tracing: pass around ring buffer instead of tracer

The latency tracers (irqsoff and wakeup) can swap trace buffers
on the fly. If an event is happening and has reserved data on one of
the buffers, and the latency tracer swaps the global buffer with the
max buffer, the result is that the event may commit the data to the
wrong buffer.

This patch changes the API to the trace recording to be recieve the
buffer that was used to reserve a commit. Then this buffer can be passed
in to the commit.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 8 insertions, 6 deletions

diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 3f4a251b7d16..b3749a2c3132 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -173,19 +173,20 @@ static int __trace_graph_entry(struct trace_array *tr,
 {
         struct ftrace_event_call *call = &event_funcgraph_entry;
         struct ring_buffer_event *event;
+        struct ring_buffer *buffer = tr->buffer;
         struct ftrace_graph_ent_entry *entry;
 
         if (unlikely(local_read(&__get_cpu_var(ftrace_cpu_disabled))))
                 return 0;
 
-        event = trace_buffer_lock_reserve(tr, TRACE_GRAPH_ENT,
+        event = trace_buffer_lock_reserve(buffer, TRACE_GRAPH_ENT,
                                           sizeof(*entry), flags, pc);
         if (!event)
                 return 0;
         entry   = ring_buffer_event_data(event);
         entry->graph_ent                        = *trace;
-        if (!filter_current_check_discard(call, entry, event))
-                ring_buffer_unlock_commit(tr->buffer, event);
+        if (!filter_current_check_discard(buffer, call, entry, event))
+                ring_buffer_unlock_commit(buffer, event);
 
         return 1;
 }
@@ -236,19 +237,20 @@ static void __trace_graph_return(struct trace_array *tr,
 {
         struct ftrace_event_call *call = &event_funcgraph_exit;
         struct ring_buffer_event *event;
+        struct ring_buffer *buffer = tr->buffer;
         struct ftrace_graph_ret_entry *entry;
 
         if (unlikely(local_read(&__get_cpu_var(ftrace_cpu_disabled))))
                 return;
 
-        event = trace_buffer_lock_reserve(tr, TRACE_GRAPH_RET,
+        event = trace_buffer_lock_reserve(buffer, TRACE_GRAPH_RET,
                                           sizeof(*entry), flags, pc);
         if (!event)
                 return;
         entry   = ring_buffer_event_data(event);
         entry->ret                              = *trace;
-        if (!filter_current_check_discard(call, entry, event))
-                ring_buffer_unlock_commit(tr->buffer, event);
+        if (!filter_current_check_discard(buffer, call, entry, event))
+                ring_buffer_unlock_commit(buffer, event);
 }
 
 void trace_graph_return(struct ftrace_graph_ret *trace)