ftrace: Move setting of clock-source out of options
There are many clock sources for the tracing system but we can only
enable/disable one at a time with the trace/options file.
We can move the setting of clock-source out of options and add a separate
file for it:
# cat trace_clock
[local] global
# echo global > trace_clock
# cat trace_clock
local [global]
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
LKML-Reference: <4A939D08.6050604@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 8ac2043..63dbc7f 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -323,12 +323,21 @@
"printk-msg-only",
"context-info",
"latency-format",
- "global-clock",
"sleep-time",
"graph-time",
NULL
};
+static struct {
+ u64 (*func)(void);
+ const char *name;
+} trace_clocks[] = {
+ { trace_clock_local, "local" },
+ { trace_clock_global, "global" },
+};
+
+int trace_clock_id;
+
/*
* ftrace_max_lock is used to protect the swapping of buffers
* when taking a max snapshot. The buffers themselves are
@@ -2159,22 +2168,6 @@
trace_flags |= mask;
else
trace_flags &= ~mask;
-
- if (mask == TRACE_ITER_GLOBAL_CLK) {
- u64 (*func)(void);
-
- if (enabled)
- func = trace_clock_global;
- else
- func = trace_clock_local;
-
- mutex_lock(&trace_types_lock);
- ring_buffer_set_clock(global_trace.buffer, func);
-
- if (max_tr.buffer)
- ring_buffer_set_clock(max_tr.buffer, func);
- mutex_unlock(&trace_types_lock);
- }
}
static ssize_t
@@ -3142,6 +3135,62 @@
return cnt;
}
+static ssize_t tracing_clock_read(struct file *filp, char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ char buf[64];
+ int bufiter = 0;
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(trace_clocks); i++)
+ bufiter += snprintf(buf + bufiter, sizeof(buf) - bufiter,
+ "%s%s%s%s", i ? " " : "",
+ i == trace_clock_id ? "[" : "", trace_clocks[i].name,
+ i == trace_clock_id ? "]" : "");
+ bufiter += snprintf(buf + bufiter, sizeof(buf) - bufiter, "\n");
+
+ return simple_read_from_buffer(ubuf, cnt, ppos, buf, bufiter);
+}
+
+static ssize_t tracing_clock_write(struct file *filp, const char __user *ubuf,
+ size_t cnt, loff_t *fpos)
+{
+ char buf[64];
+ const char *clockstr;
+ int i;
+
+ if (cnt >= sizeof(buf))
+ return -EINVAL;
+
+ if (copy_from_user(&buf, ubuf, cnt))
+ return -EFAULT;
+
+ buf[cnt] = 0;
+
+ clockstr = strstrip(buf);
+
+ for (i = 0; i < ARRAY_SIZE(trace_clocks); i++) {
+ if (strcmp(trace_clocks[i].name, clockstr) == 0)
+ break;
+ }
+ if (i == ARRAY_SIZE(trace_clocks))
+ return -EINVAL;
+
+ trace_clock_id = i;
+
+ mutex_lock(&trace_types_lock);
+
+ ring_buffer_set_clock(global_trace.buffer, trace_clocks[i].func);
+ if (max_tr.buffer)
+ ring_buffer_set_clock(max_tr.buffer, trace_clocks[i].func);
+
+ mutex_unlock(&trace_types_lock);
+
+ *fpos += cnt;
+
+ return cnt;
+}
+
static const struct file_operations tracing_max_lat_fops = {
.open = tracing_open_generic,
.read = tracing_max_lat_read,
@@ -3179,6 +3228,12 @@
.write = tracing_mark_write,
};
+static const struct file_operations trace_clock_fops = {
+ .open = tracing_open_generic,
+ .read = tracing_clock_read,
+ .write = tracing_clock_write,
+};
+
struct ftrace_buffer_info {
struct trace_array *tr;
void *spare;
@@ -3918,6 +3973,9 @@
trace_create_file("saved_cmdlines", 0444, d_tracer,
NULL, &tracing_saved_cmdlines_fops);
+ trace_create_file("trace_clock", 0644, d_tracer, NULL,
+ &trace_clock_fops);
+
#ifdef CONFIG_DYNAMIC_FTRACE
trace_create_file("dyn_ftrace_total_info", 0444, d_tracer,
&ftrace_update_tot_cnt, &tracing_dyn_info_fops);