tracing: Make __buffer_unlock_commit() always_inline

The function __buffer_unlock_commit() is called in a few places outside of
trace.c. But for the most part, it should really be inlined, as it is in the
hot path of the trace_events. For the callers outside of trace.c, create a
new function trace_buffer_unlock_commit_nostack(), as the reason it was used
was to avoid the stack tracing that trace_buffer_unlock_commit() could do.

Link: http://lkml.kernel.org/r/20161121183700.GW26852@two.firstfloor.org

Reported-by: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

kernel/trace/trace.c

@@ -794,6 +794,22 @@ void tracing_on(void)
 }
 EXPORT_SYMBOL_GPL(tracing_on);
 
+
+static __always_inline void
+__buffer_unlock_commit(struct ring_buffer *buffer, struct ring_buffer_event *event)
+{
+	__this_cpu_write(trace_cmdline_save, true);
+
+	/* If this is the temp buffer, we need to commit fully */
+	if (this_cpu_read(trace_buffered_event) == event) {
+		/* Length is in event->array[0] */
+		ring_buffer_write(buffer, event->array[0], &event->array[1]);
+		/* Release the temp buffer */
+		this_cpu_dec(trace_buffered_event_cnt);
+	} else
+		ring_buffer_unlock_commit(buffer, event);
+}
+
 /**
  * __trace_puts - write a constant string into the trace buffer.
  * @ip:	   The address of the caller
@@ -2059,21 +2075,6 @@ void trace_buffered_event_disable(void)
 	preempt_enable();
 }
 
-void
-__buffer_unlock_commit(struct ring_buffer *buffer, struct ring_buffer_event *event)
-{
-	__this_cpu_write(trace_cmdline_save, true);
-
-	/* If this is the temp buffer, we need to commit fully */
-	if (this_cpu_read(trace_buffered_event) == event) {
-		/* Length is in event->array[0] */
-		ring_buffer_write(buffer, event->array[0], &event->array[1]);
-		/* Release the temp buffer */
-		this_cpu_dec(trace_buffered_event_cnt);
-	} else
-		ring_buffer_unlock_commit(buffer, event);
-}
-
 static struct ring_buffer *temp_buffer;
 
 struct ring_buffer_event *
@@ -2214,6 +2215,16 @@ void trace_buffer_unlock_commit_regs(struct trace_array *tr,
 	ftrace_trace_userstack(buffer, flags, pc);
 }
 
+/*
+ * Similar to trace_buffer_unlock_commit_regs() but do not dump stack.
+ */
+void
+trace_buffer_unlock_commit_nostack(struct ring_buffer *buffer,
+				   struct ring_buffer_event *event)
+{
+	__buffer_unlock_commit(buffer, event);
+}
+
 static void
 trace_process_export(struct trace_export *export,
 	       struct ring_buffer_event *event)

kernel/trace/trace.h

@@ -602,8 +602,8 @@ struct trace_entry *tracing_get_trace_entry(struct trace_array *tr,
 struct trace_entry *trace_find_next_entry(struct trace_iterator *iter,
 					  int *ent_cpu, u64 *ent_ts);
 
-void __buffer_unlock_commit(struct ring_buffer *buffer,
+void trace_buffer_unlock_commit_nostack(struct ring_buffer *buffer,
-			    struct ring_buffer_event *event);
+					struct ring_buffer_event *event);
 
 int trace_empty(struct trace_iterator *iter);
 

kernel/trace/trace_branch.c

@@ -81,7 +81,7 @@ probe_likely_condition(struct ftrace_branch_data *f, int val, int expect)
 	entry->correct = val == expect;
 
 	if (!call_filter_check_discard(call, entry, buffer, event))
-		__buffer_unlock_commit(buffer, event);
+		trace_buffer_unlock_commit_nostack(buffer, event);
 
  out:
 	current->trace_recursion &= ~TRACE_BRANCH_BIT;

kernel/trace/trace_functions_graph.c

@@ -358,7 +358,7 @@ int __trace_graph_entry(struct trace_array *tr,
 	entry	= ring_buffer_event_data(event);
 	entry->graph_ent			= *trace;
 	if (!call_filter_check_discard(call, entry, buffer, event))
-		__buffer_unlock_commit(buffer, event);
+		trace_buffer_unlock_commit_nostack(buffer, event);
 
 	return 1;
 }
@@ -469,7 +469,7 @@ void __trace_graph_return(struct trace_array *tr,
 	entry	= ring_buffer_event_data(event);
 	entry->ret				= *trace;
 	if (!call_filter_check_discard(call, entry, buffer, event))
-		__buffer_unlock_commit(buffer, event);
+		trace_buffer_unlock_commit_nostack(buffer, event);
 }
 
 void trace_graph_return(struct ftrace_graph_ret *trace)

kernel/trace/trace_hwlat.c

@@ -127,7 +127,7 @@ static void trace_hwlat_sample(struct hwlat_sample *sample)
 	entry->nmi_count		= sample->nmi_count;
 
 	if (!call_filter_check_discard(call, entry, buffer, event))
-		__buffer_unlock_commit(buffer, event);
+		trace_buffer_unlock_commit_nostack(buffer, event);
 }
 
 /* Macros to encapsulate the time capturing infrastructure */