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

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Message-ID: <20120813073505.7870ef21@corrin.poochiereds.net>
Date:	Mon, 13 Aug 2012 07:35:05 -0400
From:	Jeff Layton <jlayton@...chiereds.net>
To:	Stanislav Kinsbursky <skinsbursky@...allels.com>
Cc:	Trond.Myklebust@...app.com, bfields@...ldses.org,
	linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org,
	devel@...nvz.org
Subject: Re: [PATCH] SUNRPC: check current nsproxy before set of node name
 on client creation

On Mon, 13 Aug 2012 15:21:56 +0400
Stanislav Kinsbursky <skinsbursky@...allels.com> wrote:

> When child reaper exits, it can destroy mount namespace it belong 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@...allels.com>
> ---
>  net/sunrpc/clnt.c |   14 ++++++++++++--
>  1 files changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
> index 9a9676e..28ac940 100644
> --- a/net/sunrpc/clnt.c
> +++ b/net/sunrpc/clnt.c
> @@ -279,6 +279,16 @@ void rpc_clients_notifier_unregister(void)
>  
>  static void rpc_clnt_set_nodename(struct rpc_clnt *clnt, const char *nodename)

Don't you need to change the prototype of the function here too?

>  {
> +	const char *nodename;
> +
> +	/*
> +	 * We have to protect against dying chilp reaper, which has released

	nit: "dying child reaper" ?

> +	 * it's nsproxy already and is trying to destroy mount namespace.

	nit: "its"

> +	 */
> +	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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-- 
Jeff Layton <jlayton@...chiereds.net>
--
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