Re: [PATCH v1 02/22] SUNRPC: Refactor rpc_xdr_buf_init()

[Trond Myklebust <trondmy-7I+n7zu2hftEKMMhf/gKZA@public.gmane.org>]

> On Aug 15, 2016, at 16:50, Chuck Lever <chuck.lever-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org> wrote:
> 
> Clean up: there is some XDR initialization logic that is commoon
> to the forward channel and backchannel. Move it to an XDR header
> so it can be shared.
> 
> rpc_rqst::rq_buffer points to a buffer containing big-endian data.
> Update its annotation as part of the clean up.
> 
> Signed-off-by: Chuck Lever <chuck.lever-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
> ---
> include/linux/sunrpc/xdr.h        |   10 ++++++++++
> include/linux/sunrpc/xprt.h       |    2 +-
> net/sunrpc/backchannel_rqst.c     |    8 +-------
> net/sunrpc/clnt.c                 |   24 ++++++------------------
> net/sunrpc/xprtrdma/backchannel.c |   12 +-----------
> 5 files changed, 19 insertions(+), 37 deletions(-)
> 
> diff --git a/include/linux/sunrpc/xdr.h b/include/linux/sunrpc/xdr.h
> index 70c6b92..551569c 100644
> --- a/include/linux/sunrpc/xdr.h
> +++ b/include/linux/sunrpc/xdr.h
> @@ -67,6 +67,16 @@ struct xdr_buf {
> 			len;		/* Length of XDR encoded message */
> };
> 
> +static inline void
> +xdr_buf_init(struct xdr_buf *buf, __be32 *start, size_t len)
> +{
> +	memset(buf, 0, sizeof(*buf));

Can we please leave this as it was. There is no need to zero out unused fields such as the pages pointer, the tail iov_base, etc.

> +
> +	buf->head[0].iov_base = start;
> +	buf->head[0].iov_len = len;
> +	buf->buflen = len;
> +}
> +
> /*
>  * pre-xdr'ed macros.
>  */
> diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
> index a16070d..559dad3 100644
> --- a/include/linux/sunrpc/xprt.h
> +++ b/include/linux/sunrpc/xprt.h
> @@ -83,7 +83,7 @@ struct rpc_rqst {
> 	void (*rq_release_snd_buf)(struct rpc_rqst *); /* release rq_enc_pages */
> 	struct list_head	rq_list;
> 
> -	__u32 *			rq_buffer;	/* XDR encode buffer */
> +	__be32			*rq_buffer;	/* Call XDR encode buffer */

If changing it, why not make it a void* ? Nothing should ever be touching the contents of this buffer directly.

> 	size_t			rq_callsize,
> 				rq_rcvsize;
> 	size_t			rq_xmit_bytes_sent;	/* total bytes sent */
> diff --git a/net/sunrpc/backchannel_rqst.c b/net/sunrpc/backchannel_rqst.c
> index 229956b..ac701c2 100644
> --- a/net/sunrpc/backchannel_rqst.c
> +++ b/net/sunrpc/backchannel_rqst.c
> @@ -76,13 +76,7 @@ static int xprt_alloc_xdr_buf(struct xdr_buf *buf, gfp_t gfp_flags)
> 	page = alloc_page(gfp_flags);
> 	if (page == NULL)
> 		return -ENOMEM;
> -	buf->head[0].iov_base = page_address(page);
> -	buf->head[0].iov_len = PAGE_SIZE;
> -	buf->tail[0].iov_base = NULL;
> -	buf->tail[0].iov_len = 0;
> -	buf->page_len = 0;
> -	buf->len = 0;
> -	buf->buflen = PAGE_SIZE;
> +	xdr_buf_init(buf, page_address(page), PAGE_SIZE);
> 	return 0;
> }
> 
> diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
> index 7f79fb7..0e75369 100644
> --- a/net/sunrpc/clnt.c
> +++ b/net/sunrpc/clnt.c
> @@ -1748,18 +1748,6 @@ rpc_task_force_reencode(struct rpc_task *task)
> 	task->tk_rqstp->rq_bytes_sent = 0;
> }
> 
> -static inline void
> -rpc_xdr_buf_init(struct xdr_buf *buf, void *start, size_t len)
> -{
> -	buf->head[0].iov_base = start;
> -	buf->head[0].iov_len = len;
> -	buf->tail[0].iov_len = 0;
> -	buf->page_len = 0;
> -	buf->flags = 0;
> -	buf->len = 0;
> -	buf->buflen = len;
> -}
> -
> /*
>  * 3.	Encode arguments of an RPC call
>  */
> @@ -1772,12 +1760,12 @@ rpc_xdr_encode(struct rpc_task *task)
> 
> 	dprint_status(task);
> 
> -	rpc_xdr_buf_init(&req->rq_snd_buf,
> -			 req->rq_buffer,
> -			 req->rq_callsize);
> -	rpc_xdr_buf_init(&req->rq_rcv_buf,
> -			 (char *)req->rq_buffer + req->rq_callsize,
> -			 req->rq_rcvsize);
> +	xdr_buf_init(&req->rq_snd_buf,
> +		     req->rq_buffer,
> +		     req->rq_callsize);
> +	xdr_buf_init(&req->rq_rcv_buf,
> +		     (__be32 *)((char *)req->rq_buffer + req->rq_callsize),
> +		     req->rq_rcvsize);
> 
> 	p = rpc_encode_header(task);
> 	if (p == NULL) {
> diff --git a/net/sunrpc/xprtrdma/backchannel.c b/net/sunrpc/xprtrdma/backchannel.c
> index 5f60ab2..d3cfaf2 100644
> --- a/net/sunrpc/xprtrdma/backchannel.c
> +++ b/net/sunrpc/xprtrdma/backchannel.c
> @@ -38,7 +38,6 @@ static int rpcrdma_bc_setup_rqst(struct rpcrdma_xprt *r_xprt,
> 	struct rpcrdma_ia *ia = &r_xprt->rx_ia;
> 	struct rpcrdma_regbuf *rb;
> 	struct rpcrdma_req *req;
> -	struct xdr_buf *buf;
> 	size_t size;
> 
> 	req = rpcrdma_create_req(r_xprt);
> @@ -60,16 +59,7 @@ static int rpcrdma_bc_setup_rqst(struct rpcrdma_xprt *r_xprt,
> 	req->rl_sendbuf = rb;
> 	/* so that rpcr_to_rdmar works when receiving a request */
> 	rqst->rq_buffer = (void *)req->rl_sendbuf->rg_base;
> -
> -	buf = &rqst->rq_snd_buf;
> -	buf->head[0].iov_base = rqst->rq_buffer;
> -	buf->head[0].iov_len = 0;
> -	buf->tail[0].iov_base = NULL;
> -	buf->tail[0].iov_len = 0;
> -	buf->page_len = 0;
> -	buf->len = 0;
> -	buf->buflen = size;
> -
> +	xdr_buf_init(&rqst->rq_snd_buf, rqst->rq_buffer, size);
> 	return 0;
> 
> out_fail:
> 
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