tracing: user local buffer variable for trace branch tracer

Just using the tr->buffer for the API to trace_buffer_lock_reserve
is not good enough. This is because the tr->buffer may change, and we
do not want to commit with a different buffer that we reserved from.

This patch uses a local variable to hold the buffer that was used to
reserve and commit with.

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

1 files changed, 5 insertions, 3 deletions

diff --git a/kernel/trace/trace_branch.c b/kernel/trace/trace_branch.c
index 216e2dd302a0..4a194f08f88c 100644
--- a/kernel/trace/trace_branch.c
+++ b/kernel/trace/trace_branch.c
@@ -34,6 +34,7 @@ probe_likely_condition(struct ftrace_branch_data *f, int val, int expect)
         struct trace_array *tr = branch_tracer;
         struct ring_buffer_event *event;
         struct trace_branch *entry;
+        struct ring_buffer *buffer;
         unsigned long flags;
         int cpu, pc;
         const char *p;
@@ -54,7 +55,8 @@ probe_likely_condition(struct ftrace_branch_data *f, int val, int expect)
                 goto out;
 
         pc = preempt_count();
-        event = trace_buffer_lock_reserve(tr->buffer, TRACE_BRANCH,
+        buffer = tr->buffer;
+        event = trace_buffer_lock_reserve(buffer, TRACE_BRANCH,
                                           sizeof(*entry), flags, pc);
         if (!event)
                 goto out;
@@ -74,8 +76,8 @@ probe_likely_condition(struct ftrace_branch_data *f, int val, int expect)
         entry->line = f->line;
         entry->correct = val == expect;
 
-        if (!filter_check_discard(call, entry, tr->buffer, event))
-                ring_buffer_unlock_commit(tr->buffer, event);
+        if (!filter_check_discard(call, entry, buffer, event))
+                ring_buffer_unlock_commit(buffer, event);
 
  out:
         atomic_dec(&tr->data[cpu]->disabled);