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Diffstat (limited to 'kernel/trace/blktrace.c')
-rw-r--r--kernel/trace/blktrace.c30
1 files changed, 20 insertions, 10 deletions
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 5773f0ba7e76..5ef0484513ec 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -3,6 +3,9 @@
* Copyright (C) 2006 Jens Axboe <axboe@kernel.dk>
*
*/
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
#include <linux/kernel.h>
#include <linux/blkdev.h>
#include <linux/blktrace_api.h>
@@ -344,7 +347,8 @@ static int __blk_trace_remove(struct request_queue *q)
{
struct blk_trace *bt;
- bt = xchg(&q->blk_trace, NULL);
+ bt = rcu_replace_pointer(q->blk_trace, NULL,
+ lockdep_is_held(&q->blk_trace_mutex));
if (!bt)
return -EINVAL;
@@ -494,6 +498,17 @@ static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
*/
strreplace(buts->name, '/', '_');
+ /*
+ * bdev can be NULL, as with scsi-generic, this is a helpful as
+ * we can be.
+ */
+ if (rcu_dereference_protected(q->blk_trace,
+ lockdep_is_held(&q->blk_trace_mutex))) {
+ pr_warn("Concurrent blktraces are not allowed on %s\n",
+ buts->name);
+ return -EBUSY;
+ }
+
bt = kzalloc(sizeof(*bt), GFP_KERNEL);
if (!bt)
return -ENOMEM;
@@ -543,10 +558,7 @@ static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
bt->pid = buts->pid;
bt->trace_state = Blktrace_setup;
- ret = -EBUSY;
- if (cmpxchg(&q->blk_trace, NULL, bt))
- goto err;
-
+ rcu_assign_pointer(q->blk_trace, bt);
get_probe_ref();
ret = 0;
@@ -1629,7 +1641,8 @@ static int blk_trace_remove_queue(struct request_queue *q)
{
struct blk_trace *bt;
- bt = xchg(&q->blk_trace, NULL);
+ bt = rcu_replace_pointer(q->blk_trace, NULL,
+ lockdep_is_held(&q->blk_trace_mutex));
if (bt == NULL)
return -EINVAL;
@@ -1661,10 +1674,7 @@ static int blk_trace_setup_queue(struct request_queue *q,
blk_trace_setup_lba(bt, bdev);
- ret = -EBUSY;
- if (cmpxchg(&q->blk_trace, NULL, bt))
- goto free_bt;
-
+ rcu_assign_pointer(q->blk_trace, bt);
get_probe_ref();
return 0;