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>

diff --git a/kernel/trace/trace_branch.c b/kernel/trace/trace_branch.c
index 216e2dd302a0fdf8ef026d6d932a90d2e6653105..4a194f08f88cc8d7143d5fbd1d43c0efc2013292 100644 (file)
--- 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);