Re: [PATCH net-next 1/3] SUNRPC: add netns refcount tracker to struct svc_xprt

From: Chuck Lever III <chuck.lever@oracle.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: "David S . Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
	netdev <netdev@vger.kernel.org>,
	Eric Dumazet <edumazet@google.com>
Subject: Re: [PATCH net-next 1/3] SUNRPC: add netns refcount tracker to struct svc_xprt
Date: Thu, 27 Jan 2022 20:25:18 +0000	[thread overview]
Message-ID: <534A0F41-2823-4E29-85E7-D1E8406047F9@oracle.com> (raw)
In-Reply-To: <20220127200937.2157402-2-eric.dumazet@gmail.com>

> On Jan 27, 2022, at 3:09 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> 
> From: Eric Dumazet <edumazet@google.com>
> 
> struct svc_xprt holds a long lived reference to a netns,
> it is worth tracking it.
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>

I haven't followed the requirements for the extended tracking,
but I have no objection to this change.

Acked-by: Chuck Lever <chuck.lever@oracle.com>

> ---
> include/linux/sunrpc/svc_xprt.h | 1 +
> net/sunrpc/svc_xprt.c           | 4 ++--
> 2 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/sunrpc/svc_xprt.h b/include/linux/sunrpc/svc_xprt.h
> index 571f605bc91ef8fa190e7fd5504efb76ec3fa89e..382af90320acc3a7b3817bf66f65fbb15447ae7d 100644
> --- a/include/linux/sunrpc/svc_xprt.h
> +++ b/include/linux/sunrpc/svc_xprt.h
> @@ -88,6 +88,7 @@ struct svc_xprt {
> 	struct list_head	xpt_users;	/* callbacks on free */
> 
> 	struct net		*xpt_net;
> +	netns_tracker		ns_tracker;
> 	const struct cred	*xpt_cred;
> 	struct rpc_xprt		*xpt_bc_xprt;	/* NFSv4.1 backchannel */
> 	struct rpc_xprt_switch	*xpt_bc_xps;	/* NFSv4.1 backchannel */
> diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
> index b21ad79941474685597c9c7c07b862ef7e98ad74..db878e833b672864551bc9ef884a3cd6ca6c2603 100644
> --- a/net/sunrpc/svc_xprt.c
> +++ b/net/sunrpc/svc_xprt.c
> @@ -162,7 +162,7 @@ static void svc_xprt_free(struct kref *kref)
> 	if (test_bit(XPT_CACHE_AUTH, &xprt->xpt_flags))
> 		svcauth_unix_info_release(xprt);
> 	put_cred(xprt->xpt_cred);
> -	put_net(xprt->xpt_net);
> +	put_net_track(xprt->xpt_net, &xprt->ns_tracker);
> 	/* See comment on corresponding get in xs_setup_bc_tcp(): */
> 	if (xprt->xpt_bc_xprt)
> 		xprt_put(xprt->xpt_bc_xprt);
> @@ -198,7 +198,7 @@ void svc_xprt_init(struct net *net, struct svc_xprt_class *xcl,
> 	mutex_init(&xprt->xpt_mutex);
> 	spin_lock_init(&xprt->xpt_lock);
> 	set_bit(XPT_BUSY, &xprt->xpt_flags);
> -	xprt->xpt_net = get_net(net);
> +	xprt->xpt_net = get_net_track(net, &xprt->ns_tracker, GFP_ATOMIC);
> 	strcpy(xprt->xpt_remotebuf, "uninitialized");
> }
> EXPORT_SYMBOL_GPL(svc_xprt_init);
> -- 
> 2.35.0.rc0.227.g00780c9af4-goog
> 

--
Chuck Lever