tracing: Remove ftrace_disable/enable_cpu()
The ftrace_disable_cpu() and ftrace_enable_cpu() functions were
needed back before the ring buffer was lockless. Now that the
ring buffer is lockless (and has been for some time), these functions
serve no purpose, and unnecessarily slow down operations of the tracer.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 4fb10ef..48ef496 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -87,18 +87,6 @@
DEFINE_PER_CPU(int, ftrace_cpu_disabled);
-static inline void ftrace_disable_cpu(void)
-{
- preempt_disable();
- __this_cpu_inc(ftrace_cpu_disabled);
-}
-
-static inline void ftrace_enable_cpu(void)
-{
- __this_cpu_dec(ftrace_cpu_disabled);
- preempt_enable();
-}
-
cpumask_var_t __read_mostly tracing_buffer_mask;
/*
@@ -748,8 +736,6 @@
arch_spin_lock(&ftrace_max_lock);
- ftrace_disable_cpu();
-
ret = ring_buffer_swap_cpu(max_tr.buffer, tr->buffer, cpu);
if (ret == -EBUSY) {
@@ -763,8 +749,6 @@
"Failed to swap buffers due to commit in progress\n");
}
- ftrace_enable_cpu();
-
WARN_ON_ONCE(ret && ret != -EAGAIN && ret != -EBUSY);
__update_max_tr(tr, tsk, cpu);
@@ -916,13 +900,6 @@
mutex_unlock(&trace_types_lock);
}
-static void __tracing_reset(struct ring_buffer *buffer, int cpu)
-{
- ftrace_disable_cpu();
- ring_buffer_reset_cpu(buffer, cpu);
- ftrace_enable_cpu();
-}
-
void tracing_reset(struct trace_array *tr, int cpu)
{
struct ring_buffer *buffer = tr->buffer;
@@ -931,7 +908,7 @@
/* Make sure all commits have finished */
synchronize_sched();
- __tracing_reset(buffer, cpu);
+ ring_buffer_reset_cpu(buffer, cpu);
ring_buffer_record_enable(buffer);
}
@@ -949,7 +926,7 @@
tr->time_start = ftrace_now(tr->cpu);
for_each_online_cpu(cpu)
- __tracing_reset(buffer, cpu);
+ ring_buffer_reset_cpu(buffer, cpu);
ring_buffer_record_enable(buffer);
}
@@ -1733,14 +1710,9 @@
static void trace_iterator_increment(struct trace_iterator *iter)
{
- /* Don't allow ftrace to trace into the ring buffers */
- ftrace_disable_cpu();
-
iter->idx++;
if (iter->buffer_iter[iter->cpu])
ring_buffer_read(iter->buffer_iter[iter->cpu], NULL);
-
- ftrace_enable_cpu();
}
static struct trace_entry *
@@ -1750,17 +1722,12 @@
struct ring_buffer_event *event;
struct ring_buffer_iter *buf_iter = iter->buffer_iter[cpu];
- /* Don't allow ftrace to trace into the ring buffers */
- ftrace_disable_cpu();
-
if (buf_iter)
event = ring_buffer_iter_peek(buf_iter, ts);
else
event = ring_buffer_peek(iter->tr->buffer, cpu, ts,
lost_events);
- ftrace_enable_cpu();
-
if (event) {
iter->ent_size = ring_buffer_event_length(event);
return ring_buffer_event_data(event);
@@ -1850,11 +1817,8 @@
static void trace_consume(struct trace_iterator *iter)
{
- /* Don't allow ftrace to trace into the ring buffers */
- ftrace_disable_cpu();
ring_buffer_consume(iter->tr->buffer, iter->cpu, &iter->ts,
&iter->lost_events);
- ftrace_enable_cpu();
}
static void *s_next(struct seq_file *m, void *v, loff_t *pos)
@@ -1943,16 +1907,12 @@
iter->cpu = 0;
iter->idx = -1;
- ftrace_disable_cpu();
-
if (cpu_file == TRACE_PIPE_ALL_CPU) {
for_each_tracing_cpu(cpu)
tracing_iter_reset(iter, cpu);
} else
tracing_iter_reset(iter, cpu_file);
- ftrace_enable_cpu();
-
iter->leftover = 0;
for (p = iter; p && l < *pos; p = s_next(m, p, &l))
;
