From f5821c76b2c9c2fb98b276c0bf6a101bfe9050a3 Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Sun, 9 Apr 2017 13:06:49 -0400 Subject: [PATCH] svcrdma: Clean up RPC-over-RDMA backchannel reply processing Replace C structure-based XDR decoding with pointer arithmetic. Pointer arithmetic is considered more portable. Signed-off-by: Chuck Lever Signed-off-by: J. Bruce Fields --- include/linux/sunrpc/svc_rdma.h | 2 +- net/sunrpc/xprtrdma/svc_rdma_backchannel.c | 18 +++++++++--- net/sunrpc/xprtrdma/svc_rdma_recvfrom.c | 33 ++++++++++++---------- 3 files changed, 33 insertions(+), 20 deletions(-) diff --git a/include/linux/sunrpc/svc_rdma.h b/include/linux/sunrpc/svc_rdma.h index a770d200f607..44d642bbfce6 100644 --- a/include/linux/sunrpc/svc_rdma.h +++ b/include/linux/sunrpc/svc_rdma.h @@ -204,7 +204,7 @@ static inline void svc_rdma_count_mappings(struct svcxprt_rdma *rdma, /* svc_rdma_backchannel.c */ extern int svc_rdma_handle_bc_reply(struct rpc_xprt *xprt, - struct rpcrdma_msg *rmsgp, + __be32 *rdma_resp, struct xdr_buf *rcvbuf); /* svc_rdma_marshal.c */ diff --git a/net/sunrpc/xprtrdma/svc_rdma_backchannel.c b/net/sunrpc/xprtrdma/svc_rdma_backchannel.c index bf185b79c98f..c676ed0efb5a 100644 --- a/net/sunrpc/xprtrdma/svc_rdma_backchannel.c +++ b/net/sunrpc/xprtrdma/svc_rdma_backchannel.c @@ -12,7 +12,17 @@ #undef SVCRDMA_BACKCHANNEL_DEBUG -int svc_rdma_handle_bc_reply(struct rpc_xprt *xprt, struct rpcrdma_msg *rmsgp, +/** + * svc_rdma_handle_bc_reply - Process incoming backchannel reply + * @xprt: controlling backchannel transport + * @rdma_resp: pointer to incoming transport header + * @rcvbuf: XDR buffer into which to decode the reply + * + * Returns: + * %0 if @rcvbuf is filled in, xprt_complete_rqst called, + * %-EAGAIN if server should call ->recvfrom again. + */ +int svc_rdma_handle_bc_reply(struct rpc_xprt *xprt, __be32 *rdma_resp, struct xdr_buf *rcvbuf) { struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); @@ -27,13 +37,13 @@ int svc_rdma_handle_bc_reply(struct rpc_xprt *xprt, struct rpcrdma_msg *rmsgp, p = (__be32 *)src->iov_base; len = src->iov_len; - xid = rmsgp->rm_xid; + xid = *rdma_resp; #ifdef SVCRDMA_BACKCHANNEL_DEBUG pr_info("%s: xid=%08x, length=%zu\n", __func__, be32_to_cpu(xid), len); pr_info("%s: RPC/RDMA: %*ph\n", - __func__, (int)RPCRDMA_HDRLEN_MIN, rmsgp); + __func__, (int)RPCRDMA_HDRLEN_MIN, rdma_resp); pr_info("%s: RPC: %*ph\n", __func__, (int)len, p); #endif @@ -53,7 +63,7 @@ int svc_rdma_handle_bc_reply(struct rpc_xprt *xprt, struct rpcrdma_msg *rmsgp, goto out_unlock; memcpy(dst->iov_base, p, len); - credits = be32_to_cpu(rmsgp->rm_credit); + credits = be32_to_cpup(rdma_resp + 2); if (credits == 0) credits = 1; /* don't deadlock */ else if (credits > r_xprt->rx_buf.rb_bc_max_requests) diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c index 7435cb666f42..27a99bf5b1a6 100644 --- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c @@ -613,28 +613,30 @@ static void svc_rdma_send_error(struct svcxprt_rdma *xprt, * the RPC/RDMA header small and fixed in size, so it is * straightforward to check the RPC header's direction field. */ -static bool -svc_rdma_is_backchannel_reply(struct svc_xprt *xprt, struct rpcrdma_msg *rmsgp) +static bool svc_rdma_is_backchannel_reply(struct svc_xprt *xprt, + __be32 *rdma_resp) { - __be32 *p = (__be32 *)rmsgp; + __be32 *p; if (!xprt->xpt_bc_xprt) return false; - if (rmsgp->rm_type != rdma_msg) - return false; - if (rmsgp->rm_body.rm_chunks[0] != xdr_zero) - return false; - if (rmsgp->rm_body.rm_chunks[1] != xdr_zero) - return false; - if (rmsgp->rm_body.rm_chunks[2] != xdr_zero) + p = rdma_resp + 3; + if (*p++ != rdma_msg) return false; - /* sanity */ - if (p[7] != rmsgp->rm_xid) + if (*p++ != xdr_zero) + return false; + if (*p++ != xdr_zero) + return false; + if (*p++ != xdr_zero) + return false; + + /* XID sanity */ + if (*p++ != *rdma_resp) return false; /* call direction */ - if (p[8] == cpu_to_be32(RPC_CALL)) + if (*p == cpu_to_be32(RPC_CALL)) return false; return true; @@ -700,8 +702,9 @@ int svc_rdma_recvfrom(struct svc_rqst *rqstp) goto out_drop; rqstp->rq_xprt_hlen = ret; - if (svc_rdma_is_backchannel_reply(xprt, rmsgp)) { - ret = svc_rdma_handle_bc_reply(xprt->xpt_bc_xprt, rmsgp, + if (svc_rdma_is_backchannel_reply(xprt, &rmsgp->rm_xid)) { + ret = svc_rdma_handle_bc_reply(xprt->xpt_bc_xprt, + &rmsgp->rm_xid, &rqstp->rq_arg); svc_rdma_put_context(ctxt, 0); if (ret)