blktrace: fix blk_probes_ref chaos
[linux-2.6.git] / kernel / trace / blktrace.c
index 5b28f0f..8d6bd12 100644 (file)
@@ -478,7 +478,7 @@ int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
                goto err;
        }
 
-       if (atomic_add_return(1, &blk_probes_ref) == 1)
+       if (atomic_inc_return(&blk_probes_ref) == 1)
                blk_register_tracepoints();
 
        return 0;
@@ -1091,8 +1091,6 @@ static void blk_tracer_print_header(struct seq_file *m)
 
 static void blk_tracer_start(struct trace_array *tr)
 {
-       if (atomic_add_return(1, &blk_probes_ref) == 1)
-               blk_register_tracepoints();
        trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
 }
 
@@ -1107,15 +1105,10 @@ static int blk_tracer_init(struct trace_array *tr)
 static void blk_tracer_stop(struct trace_array *tr)
 {
        trace_flags |= TRACE_ITER_CONTEXT_INFO;
-       if (atomic_dec_and_test(&blk_probes_ref))
-               blk_unregister_tracepoints();
 }
 
 static void blk_tracer_reset(struct trace_array *tr)
 {
-       if (!atomic_read(&blk_probes_ref))
-               return;
-
        blk_tracer_enabled = false;
        blk_tracer_stop(tr);
 }
@@ -1254,6 +1247,9 @@ static int blk_trace_remove_queue(struct request_queue *q)
        if (bt == NULL)
                return -EINVAL;
 
+       if (atomic_dec_and_test(&blk_probes_ref))
+               blk_unregister_tracepoints();
+
        kfree(bt);
        return 0;
 }
@@ -1280,6 +1276,9 @@ static int blk_trace_setup_queue(struct request_queue *q, dev_t dev)
                return -EBUSY;
        }
 
+       if (atomic_inc_return(&blk_probes_ref) == 1)
+               blk_register_tracepoints();
+
        return 0;
 }