Subject: Re: [V9fs-developer] [PATCH] net/9p: fix potential refcnt problem of trans module

From: jiangyiwen <[email-masked]>
Date: Wed, 28 Mar 2018 10:10:08 +0800

On 2018/3/27 20:49, Chengguang Xu wrote:
> 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 <[email-masked]>
> ---
>  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);

I think this should return error if using multiple times
in a mount.

>  			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);

This looks good.

>  	kfree(tmp_options);
>  	return ret;
>  }