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 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -323,12 +323,21 @@ static const char *trace_options[] = {
        "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 @@ static void set_tracer_flags(unsigned int mask, int enabled)
                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 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
        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 @@ static const struct file_operations tracing_mark_fops = {
        .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 @@ static __init int tracer_init_debugfs(void)
        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);

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 64dda57..654fd65 100644 (file)
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -568,6 +568,8 @@ trace_vprintk(unsigned long ip, const char *fmt, va_list args);
 
 extern unsigned long trace_flags;
 
+extern int trace_clock_id;
+
 /* Standard output formatting function used for function return traces */
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 extern enum print_line_t print_graph_function(struct trace_iterator *iter);
@@ -656,9 +658,8 @@ enum trace_iterator_flags {
        TRACE_ITER_PRINTK_MSGONLY       = 0x10000,
        TRACE_ITER_CONTEXT_INFO         = 0x20000, /* Print pid/cpu/time */
        TRACE_ITER_LATENCY_FMT          = 0x40000,
-       TRACE_ITER_GLOBAL_CLK           = 0x80000,
-       TRACE_ITER_SLEEP_TIME           = 0x100000,
-       TRACE_ITER_GRAPH_TIME           = 0x200000,
+       TRACE_ITER_SLEEP_TIME           = 0x80000,
+       TRACE_ITER_GRAPH_TIME           = 0x100000,
 };
 
 /*