Merge tag 'trace-v4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracking updates from Steven Rostedt:
 "Most of the changes are clean ups and small fixes.  Some of them have
  stable tags to them.  I searched through my INBOX just as the merge
  window opened and found lots of patches to pull.  I ran them through
  all my tests and they were in linux-next for a few days.

  Features added this release:
  ----------------------------

   - Module globbing.  You can now filter function tracing to several
     modules.  # echo '*:mod:*snd*' > set_ftrace_filter (Dmitry Safonov)

   - Tracer specific options are now visible even when the tracer is not
     active.  It was rather annoying that you can only see and modify
     tracer options after enabling the tracer.  Now they are in the
     options/ directory even when the tracer is not active.  Although
     they are still only visible when the tracer is active in the
     trace_options file.

   - Trace options are now per instance (although some of the tracer
     specific options are global)

   - New tracefs file: set_event_pid.  If any pid is added to this file,
     then all events in the instance will filter out events that are not
     part of this pid.  sched_switch and sched_wakeup events handle next
     and the wakee pids"

* tag 'trace-v4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (68 commits)
  tracefs: Fix refcount imbalance in start_creating()
  tracing: Put back comma for empty fields in boot string parsing
  tracing: Apply tracer specific options from kernel command line.
  tracing: Add some documentation about set_event_pid
  ring_buffer: Remove unneeded smp_wmb() before wakeup of reader benchmark
  tracing: Allow dumping traces without tracking trace started cpus
  ring_buffer: Fix more races when terminating the producer in the benchmark
  ring_buffer: Do no not complete benchmark reader too early
  tracing: Remove redundant TP_ARGS redefining
  tracing: Rename max_stack_lock to stack_trace_max_lock
  tracing: Allow arch-specific stack tracer
  recordmcount: arm64: Replace the ignored mcount call into nop
  recordmcount: Fix endianness handling bug for nop_mcount
  tracepoints: Fix documentation of RCU lockdep checks
  tracing: ftrace_event_is_function() can return boolean
  tracing: is_legal_op() can return boolean
  ring-buffer: rb_event_is_commit() can return boolean
  ring-buffer: rb_per_cpu_empty() can return boolean
  ring_buffer: ring_buffer_empty{cpu}() can return boolean
  ring-buffer: rb_is_reader_page() can return boolean
  ...

1 files changed, 50 insertions, 11 deletions

diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 3490407dc7b7..ecd536de603a 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -91,11 +91,13 @@ static void debug_print_probes(struct tracepoint_func *funcs)
 		printk(KERN_DEBUG "Probe %d : %p\n", i, funcs[i].func);
 }
 
-static struct tracepoint_func *func_add(struct tracepoint_func **funcs,
-		struct tracepoint_func *tp_func)
+static struct tracepoint_func *
+func_add(struct tracepoint_func **funcs, struct tracepoint_func *tp_func,
+	 int prio)
 {
-	int nr_probes = 0;
 	struct tracepoint_func *old, *new;
+	int nr_probes = 0;
+	int pos = -1;
 
 	if (WARN_ON(!tp_func->func))
 		return ERR_PTR(-EINVAL);
@@ -104,18 +106,33 @@ static struct tracepoint_func *func_add(struct tracepoint_func **funcs,
 	old = *funcs;
 	if (old) {
 		/* (N -> N+1), (N != 0, 1) probes */
-		for (nr_probes = 0; old[nr_probes].func; nr_probes++)
+		for (nr_probes = 0; old[nr_probes].func; nr_probes++) {
+			/* Insert before probes of lower priority */
+			if (pos < 0 && old[nr_probes].prio < prio)
+				pos = nr_probes;
 			if (old[nr_probes].func == tp_func->func &&
 			    old[nr_probes].data == tp_func->data)
 				return ERR_PTR(-EEXIST);
+		}
 	}
 	/* + 2 : one for new probe, one for NULL func */
 	new = allocate_probes(nr_probes + 2);
 	if (new == NULL)
 		return ERR_PTR(-ENOMEM);
-	if (old)
-		memcpy(new, old, nr_probes * sizeof(struct tracepoint_func));
-	new[nr_probes] = *tp_func;
+	if (old) {
+		if (pos < 0) {
+			pos = nr_probes;
+			memcpy(new, old, nr_probes * sizeof(struct tracepoint_func));
+		} else {
+			/* Copy higher priority probes ahead of the new probe */
+			memcpy(new, old, pos * sizeof(struct tracepoint_func));
+			/* Copy the rest after it. */
+			memcpy(new + pos + 1, old + pos,
+			       (nr_probes - pos) * sizeof(struct tracepoint_func));
+		}
+	} else
+		pos = 0;
+	new[pos] = *tp_func;
 	new[nr_probes + 1].func = NULL;
 	*funcs = new;
 	debug_print_probes(*funcs);
@@ -174,7 +191,7 @@ static void *func_remove(struct tracepoint_func **funcs,
  * Add the probe function to a tracepoint.
  */
 static int tracepoint_add_func(struct tracepoint *tp,
-		struct tracepoint_func *func)
+			       struct tracepoint_func *func, int prio)
 {
 	struct tracepoint_func *old, *tp_funcs;
 
@@ -183,7 +200,7 @@ static int tracepoint_add_func(struct tracepoint *tp,
 
 	tp_funcs = rcu_dereference_protected(tp->funcs,
 			lockdep_is_held(&tracepoints_mutex));
-	old = func_add(&tp_funcs, func);
+	old = func_add(&tp_funcs, func, prio);
 	if (IS_ERR(old)) {
 		WARN_ON_ONCE(1);
 		return PTR_ERR(old);
@@ -240,6 +257,7 @@ static int tracepoint_remove_func(struct tracepoint *tp,
  * @tp: tracepoint
  * @probe: probe handler
  * @data: tracepoint data
+ * @prio: priority of this function over other registered functions
  *
  * Returns 0 if ok, error value on error.
  * Note: if @tp is within a module, the caller is responsible for
@@ -247,7 +265,8 @@ static int tracepoint_remove_func(struct tracepoint *tp,
  * performed either with a tracepoint module going notifier, or from
  * within module exit functions.
  */
-int tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data)
+int tracepoint_probe_register_prio(struct tracepoint *tp, void *probe,
+				   void *data, int prio)
 {
 	struct tracepoint_func tp_func;
 	int ret;
@@ -255,10 +274,30 @@ int tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data)
 	mutex_lock(&tracepoints_mutex);
 	tp_func.func = probe;
 	tp_func.data = data;
-	ret = tracepoint_add_func(tp, &tp_func);
+	tp_func.prio = prio;
+	ret = tracepoint_add_func(tp, &tp_func, prio);
 	mutex_unlock(&tracepoints_mutex);
 	return ret;
 }
+EXPORT_SYMBOL_GPL(tracepoint_probe_register_prio);
+
+/**
+ * tracepoint_probe_register -  Connect a probe to a tracepoint
+ * @tp: tracepoint
+ * @probe: probe handler
+ * @data: tracepoint data
+ * @prio: priority of this function over other registered functions
+ *
+ * Returns 0 if ok, error value on error.
+ * Note: if @tp is within a module, the caller is responsible for
+ * unregistering the probe before the module is gone. This can be
+ * performed either with a tracepoint module going notifier, or from
+ * within module exit functions.
+ */
+int tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data)
+{
+	return tracepoint_probe_register_prio(tp, probe, data, TRACEPOINT_DEFAULT_PRIO);
+}
 EXPORT_SYMBOL_GPL(tracepoint_probe_register);
 
 /**