linux-kernel - Re: [PATCH v2] SUNRPC: Allow one callback request to be received from two sk

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Date:	Sat, 08 Feb 2014 23:14:51 +0400
From:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:	shaobingqing <shaobingqing@...tor.com.cn>,
	trond.myklebust@...marydata.com, bfields@...hat.com,
	davem@...emloft.net
CC:	linux-nfs@...r.kernel.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] SUNRPC: Allow one callback request to be received
 from two sk_buff

Hello.

On 08-02-2014 6:29, shaobingqing wrote:

> In current code, there only one struct rpc_rqst is prealloced. If one
> callback request is received from two sk_buff, the xprt_alloc_bc_request
> would be execute two times with the same transport->xid. The first time
> xprt_alloc_bc_request will alloc one struct rpc_rqst and the TCP_RCV_COPY_DATA
> bit of transport->tcp_flags will not be cleared. The second time
> xprt_alloc_bc_request could not alloc struct rpc_rqst any more and NULL
> pointer will be returned, then xprt_force_disconnect occur. I think one
> callback request can be allowed to be received from two sk_buff.

> Signed-off-by: shaobingqing <shaobingqing@...tor.com.cn>
[...]

> diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
> index cec7b9b..82bfe01 100644
> --- a/include/linux/sunrpc/xprt.h
> +++ b/include/linux/sunrpc/xprt.h
> @@ -211,6 +211,7 @@ struct rpc_xprt {
>   						 * items */
>   	struct list_head	bc_pa_list;	/* List of preallocated
>   						 * backchannel rpc_rqst's */
> +	struct rpc_rqst	*req_first;

    Please align the variable name with the ones above and below.

>   #endif /* CONFIG_SUNRPC_BACKCHANNEL */
>   	struct list_head	recv;
>
[...]
> diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
> index ee03d35..c43dca4 100644
> --- a/net/sunrpc/xprtsock.c
> +++ b/net/sunrpc/xprtsock.c
> @@ -1272,7 +1272,16 @@ static inline int xs_tcp_read_callback(struct rpc_xprt *xprt,
>   				container_of(xprt, struct sock_xprt, xprt);
>   	struct rpc_rqst *req;
>
> -	req = xprt_alloc_bc_request(xprt);
> +	if (xprt->req_first != NULL &&
> +			xprt->req_first->rq_xid == transport->tcp_xid) {

    The continuation line should be aligned right under 'xprt' on the broken 
up line, according to the networking coding style.

> +		req = xprt->req_first;
> +	} else if (xprt->req_first != NULL &&
> +			xprt->req_first->rq_xid != transport->tcp_xid) {

    Same here.

WBR, Sergei

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