On 2018/7/6 17:42, piaojun wrote:
>>From my test, 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.
>
> Fixes: 9421c3e64137ec ("net/9p/client.c: fix potential refcnt problem of
> trans module")
>
> Signed-off-by: Jun Piao <piao...@huawei.com>
It looks good to me.
Reviewed-by: Yiwen Jiang <jiangyi...@huawei.com>
> ---
> net/9p/client.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/net/9p/client.c b/net/9p/client.c
> index 18c5271..5c13431 100644
> --- 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;
> }
>
