perf tools: Move dereference after NULL test

In each case, if the NULL test on thread is needed, then the
dereference should be after the NULL test.

A simplified version of the semantic match that detects this
problem is as follows (http://coccinelle.lip6.fr/):

// <smpl>
@match exists@
expression x, E;
identifier fld;
@@

* x->fld
  ... when != \(x = E\|&x\)
* x == NULL
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
LKML-Reference: <Pine.LNX.4.64.0910170842500.9213@ask.diku.dk>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 2 insertions, 2 deletions

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index ce8459ac2845..4c129ff0bb16 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -80,14 +80,14 @@ process_sample_event(event_t *event, unsigned long offset, unsigned long head)
                 (void *)(long)ip,
                 (long long)period);
 
-        dump_printf(" ... thread: %s:%d\n", thread->comm, thread->pid);
-
         if (thread == NULL) {
                 eprintf("problem processing %d event, skipping it.\n",
                         event->header.type);
                 return -1;
         }
 
+        dump_printf(" ... thread: %s:%d\n", thread->comm, thread->pid);
+
         if (sample_type & PERF_SAMPLE_RAW) {
                 struct {
                         u32 size;