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Commit e5523bd2 authored by Chuck Lever's avatar Chuck Lever Committed by J. Bruce Fields
Browse files

svcrdma: Find rmsgp more reliably 



xdr_start() can return the wrong rmsgp address if an assumption
about how the xdr_buf was constructed changes.  When it gets it
wrong, the client receives a reply that has gibberish in the
RPC/RDMA header, preventing it from matching a waiting RPC request.

Instead, make (and document) just one assumption: that the RDMA
header for the client's RPC call is at the start of the first page
in rq_pages.

Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
Reviewed-by: default avatarSteve Wise <swise@opengridcomputing.com>
Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
parent 3fe04ee9

net/sunrpc/xprtrdma/svc_rdma_sendto.c

+4 −14
Original line number Diff line number Diff line
@@ -483,18 +483,6 @@ void svc_rdma_prep_reply_hdr(struct svc_rqst *rqstp) 
{

}



/*

 * Return the start of an xdr buffer.

 */

static void *xdr_start(struct xdr_buf *xdr)

{

	return xdr->head[0].iov_base -

		(xdr->len -

		 xdr->page_len -

		 xdr->tail[0].iov_len -

		 xdr->head[0].iov_len);

}



int svc_rdma_sendto(struct svc_rqst *rqstp)

{

	struct svc_xprt *xprt = rqstp->rq_xprt;
@@ -512,8 +500,10 @@ int svc_rdma_sendto(struct svc_rqst *rqstp) 


	dprintk("svcrdma: sending response for rqstp=%p\n", rqstp);



	/* Get the RDMA request header. */

	rdma_argp = xdr_start(&rqstp->rq_arg);

	/* Get the RDMA request header. The receive logic always

	 * places this at the start of page 0.

	 */

	rdma_argp = page_address(rqstp->rq_pages[0]);



	/* Build an req vec for the XDR */

	ctxt = svc_rdma_get_context(rdma);