Bluetooth: cmtp: Fix module reference

We cannot call module_put(THIS_MODULE) if this is our last reference. Otherwise,
this call may cleanup our module before it returns.

Gladly, the kthread API provides a simple wrapper for us. So lets use
module_put_and_exit() to avoid a race condition with the module cleanup code.

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>

1 files changed, 3 insertions, 2 deletions

diff --git a/net/bluetooth/cmtp/core.c b/net/bluetooth/cmtp/core.c
index 7d00ddf9e9dc..5a6e634f7fca 100644
--- a/net/bluetooth/cmtp/core.c
+++ b/net/bluetooth/cmtp/core.c
@@ -67,14 +67,12 @@ static struct cmtp_session *__cmtp_get_session(bdaddr_t *bdaddr)
 
 static void __cmtp_link_session(struct cmtp_session *session)
 {
-        __module_get(THIS_MODULE);
         list_add(&session->list, &cmtp_session_list);
 }
 
 static void __cmtp_unlink_session(struct cmtp_session *session)
 {
         list_del(&session->list);
-        module_put(THIS_MODULE);
 }
 
 static void __cmtp_copy_session(struct cmtp_session *session, struct cmtp_conninfo *ci)
@@ -327,6 +325,7 @@ static int cmtp_session(void *arg)
         up_write(&cmtp_session_sem);
 
         kfree(session);
+        module_put_and_exit(0);
         return 0;
 }
 
@@ -376,9 +375,11 @@ int cmtp_add_connection(struct cmtp_connadd_req *req, struct socket *sock)
 
         __cmtp_link_session(session);
 
+        __module_get(THIS_MODULE);
         session->task = kthread_run(cmtp_session, session, "kcmtpd_ctr_%d",
                                                                 session->num);
         if (IS_ERR(session->task)) {
+                module_put(THIS_MODULE);
                 err = PTR_ERR(session->task);
                 goto unlink;
         }