1 files changed, 11 insertions, 16 deletions

diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 90e72a0c3..a990824c8 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -103,7 +103,7 @@ record_it:
 		memcpy((void *) t + sizeof(*t), data, len);
 
 		if (blk_tracer)
-			trace_buffer_unlock_commit(buffer, event, 0, pc);
+			trace_buffer_unlock_commit(blk_tr, buffer, event, 0, pc);
 	}
 }
 
@@ -278,7 +278,7 @@ record_it:
 			memcpy((void *) t + sizeof(*t), pdu_data, pdu_len);
 
 		if (blk_tracer) {
-			trace_buffer_unlock_commit(buffer, event, 0, pc);
+			trace_buffer_unlock_commit(blk_tr, buffer, event, 0, pc);
 			return;
 		}
 	}
@@ -437,7 +437,7 @@ int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 		       struct block_device *bdev,
 		       struct blk_user_trace_setup *buts)
 {
-	struct blk_trace *old_bt, *bt = NULL;
+	struct blk_trace *bt = NULL;
 	struct dentry *dir = NULL;
 	int ret;
 
@@ -519,11 +519,8 @@ int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 	bt->trace_state = Blktrace_setup;
 
 	ret = -EBUSY;
-	old_bt = xchg(&q->blk_trace, bt);
-	if (old_bt) {
-		(void) xchg(&q->blk_trace, old_bt);
+	if (cmpxchg(&q->blk_trace, NULL, bt))
 		goto err;
-	}
 
 	if (atomic_inc_return(&blk_probes_ref) == 1)
 		blk_register_tracepoints();
@@ -1343,6 +1340,7 @@ static const struct {
 static enum print_line_t print_one_line(struct trace_iterator *iter,
 					bool classic)
 {
+	struct trace_array *tr = iter->tr;
 	struct trace_seq *s = &iter->seq;
 	const struct blk_io_trace *t;
 	u16 what;
@@ -1351,7 +1349,7 @@ static enum print_line_t print_one_line(struct trace_iterator *iter,
 
 	t	   = te_blk_io_trace(iter->ent);
 	what	   = t->action & ((1 << BLK_TC_SHIFT) - 1);
-	long_act   = !!(trace_flags & TRACE_ITER_VERBOSE);
+	long_act   = !!(tr->trace_flags & TRACE_ITER_VERBOSE);
 	log_action = classic ? &blk_log_action_classic : &blk_log_action;
 
 	if (t->action == BLK_TN_MESSAGE) {
@@ -1413,9 +1411,9 @@ blk_tracer_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
 	/* don't output context-info for blk_classic output */
 	if (bit == TRACE_BLK_OPT_CLASSIC) {
 		if (set)
-			trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
+			tr->trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
 		else
-			trace_flags |= TRACE_ITER_CONTEXT_INFO;
+			tr->trace_flags |= TRACE_ITER_CONTEXT_INFO;
 	}
 	return 0;
 }
@@ -1481,7 +1479,7 @@ static int blk_trace_remove_queue(struct request_queue *q)
 static int blk_trace_setup_queue(struct request_queue *q,
 				 struct block_device *bdev)
 {
-	struct blk_trace *old_bt, *bt = NULL;
+	struct blk_trace *bt = NULL;
 	int ret = -ENOMEM;
 
 	bt = kzalloc(sizeof(*bt), GFP_KERNEL);
@@ -1497,12 +1495,9 @@ static int blk_trace_setup_queue(struct request_queue *q,
 
 	blk_trace_setup_lba(bt, bdev);
 
-	old_bt = xchg(&q->blk_trace, bt);
-	if (old_bt != NULL) {
-		(void)xchg(&q->blk_trace, old_bt);
-		ret = -EBUSY;
+	ret = -EBUSY;
+	if (cmpxchg(&q->blk_trace, NULL, bt))
 		goto free_bt;
-	}
 
 	if (atomic_inc_return(&blk_probes_ref) == 1)
 		blk_register_tracepoints();