Re: [PATCH 2/4] nfs: remove sv_bc_enabled using in svc_is_backchannel()

[Jeff Layton <jlayton@kernel.org>]

On Mon, 2018-12-17 at 19:25 +0300, Vasily Averin wrote:
> serv->sv_bc_xprt cannot be used as pointer,
> serv is global structure, but sv_bc_xprt is assigned per-netnamespace
> 
> The only user of this field is svc_is_backchannel() where it is used
> not as pointer but as mark of backchannel-compatible servers. 
> 
> Convert netns-unsafe xprt pointer to simple boolean mark,
> Hope it helps to prevent misuse of sv_bc_xpr in future. 
> 
> Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
> ---
>  include/linux/sunrpc/bc_xprt.h           | 10 ++++------
>  include/linux/sunrpc/svc.h               |  2 +-
>  net/sunrpc/svcsock.c                     |  2 +-
>  net/sunrpc/xprtrdma/svc_rdma_transport.c |  2 +-
>  4 files changed, 7 insertions(+), 9 deletions(-)
> 
> diff --git a/include/linux/sunrpc/bc_xprt.h b/include/linux/sunrpc/bc_xprt.h
> index 28721cf73ec3..4e8c773d02be 100644
> --- a/include/linux/sunrpc/bc_xprt.h
> +++ b/include/linux/sunrpc/bc_xprt.h
> @@ -47,11 +47,9 @@ void xprt_free_bc_rqst(struct rpc_rqst *req);
>  /*
>   * Determine if a shared backchannel is in use
>   */
> -static inline int svc_is_backchannel(const struct svc_rqst *rqstp)
> +static inline bool svc_is_backchannel(const struct svc_rqst *rqstp)
>  {
> -	if (rqstp->rq_server->sv_bc_xprt)
> -		return 1;
> -	return 0;
> +	return rqstp->rq_server->sv_bc_enabled;
>  }
>  #else /* CONFIG_SUNRPC_BACKCHANNEL */
>  static inline int xprt_setup_backchannel(struct rpc_xprt *xprt,
> @@ -60,9 +58,9 @@ static inline int xprt_setup_backchannel(struct rpc_xprt *xprt,
>  	return 0;
>  }
>  
> -static inline int svc_is_backchannel(const struct svc_rqst *rqstp)
> +static inline bool svc_is_backchannel(const struct svc_rqst *rqstp)
>  {
> -	return 0;
> +	return false;
>  }
>  
>  static inline void xprt_free_bc_request(struct rpc_rqst *req)
> diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
> index 73e130a840ce..bf21609160c1 100644
> --- a/include/linux/sunrpc/svc.h
> +++ b/include/linux/sunrpc/svc.h
> @@ -109,7 +109,7 @@ struct svc_serv {
>  	spinlock_t		sv_cb_lock;	/* protects the svc_cb_list */
>  	wait_queue_head_t	sv_cb_waitq;	/* sleep here if there are no
>  						 * entries in the svc_cb_list */
> -	struct svc_xprt		*sv_bc_xprt;	/* callback on fore channel */
> +	bool			sv_bc_enabled;	/* server uses backchannel */
>  #endif /* CONFIG_SUNRPC_BACKCHANNEL */
>  };
>  
> diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
> index 986f3ed7d1a2..5a6b3ba555c7 100644
> --- a/net/sunrpc/svcsock.c
> +++ b/net/sunrpc/svcsock.c
> @@ -1623,7 +1623,7 @@ static struct svc_xprt *svc_bc_create_socket(struct svc_serv *serv,
>  	svc_xprt_init(net, &svc_tcp_bc_class, xprt, serv);
>  	set_bit(XPT_CONG_CTRL, &svsk->sk_xprt.xpt_flags);
>  
> -	serv->sv_bc_xprt = xprt;
> +	serv->sv_bc_enabled = true;
>  
>  	return xprt;
>  }
> diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c b/net/sunrpc/xprtrdma/svc_rdma_transport.c
> index 2f7ec8912f49..88694048d5c0 100644
> --- a/net/sunrpc/xprtrdma/svc_rdma_transport.c
> +++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c
> @@ -136,7 +136,7 @@ static struct svc_xprt *svc_rdma_bc_create(struct svc_serv *serv,
>  
>  	svc_xprt_init(net, &svc_rdma_bc_class, xprt, serv);
>  	set_bit(XPT_CONG_CTRL, &xprt->xpt_flags);
> -	serv->sv_bc_xprt = xprt;
> +	serv->sv_bc_enabled = true;
>  
>  	dprintk("svcrdma: %s(%p)\n", __func__, xprt);
>  	return xprt;

Reviewed-by: Jeff Layton <jlayton@kernel.org>