Hi Sagi- Thanks for the review.
On Jan 11, 2015, at 12:37 PM, Sagi Grimberg <[email protected]> wrote: > On 1/9/2015 9:22 PM, Chuck Lever wrote: >> 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. > > Would it make more sense to add another pointer assigned at req > initialization (maybe in the RDMA request context) instead of hard > coding this assumption? I may be completely wrong here though... I considered this. I couldn’t find an appropriate place to add such a pointer. I think that’s why xdr_start() was there in the first place: there is no convenient place to save a pointer to the request’s RDMA header. Bruce might have other thoughts about this. >> Signed-off-by: Chuck Lever <[email protected]> >> --- >> >> net/sunrpc/xprtrdma/svc_rdma_sendto.c | 18 ++++-------------- >> 1 files changed, 4 insertions(+), 14 deletions(-) >> >> diff --git a/net/sunrpc/xprtrdma/svc_rdma_sendto.c >> b/net/sunrpc/xprtrdma/svc_rdma_sendto.c >> index 7d79897..7de33d1 100644 >> --- a/net/sunrpc/xprtrdma/svc_rdma_sendto.c >> +++ b/net/sunrpc/xprtrdma/svc_rdma_sendto.c >> @@ -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); >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-rdma" in >> the body of a message to [email protected] >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> > > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Chuck Lever chuck[dot]lever[at]oracle[dot]com -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
