net/9p/client.c: put refcount of trans_mod in error case in parse_opts()

In my testing, the second mount will fail after umounting successfully.
The reason is that we put refcount of trans_mod in the correct case
rather than the error case in parse_opts() at last.  That will cause the
refcount decrease to -1, and when we try to get trans_mod again in
try_module_get(), we could only increase refcount to 0 which will cause
failure as follows:

parse_opts
  v9fs_get_trans_by_name
    try_module_get : return NULL to caller which cause error

So we should put refcount of trans_mod in error case.

Link: http://lkml.kernel.org/r/[email protected]
Fixes: 9421c3e64137ec ("net/9p/client.c: fix potential refcnt problem of trans module")
Signed-off-by: Jun Piao <[email protected]>
Reviewed-by: Yiwen Jiang <[email protected]>
Reviewed-by: Greg Kurz <[email protected]>
Reviewed-by: Dominique Martinet <[email protected]>
Tested-by: Dominique Martinet <[email protected]>
Cc: Eric Van Hensbergen <[email protected]>
Cc: Ron Minnich <[email protected]>
Cc: Latchesar Ionkov <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

diff --git a/net/9p/client.c b/net/9p/client.c
index 18c5271910dc2c1e1715efcd2b448b7cee6a844b..5c1343195292c8f474ff683c73c8f73aa51843a0 100644 (file)
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -225,7 +225,8 @@ static int parse_opts(char *opts, struct p9_client *clnt)
        }
 
 free_and_return:
-       v9fs_put_trans(clnt->trans_mod);
+       if (ret)
+               v9fs_put_trans(clnt->trans_mod);
        kfree(tmp_options);
        return ret;
 }