net/9p/client.c: fix potential refcnt problem of trans module

When specifying trans_mod multiple times in a mount, it will cause an
inaccurate refcount of the trans module.  Also, in the error case of
option parsing, we should put the trans module if we have already got
it.

Link: http://lkml.kernel.org/r/1522154942-57339-1-git-send-email-cgxu519@gmx.com
Signed-off-by: Chengguang Xu <cgxu519@gmx.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: David Miller <davem@davemloft.net>
Cc: Eric Van Hensbergen <ericvh@gmail.com>
Cc: Ron Minnich <rminnich@sandia.gov>
Cc: Latchesar Ionkov <lucho@ionkov.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 1 deletions

diff --git a/net/9p/client.c b/net/9p/client.c
index e6cae8332e2e..21e6df1cc70f 100644
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -190,7 +190,9 @@ static int parse_opts(char *opts, struct p9_client *clnt)
                                 p9_debug(P9_DEBUG_ERROR,
                                          "problem allocating copy of trans arg\n");
                                 goto free_and_return;
-                         }
+                        }
+
+                        v9fs_put_trans(clnt->trans_mod);
                         clnt->trans_mod = v9fs_get_trans_by_name(s);
                         if (clnt->trans_mod == NULL) {
                                 pr_info("Could not find request transport: %s\n",
@@ -226,6 +228,7 @@ static int parse_opts(char *opts, struct p9_client *clnt)
         }
 
 free_and_return:
+        v9fs_put_trans(clnt->trans_mod);
         kfree(tmp_options);
         return ret;
 }