Re: [PATCH v2] SUNRPC: check current nsproxy before set of node name on client creation

Jeff Layton
2012-08-13T12:11:09Z

On Mon, 13 Aug 2012 15:37:31 +0400
Stanislav Kinsbursky <skinsbursky@parallels.com> wrote:

> v2:
> 1) rpc_clnt_set_nodename() prototype updated.
> 2) fixed errors in comment.
>
> When child reaper exits, it can destroy mount namespace it belongs to, and if
> there are NFS mounts inside, then it will try to umount them. But in this
> point current->nsproxy is set to NULL and all namespaces will be destroyed one
> by one. I.e. we can't dereference current->nsproxy to obtain uts namespace.
>
> Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
> ---
> net/sunrpc/clnt.c | 16 +++++++++++++---
> 1 files changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
> index 9a9676e..8fbcbc8 100644
> --- a/net/sunrpc/clnt.c
> +++ b/net/sunrpc/clnt.c
> @@ -277,8 +277,18 @@ void rpc_clients_notifier_unregister(void)
> return rpc_pipefs_notifier_unregister(&rpc_clients_block);
> }
>
> -static void rpc_clnt_set_nodename(struct rpc_clnt *clnt, const char *nodename)
> +static void rpc_clnt_set_nodename(struct rpc_clnt *clnt)
> {
> + const char *nodename;
> +
> + /*
> + * We have to protect against dying child reaper, which has released
> + * its nsproxy already and is trying to destroy mount namespace.
> + */
> + if (current->nsproxy == NULL)
> + return;
> +
> + nodename = utsname()->nodename;
> clnt->cl_nodelen = strlen(nodename);
> if (clnt->cl_nodelen > UNX_MAXNODENAME)
> clnt->cl_nodelen = UNX_MAXNODENAME;
> @@ -365,7 +375,7 @@ static struct rpc_clnt * rpc_new_client(const struct rpc_create_args *args, stru
> }
>
> /* save the nodename */
> - rpc_clnt_set_nodename(clnt, utsname()->nodename);
> + rpc_clnt_set_nodename(clnt);
> rpc_register_client(clnt);
> return clnt;
>
> @@ -524,7 +534,7 @@ rpc_clone_client(struct rpc_clnt *clnt)
> err = rpc_setup_pipedir(new, clnt->cl_program->pipe_dir_name);
> if (err != 0)
> goto out_no_path;
> - rpc_clnt_set_nodename(new, utsname()->nodename);
> + rpc_clnt_set_nodename(new);
> if (new->cl_auth)
> atomic_inc(&new->cl_auth->au_count);
> atomic_inc(&clnt->cl_count);
>
> --
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Acked-by: Jeff Layton <jlayton@redhat.com>