netdev - [PATCH] net/9p: fix potential refcnt problem of trans module

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Date:   Tue, 27 Mar 2018 20:49:02 +0800
From:   Chengguang Xu <cgxu519@....com>
To:     ericvh@...il.com, rminnich@...dia.gov, lucho@...kov.net,
        davem@...emloft.net
Cc:     v9fs-developer@...ts.sourceforge.net, netdev@...r.kernel.org,
        Chengguang Xu <cgxu519@....com>
Subject: [PATCH] net/9p: fix potential refcnt problem of trans module

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

Signed-off-by: Chengguang Xu <cgxu519@....com>
---
 net/9p/client.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/9p/client.c b/net/9p/client.c
index b433aff..7ccfb4b 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;
 }
-- 
1.8.3.1