summaryrefslogtreecommitdiffstats
path: root/kernel/trace/trace.c
diff options
context:
space:
mode:
Diffstat (limited to 'kernel/trace/trace.c')
-rw-r--r--kernel/trace/trace.c113
1 files changed, 113 insertions, 0 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 10d5503f0d04..ed7b5d1e12f4 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -36,6 +36,7 @@
#include <linux/ctype.h>
#include <linux/init.h>
#include <linux/poll.h>
+#include <linux/nmi.h>
#include <linux/fs.h>
#include "trace.h"
@@ -352,6 +353,59 @@ static void wakeup_work_handler(struct work_struct *work)
static DECLARE_DELAYED_WORK(wakeup_work, wakeup_work_handler);
/**
+ * tracing_on - enable tracing buffers
+ *
+ * This function enables tracing buffers that may have been
+ * disabled with tracing_off.
+ */
+void tracing_on(void)
+{
+ if (global_trace.buffer)
+ ring_buffer_record_on(global_trace.buffer);
+ /*
+ * This flag is only looked at when buffers haven't been
+ * allocated yet. We don't really care about the race
+ * between setting this flag and actually turning
+ * on the buffer.
+ */
+ global_trace.buffer_disabled = 0;
+}
+EXPORT_SYMBOL_GPL(tracing_on);
+
+/**
+ * tracing_off - turn off tracing buffers
+ *
+ * This function stops the tracing buffers from recording data.
+ * It does not disable any overhead the tracers themselves may
+ * be causing. This function simply causes all recording to
+ * the ring buffers to fail.
+ */
+void tracing_off(void)
+{
+ if (global_trace.buffer)
+ ring_buffer_record_on(global_trace.buffer);
+ /*
+ * This flag is only looked at when buffers haven't been
+ * allocated yet. We don't really care about the race
+ * between setting this flag and actually turning
+ * on the buffer.
+ */
+ global_trace.buffer_disabled = 1;
+}
+EXPORT_SYMBOL_GPL(tracing_off);
+
+/**
+ * tracing_is_on - show state of ring buffers enabled
+ */
+int tracing_is_on(void)
+{
+ if (global_trace.buffer)
+ return ring_buffer_record_is_on(global_trace.buffer);
+ return !global_trace.buffer_disabled;
+}
+EXPORT_SYMBOL_GPL(tracing_is_on);
+
+/**
* trace_wake_up - wake up tasks waiting for trace input
*
* Schedules a delayed work to wake up any task that is blocked on the
@@ -1644,6 +1698,7 @@ __find_next_entry(struct trace_iterator *iter, int *ent_cpu,
int cpu_file = iter->cpu_file;
u64 next_ts = 0, ts;
int next_cpu = -1;
+ int next_size = 0;
int cpu;
/*
@@ -1675,9 +1730,12 @@ __find_next_entry(struct trace_iterator *iter, int *ent_cpu,
next_cpu = cpu;
next_ts = ts;
next_lost = lost_events;
+ next_size = iter->ent_size;
}
}
+ iter->ent_size = next_size;
+
if (ent_cpu)
*ent_cpu = next_cpu;
@@ -4567,6 +4625,55 @@ static __init void create_trace_options_dir(void)
create_trace_option_core_file(trace_options[i], i);
}
+static ssize_t
+rb_simple_read(struct file *filp, char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ struct ring_buffer *buffer = filp->private_data;
+ char buf[64];
+ int r;
+
+ if (buffer)
+ r = ring_buffer_record_is_on(buffer);
+ else
+ r = 0;
+
+ r = sprintf(buf, "%d\n", r);
+
+ return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
+}
+
+static ssize_t
+rb_simple_write(struct file *filp, const char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ struct ring_buffer *buffer = filp->private_data;
+ unsigned long val;
+ int ret;
+
+ ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
+ if (ret)
+ return ret;
+
+ if (buffer) {
+ if (val)
+ ring_buffer_record_on(buffer);
+ else
+ ring_buffer_record_off(buffer);
+ }
+
+ (*ppos)++;
+
+ return cnt;
+}
+
+static const struct file_operations rb_simple_fops = {
+ .open = tracing_open_generic,
+ .read = rb_simple_read,
+ .write = rb_simple_write,
+ .llseek = default_llseek,
+};
+
static __init int tracer_init_debugfs(void)
{
struct dentry *d_tracer;
@@ -4626,6 +4733,9 @@ static __init int tracer_init_debugfs(void)
trace_create_file("trace_clock", 0644, d_tracer, NULL,
&trace_clock_fops);
+ trace_create_file("tracing_on", 0644, d_tracer,
+ global_trace.buffer, &rb_simple_fops);
+
#ifdef CONFIG_DYNAMIC_FTRACE
trace_create_file("dyn_ftrace_total_info", 0444, d_tracer,
&ftrace_update_tot_cnt, &tracing_dyn_info_fops);
@@ -4798,6 +4908,7 @@ __ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
if (ret != TRACE_TYPE_NO_CONSUME)
trace_consume(&iter);
}
+ touch_nmi_watchdog();
trace_printk_seq(&iter.seq);
}
@@ -4863,6 +4974,8 @@ __init static int tracer_alloc_buffers(void)
goto out_free_cpumask;
}
global_trace.entries = ring_buffer_size(global_trace.buffer);
+ if (global_trace.buffer_disabled)
+ tracing_off();
#ifdef CONFIG_TRACER_MAX_TRACE
OpenPOWER on IntegriCloud