/* Send a backwards direction RPC call.
*
* Caller holds the connection's mutex and has already marshaled
* the RPC/RDMA request.
*
* This is similar to svc_rdma_reply, but takes an rpc_rqst
* instead, does not support chunks, and avoids blocking memory
* allocation.
*
* XXX: There is still an opportunity to block in svc_rdma_send()
* if there are no SQ entries to post the Send. This may occur if
* the adapter has a small maximum SQ depth.
*/
static int svc_rdma_bc_sendto(struct svcxprt_rdma *rdma,
struct rpc_rqst *rqst)
{
struct xdr_buf *sndbuf = &rqst->rq_snd_buf;
struct svc_rdma_op_ctxt *ctxt;
struct svc_rdma_req_map *vec;
struct ib_send_wr send_wr;
int ret;
vec = svc_rdma_get_req_map(rdma);
ret = svc_rdma_map_xdr(rdma, sndbuf, vec, false);
if (ret)
goto out_err;
ret = svc_rdma_repost_recv(rdma, GFP_NOIO);
if (ret)
goto out_err;
ctxt = svc_rdma_get_context(rdma);
ctxt->pages[0] = virt_to_page(rqst->rq_buffer);
ctxt->count = 1;
ctxt->direction = DMA_TO_DEVICE;
ctxt->sge[0].lkey = rdma->sc_pd->local_dma_lkey;
ctxt->sge[0].length = sndbuf->len;
ctxt->sge[0].addr =
ib_dma_map_page(rdma->sc_cm_id->device, ctxt->pages[0], 0,
sndbuf->len, DMA_TO_DEVICE);
if (ib_dma_mapping_error(rdma->sc_cm_id->device, ctxt->sge[0].addr)) {
ret = -EIO;
goto out_unmap;
}
svc_rdma_count_mappings(rdma, ctxt);
memset(&send_wr, 0, sizeof(send_wr));
ctxt->cqe.done = svc_rdma_wc_send;
send_wr.wr_cqe = &ctxt->cqe;
send_wr.sg_list = ctxt->sge;
send_wr.num_sge = 1;
send_wr.opcode = IB_WR_SEND;
send_wr.send_flags = IB_SEND_SIGNALED;
ret = svc_rdma_send(rdma, &send_wr);
if (ret) {
ret = -EIO;
goto out_unmap;
}
out_err:
svc_rdma_put_req_map(rdma, vec);
dprintk("svcrdma: %s returns %d\n", __func__, ret);
return ret;
out_unmap:
svc_rdma_unmap_dma(ctxt);
svc_rdma_put_context(ctxt, 1);
goto out_err;
}
static int
svc_rdma_post_recv(struct svcxprt_rdma *xprt)
{
struct ib_recv_wr recv_wr, *bad_recv_wr;
struct svc_rdma_op_ctxt *ctxt;
struct page *page;
dma_addr_t pa;
int sge_no;
int buflen;
int ret;
ctxt = svc_rdma_get_context(xprt);
buflen = 0;
ctxt->direction = DMA_FROM_DEVICE;
ctxt->cqe.done = svc_rdma_wc_receive;
for (sge_no = 0; buflen < xprt->sc_max_req_size; sge_no++) {
if (sge_no >= xprt->sc_max_sge) {
pr_err("svcrdma: Too many sges (%d)\n", sge_no);
goto err_put_ctxt;
}
page = alloc_page(GFP_KERNEL);
if (!page)
goto err_put_ctxt;
ctxt->pages[sge_no] = page;
pa = ib_dma_map_page(xprt->sc_cm_id->device,
page, 0, PAGE_SIZE,
DMA_FROM_DEVICE);
if (ib_dma_mapping_error(xprt->sc_cm_id->device, pa))
goto err_put_ctxt;
svc_rdma_count_mappings(xprt, ctxt);
ctxt->sge[sge_no].addr = pa;
ctxt->sge[sge_no].length = PAGE_SIZE;
ctxt->sge[sge_no].lkey = xprt->sc_pd->local_dma_lkey;
ctxt->count = sge_no + 1;
buflen += PAGE_SIZE;
}
recv_wr.next = NULL;
recv_wr.sg_list = &ctxt->sge[0];
recv_wr.num_sge = ctxt->count;
recv_wr.wr_cqe = &ctxt->cqe;
svc_xprt_get(&xprt->sc_xprt);
ret = ib_post_recv(xprt->sc_qp, &recv_wr, &bad_recv_wr);
if (ret) {
svc_rdma_unmap_dma(ctxt);
svc_rdma_put_context(ctxt, 1);
svc_xprt_put(&xprt->sc_xprt);
}
return ret;
err_put_ctxt:
svc_rdma_unmap_dma(ctxt);
svc_rdma_put_context(ctxt, 1);
return -ENOMEM;
}
