[PATCH 3.16 016/254] blktrace: fix trace mutex deadlock

Ben Hutchings
2018-02-28T17:07:34Z

From: Jens Axboe <axboe@kernel.dk>

commit 2967acbb257a6a9bf912f4778b727e00972eac9b upstream.

A previous commit changed the locking around registration/cleanup,
but direct callers of blk_trace_remove() were missed. This means
that if we hit the error path in setup, we will deadlock on
attempting to re-acquire the queue trace mutex.

Fixes: 1f2cac107c59 ("blktrace: fix unlocked access to init/start-stop/teardown")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
kernel/trace/blktrace.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -562,7 +562,7 @@ static int __blk_trace_setup(struct requ
return ret;

if (copy_to_user(arg, &buts, sizeof(buts))) {
- blk_trace_remove(q);
+ __blk_trace_remove(q);
return -EFAULT;
}
return 0;
@@ -608,7 +608,7 @@ static int compat_blk_trace_setup(struct
return ret;

if (copy_to_user(arg, &buts.name, ARRAY_SIZE(buts.name))) {
- blk_trace_remove(q);
+ __blk_trace_remove(q);
return -EFAULT;
}