1 files changed, 53 insertions, 12 deletions

diff --git a/kernel/trace/trace_nop.c b/kernel/trace/trace_nop.c
index 4592b4862515..b9767acd30ac 100644
--- a/kernel/trace/trace_nop.c
+++ b/kernel/trace/trace_nop.c
@@ -12,6 +12,27 @@
 
 #include "trace.h"
 
+/* Our two options */
+enum {
+        TRACE_NOP_OPT_ACCEPT = 0x1,
+        TRACE_NOP_OPT_REFUSE = 0x2
+};
+
+/* Options for the tracer (see trace_options file) */
+static struct tracer_opt nop_opts[] = {
+        /* Option that will be accepted by set_flag callback */
+        { TRACER_OPT(test_nop_accept, TRACE_NOP_OPT_ACCEPT) },
+        /* Option that will be refused by set_flag callback */
+        { TRACER_OPT(test_nop_refuse, TRACE_NOP_OPT_REFUSE) },
+        { } /* Always set a last empty entry */
+};
+
+static struct tracer_flags nop_flags = {
+        /* You can check your flags value here when you want. */
+        .val = 0, /* By default: all flags disabled */
+        .opts = nop_opts
+};
+
 static struct trace_array       *ctx_trace;
 
 static void start_nop_trace(struct trace_array *tr)
@@ -24,7 +45,7 @@ static void stop_nop_trace(struct trace_array *tr)
         /* Nothing to do! */
 }
 
-static void nop_trace_init(struct trace_array *tr)
+static int nop_trace_init(struct trace_array *tr)
 {
         int cpu;
         ctx_trace = tr;
@@ -32,33 +53,53 @@ static void nop_trace_init(struct trace_array *tr)
         for_each_online_cpu(cpu)
                 tracing_reset(tr, cpu);
 
-        if (tr->ctrl)
-                start_nop_trace(tr);
+        start_nop_trace(tr);
+        return 0;
 }
 
 static void nop_trace_reset(struct trace_array *tr)
 {
-        if (tr->ctrl)
-                stop_nop_trace(tr);
+        stop_nop_trace(tr);
 }
 
-static void nop_trace_ctrl_update(struct trace_array *tr)
+/* It only serves as a signal handler and a callback to
+ * accept or refuse tthe setting of a flag.
+ * If you don't implement it, then the flag setting will be
+ * automatically accepted.
+ */
+static int nop_set_flag(u32 old_flags, u32 bit, int set)
 {
-        /* When starting a new trace, reset the buffers */
-        if (tr->ctrl)
-                start_nop_trace(tr);
-        else
-                stop_nop_trace(tr);
+        /*
+         * Note that you don't need to update nop_flags.val yourself.
+         * The tracing Api will do it automatically if you return 0
+         */
+        if (bit == TRACE_NOP_OPT_ACCEPT) {
+                printk(KERN_DEBUG "nop_test_accept flag set to %d: we accept."
+                        " Now cat trace_options to see the result\n",
+                        set);
+                return 0;
+        }
+
+        if (bit == TRACE_NOP_OPT_REFUSE) {
+                printk(KERN_DEBUG "nop_test_refuse flag set to %d: we refuse."
+                        "Now cat trace_options to see the result\n",
+                        set);
+                return -EINVAL;
+        }
+
+        return 0;
 }
 
+
 struct tracer nop_trace __read_mostly =
 {
         .name           = "nop",
         .init           = nop_trace_init,
         .reset          = nop_trace_reset,
-        .ctrl_update    = nop_trace_ctrl_update,
 #ifdef CONFIG_FTRACE_SELFTEST
         .selftest       = trace_selftest_startup_nop,
 #endif
+        .flags          = &nop_flags,
+        .set_flag       = nop_set_flag
 };