tr);

...

Quoted 10 lines

kernel/trace/trace_mmiotrace.c +1 -1

index 51bcf37..433d650 100644
@@ -30,13 +30,14 @@ static void mmio_reset_data(struct trace_array *tr)
 		tracing_reset(tr, cpu);
 }
 
-static void mmio_trace_init(struct trace_array *tr)
+static int mmio_trace_init(struct trace_array *tr)

kernel/trace/trace_mmiotrace.c static void mmio_reset_data(struct trace_array *tr) · line 43

Quoted 10 lines

kernel/trace/trace_mmiotrace.c +1 -0

 {
 	pr_debug("in %s\n", __func__);
 	mmio_trace_array = tr;
 
 	mmio_reset_data(tr);
 	enable_mmiotrace();
+	return 0;
 }
 
 static void mmio_trace_reset(struct trace_array *tr)

On a quick glance, I didn't see anything wrong in these parts. I leave it for later to check if enable_mmiotrace() could fail and if it should be propagated.

Thanks.

Signature · 2 lines

Pekka Paalanen
http://www.iki.fi/pq/