tracing: make sched_switch stop/start light weight
The stopping and starting of a tracer should be light weight and
be able to be called in all contexts. The sched_switch grabbed
mutexes in the start/stop functions. This patch changes it to a
simple variable, on/off.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c
index 77132c2..de35f20 100644
--- a/kernel/trace/trace_sched_switch.c
+++ b/kernel/trace/trace_sched_switch.c
@@ -18,6 +18,7 @@
static int __read_mostly tracer_enabled;
static int sched_ref;
static DEFINE_MUTEX(sched_register_mutex);
+static int sched_stopped;
static void
probe_sched_switch(struct rq *__rq, struct task_struct *prev,
@@ -28,7 +29,7 @@
int cpu;
int pc;
- if (!sched_ref)
+ if (!sched_ref || sched_stopped)
return;
tracing_record_cmdline(prev);
@@ -193,6 +194,7 @@
static int sched_switch_trace_init(struct trace_array *tr)
{
ctx_trace = tr;
+ tracing_reset_online_cpus(tr);
tracing_start_sched_switch_record();
return 0;
}
@@ -205,13 +207,12 @@
static void sched_switch_trace_start(struct trace_array *tr)
{
- tracing_reset_online_cpus(tr);
- tracing_start_sched_switch();
+ sched_stopped = 0;
}
static void sched_switch_trace_stop(struct trace_array *tr)
{
- tracing_stop_sched_switch();
+ sched_stopped = 1;
}
static struct tracer sched_switch_trace __read_mostly =