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 <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
Chuck Lever 2017-04-09 13:06:49 -04:00 committed by J. Bruce Fields
parent 4757d90b15
commit f5821c76b2
3 changed files with 33 additions and 20 deletions

View File

@ -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 */

View File

@ -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)

View File

@ -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)