cifs: take module reference when starting cifsd

cifsd can outlive the last cifs mount. We need to hold a module
reference until it exits to prevent someone from unplugging
the module until we're ready.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 8 insertions, 1 deletions

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index c7d341714586..701daf411a4b 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -776,7 +776,7 @@ multi_t2_fnd:
                 set_current_state(TASK_RUNNING);
         }
 
-        return 0;
+        module_put_and_exit(0);
 }
 
 /* extract the host portion of the UNC string */
@@ -2176,10 +2176,17 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb,
                         so no need to spinlock this init of tcpStatus */
                         srvTcp->tcpStatus = CifsNew;
                         init_MUTEX(&srvTcp->tcpSem);
+
+                        /*
+                         * since we're in a cifs function already, we know that
+                         * this will succeed. No need for try_module_get().
+                         */
+                        __module_get(THIS_MODULE);
                         srvTcp->tsk = kthread_run((void *)(void *)cifs_demultiplex_thread, srvTcp, "cifsd");
                         if (IS_ERR(srvTcp->tsk)) {
                                 rc = PTR_ERR(srvTcp->tsk);
                                 cERROR(1, ("error %d create cifsd thread", rc));
+                                module_put(THIS_MODULE);
                                 srvTcp->tsk = NULL;
                                 sock_release(csocket);
                                 kfree(srvTcp->hostname);