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-rw-r--r--kernel/trace/blktrace.c32
1 files changed, 22 insertions, 10 deletions
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index ea57dd94b2b2..206e0e2ace53 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -66,7 +66,8 @@ static struct tracer_flags blk_tracer_flags = {
};
/* Global reference count of probes */
-static atomic_t blk_probes_ref = ATOMIC_INIT(0);
+static DEFINE_MUTEX(blk_probe_mutex);
+static int blk_probes_ref;
static void blk_register_tracepoints(void);
static void blk_unregister_tracepoints(void);
@@ -329,11 +330,26 @@ static void blk_trace_free(struct blk_trace *bt)
kfree(bt);
}
+static void get_probe_ref(void)
+{
+ mutex_lock(&blk_probe_mutex);
+ if (++blk_probes_ref == 1)
+ blk_register_tracepoints();
+ mutex_unlock(&blk_probe_mutex);
+}
+
+static void put_probe_ref(void)
+{
+ mutex_lock(&blk_probe_mutex);
+ if (!--blk_probes_ref)
+ blk_unregister_tracepoints();
+ mutex_unlock(&blk_probe_mutex);
+}
+
static void blk_trace_cleanup(struct blk_trace *bt)
{
blk_trace_free(bt);
- if (atomic_dec_and_test(&blk_probes_ref))
- blk_unregister_tracepoints();
+ put_probe_ref();
}
static int __blk_trace_remove(struct request_queue *q)
@@ -549,8 +565,7 @@ static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
if (cmpxchg(&q->blk_trace, NULL, bt))
goto err;
- if (atomic_inc_return(&blk_probes_ref) == 1)
- blk_register_tracepoints();
+ get_probe_ref();
ret = 0;
err:
@@ -1596,9 +1611,7 @@ 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();
-
+ put_probe_ref();
blk_trace_free(bt);
return 0;
}
@@ -1629,8 +1642,7 @@ static int blk_trace_setup_queue(struct request_queue *q,
if (cmpxchg(&q->blk_trace, NULL, bt))
goto free_bt;
- if (atomic_inc_return(&blk_probes_ref) == 1)
- blk_register_tracepoints();
+ get_probe_ref();
return 0;
free_bt: