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>
diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
index 7435cb6..27a99bf 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)