tracing/ftrace: change the type of the init() callback
Impact: extend the ->init() method with the ability to fail
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 <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 80898f4..396fda0 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2638,8 +2638,11 @@
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:
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 790ea8c..cdbd5cc 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -264,7 +264,8 @@
*/
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);
diff --git a/kernel/trace/trace_boot.c b/kernel/trace/trace_boot.c
index cb333b7..a4fa2c5 100644
--- a/kernel/trace/trace_boot.c
+++ b/kernel/trace/trace_boot.c
@@ -47,7 +47,7 @@
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 @@
tracing_reset(tr, cpu);
tracing_sched_switch_assign_trace(tr);
+ return 0;
}
static enum print_line_t
diff --git a/kernel/trace/trace_branch.c b/kernel/trace/trace_branch.c
index 8526555..44bd395 100644
--- a/kernel/trace/trace_branch.c
+++ b/kernel/trace/trace_branch.c
@@ -125,7 +125,7 @@
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 @@
tracing_reset(tr, cpu);
start_branch_trace(tr);
+ return 0;
}
static void branch_trace_reset(struct trace_array *tr)
diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
index 8693b7a..e74f6d0 100644
--- a/kernel/trace/trace_functions.c
+++ b/kernel/trace/trace_functions.c
@@ -42,9 +42,10 @@
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)
diff --git a/kernel/trace/trace_functions_return.c b/kernel/trace/trace_functions_return.c
index 7680b21..61185f7 100644
--- a/kernel/trace/trace_functions_return.c
+++ b/kernel/trace/trace_functions_return.c
@@ -24,13 +24,14 @@
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)
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index d919d4e..7c2e326 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -416,11 +416,12 @@
}
#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 @@
#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 @@
#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 =
diff --git a/kernel/trace/trace_mmiotrace.c b/kernel/trace/trace_mmiotrace.c
index 51bcf37..433d650 100644
--- a/kernel/trace/trace_mmiotrace.c
+++ b/kernel/trace/trace_mmiotrace.c
@@ -30,13 +30,14 @@
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)
diff --git a/kernel/trace/trace_nop.c b/kernel/trace/trace_nop.c
index 2ef1d22..0e77415 100644
--- a/kernel/trace/trace_nop.c
+++ b/kernel/trace/trace_nop.c
@@ -24,7 +24,7 @@
/* 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 @@
tracing_reset(tr, cpu);
start_nop_trace(tr);
+ return 0;
}
static void nop_trace_reset(struct trace_array *tr)
diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c
index be35bdf..8633905 100644
--- a/kernel/trace/trace_sched_switch.c
+++ b/kernel/trace/trace_sched_switch.c
@@ -206,10 +206,11 @@
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)
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index 983f2b1..0067b49 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -331,10 +331,11 @@
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)
diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
index 5cb64ea..88c8eb7 100644
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -71,6 +71,11 @@
return ret;
}
+static inline void warn_failed_init_tracer(struct tracer *trace, int init_ret)
+{
+ printk(KERN_WARNING "Failed to init %s tracer, init returned %d\n",
+ trace->name, init_ret);
+}
#ifdef CONFIG_FUNCTION_TRACER
#ifdef CONFIG_DYNAMIC_FTRACE
@@ -111,7 +116,11 @@
ftrace_set_filter(func_name, strlen(func_name), 1);
/* enable tracing */
- trace->init(tr);
+ ret = trace->init(tr);
+ if (ret) {
+ warn_failed_init_tracer(trace, ret);
+ goto out;
+ }
/* Sleep for a 1/10 of a second */
msleep(100);
@@ -181,7 +190,12 @@
ftrace_enabled = 1;
tracer_enabled = 1;
- trace->init(tr);
+ ret = trace->init(tr);
+ if (ret) {
+ warn_failed_init_tracer(trace, ret);
+ goto out;
+ }
+
/* Sleep for a 1/10 of a second */
msleep(100);
/* stop the tracing. */
@@ -223,7 +237,12 @@
int ret;
/* start the tracing */
- trace->init(tr);
+ ret = trace->init(tr);
+ if (ret) {
+ warn_failed_init_tracer(trace, ret);
+ return ret;
+ }
+
/* reset the max latency */
tracing_max_latency = 0;
/* disable interrupts for a bit */
@@ -272,7 +291,12 @@
}
/* start the tracing */
- trace->init(tr);
+ ret = trace->init(tr);
+ if (ret) {
+ warn_failed_init_tracer(trace, ret);
+ return ret;
+ }
+
/* reset the max latency */
tracing_max_latency = 0;
/* disable preemption for a bit */
@@ -321,7 +345,11 @@
}
/* start the tracing */
- trace->init(tr);
+ ret = trace->init(tr);
+ if (ret) {
+ warn_failed_init_tracer(trace, ret);
+ goto out;
+ }
/* reset the max latency */
tracing_max_latency = 0;
@@ -449,7 +477,12 @@
wait_for_completion(&isrt);
/* start the tracing */
- trace->init(tr);
+ ret = trace->init(tr);
+ if (ret) {
+ warn_failed_init_tracer(trace, ret);
+ return ret;
+ }
+
/* reset the max latency */
tracing_max_latency = 0;
@@ -505,7 +538,12 @@
int ret;
/* start the tracing */
- trace->init(tr);
+ ret = trace->init(tr);
+ if (ret) {
+ warn_failed_init_tracer(trace, ret);
+ return ret;
+ }
+
/* Sleep for a 1/10 of a second */
msleep(100);
/* stop the tracing. */
@@ -532,7 +570,12 @@
int ret;
/* start the tracing */
- trace->init(tr);
+ ret = trace->init(tr);
+ if (ret) {
+ warn_failed_init_tracer(trace, ret);
+ return 0;
+ }
+
/* Sleep for a 1/10 of a second */
msleep(100);
/* stop the tracing. */
@@ -554,7 +597,12 @@
int ret;
/* start the tracing */
- trace->init(tr);
+ ret = trace->init(tr);
+ if (ret) {
+ warn_failed_init_tracer(trace, ret);
+ return ret;
+ }
+
/* Sleep for a 1/10 of a second */
msleep(100);
/* stop the tracing. */
diff --git a/kernel/trace/trace_sysprof.c b/kernel/trace/trace_sysprof.c
index 05f7534..54960ed 100644
--- a/kernel/trace/trace_sysprof.c
+++ b/kernel/trace/trace_sysprof.c
@@ -261,11 +261,12 @@
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)