// SPDX-License-Identifier: GPL-2.0 /* * Copyright (c) 2015 Oracle. All rights reserved. * * Support for backward direction RPCs on RPC/RDMA (server-side). */ #include <linux/module.h> #include <linux/sunrpc/svc_rdma.h> #include "xprt_rdma.h" #define RPCDBG_FACILITY RPCDBG_SVCXPRT #undef SVCRDMA_BACKCHANNEL_DEBUG /** * 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); struct kvec *dst, *src = &rcvbuf->head[0]; struct rpc_rqst *req; unsigned long cwnd; u32 credits; size_t len; __be32 xid; __be32 *p; int ret; p = (__be32 *)src->iov_base; len = src->iov_len; 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, rdma_resp); pr_info("%s: RPC: %*ph\n", __func__, (int)len, p); #endif ret = -EAGAIN; if (src->iov_len < 24) goto out_shortreply; spin_lock(&xprt->recv_lock); req = xprt_lookup_rqst(xprt, xid); if (!req) goto out_notfound; dst = &req->rq_private_buf.head[0]; memcpy(&req->rq_private_buf, &req->rq_rcv_buf, sizeof(struct xdr_buf)); if (dst->iov_len < len) goto out_unlock; memcpy(dst->iov_base, p, len); 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) credits = r_xprt->rx_buf.rb_bc_max_requests; spin_lock_bh(&xprt->transport_lock); cwnd = xprt->cwnd; xprt->cwnd = credits << RPC_CWNDSHIFT; if (xprt->cwnd > cwnd) xprt_release_rqst_cong(req->rq_task); spin_unlock_bh(&xprt->transport_lock); ret = 0; xprt_complete_rqst(req->rq_task, rcvbuf->len); rcvbuf->len = 0; out_unlock: spin_unlock(&xprt->recv_lock); out: return ret; out_shortreply: dprintk("svcrdma: short bc reply: xprt=%p, len=%zu\n", xprt, src->iov_len); goto out; out_notfound: dprintk("svcrdma: unrecognized bc reply: xprt=%p, xid=%08x\n", xprt, be32_to_cpu(xid)); goto out_unlock; } /* 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_send_reply_msg, but takes a struct * 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 svc_rdma_op_ctxt *ctxt; int ret; ctxt = svc_rdma_get_context(rdma); /* rpcrdma_bc_send_request builds the transport header and * the backchannel RPC message in the same buffer. Thus only * one SGE is needed to send both. */ ret = svc_rdma_map_reply_hdr(rdma, ctxt, rqst->rq_buffer, rqst->rq_snd_buf.len); if (ret < 0) goto out_err; /* Bump page refcnt so Send completion doesn't release * the rq_buffer before all retransmits are complete. */ get_page(virt_to_page(rqst->rq_buffer)); ret = svc_rdma_post_send_wr(rdma, ctxt, 1, 0); if (ret) goto out_unmap; out_err: dprintk("svcrdma: %s returns %d\n", __func__, ret); return ret; out_unmap: svc_rdma_unmap_dma(ctxt); svc_rdma_put_context(ctxt, 1); ret = -EIO; goto out_err; } /* Server-side transport endpoint wants a whole page for its send * buffer. The client RPC code constructs the RPC header in this * buffer before it invokes ->send_request. */ static int xprt_rdma_bc_allocate(struct rpc_task *task) { struct rpc_rqst *rqst = task->tk_rqstp; size_t size = rqst->rq_callsize; struct page *page; if (size > PAGE_SIZE) { WARN_ONCE(1, "svcrdma: large bc buffer request (size %zu)\n", size); return -EINVAL; } page = alloc_page(RPCRDMA_DEF_GFP); if (!page) return -ENOMEM; rqst->rq_buffer = page_address(page); rqst->rq_rbuffer = kmalloc(rqst->rq_rcvsize, RPCRDMA_DEF_GFP); if (!rqst->rq_rbuffer) { put_page(page); return -ENOMEM; } return 0; } static void xprt_rdma_bc_free(struct rpc_task *task) { struct rpc_rqst *rqst = task->tk_rqstp; put_page(virt_to_page(rqst->rq_buffer)); kfree(rqst->rq_rbuffer); } static int rpcrdma_bc_send_request(struct svcxprt_rdma *rdma, struct rpc_rqst *rqst) { struct rpc_xprt *xprt = rqst->rq_xprt; struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); __be32 *p; int rc; /* Space in the send buffer for an RPC/RDMA header is reserved * via xprt->tsh_size. */ p = rqst->rq_buffer; *p++ = rqst->rq_xid; *p++ = rpcrdma_version; *p++ = cpu_to_be32(r_xprt->rx_buf.rb_bc_max_requests); *p++ = rdma_msg; *p++ = xdr_zero; *p++ = xdr_zero; *p = xdr_zero; #ifdef SVCRDMA_BACKCHANNEL_DEBUG pr_info("%s: %*ph\n", __func__, 64, rqst->rq_buffer); #endif rc = svc_rdma_bc_sendto(rdma, rqst); if (rc) goto drop_connection; return rc; drop_connection: dprintk("svcrdma: failed to send bc call\n"); xprt_disconnect_done(xprt); return -ENOTCONN; } /* Send an RPC call on the passive end of a transport * connection. */ static int xprt_rdma_bc_send_request(struct rpc_task *task) { struct rpc_rqst *rqst = task->tk_rqstp; struct svc_xprt *sxprt = rqst->rq_xprt->bc_xprt; struct svcxprt_rdma *rdma; int ret; dprintk("svcrdma: sending bc call with xid: %08x\n", be32_to_cpu(rqst->rq_xid)); if (!mutex_trylock(&sxprt->xpt_mutex)) { rpc_sleep_on(&sxprt->xpt_bc_pending, task, NULL); if (!mutex_trylock(&sxprt->xpt_mutex)) return -EAGAIN; rpc_wake_up_queued_task(&sxprt->xpt_bc_pending, task); } ret = -ENOTCONN; rdma = container_of(sxprt, struct svcxprt_rdma, sc_xprt); if (!test_bit(XPT_DEAD, &sxprt->xpt_flags)) ret = rpcrdma_bc_send_request(rdma, rqst); mutex_unlock(&sxprt->xpt_mutex); if (ret < 0) return ret; return 0; } static void xprt_rdma_bc_close(struct rpc_xprt *xprt) { dprintk("svcrdma: %s: xprt %p\n", __func__, xprt); } static void xprt_rdma_bc_put(struct rpc_xprt *xprt) { dprintk("svcrdma: %s: xprt %p\n", __func__, xprt); xprt_free(xprt); module_put(THIS_MODULE); } static const struct rpc_xprt_ops xprt_rdma_bc_procs = { .reserve_xprt = xprt_reserve_xprt_cong, .release_xprt = xprt_release_xprt_cong, .alloc_slot = xprt_alloc_slot, .release_request = xprt_release_rqst_cong, .buf_alloc = xprt_rdma_bc_allocate, .buf_free = xprt_rdma_bc_free, .send_request = xprt_rdma_bc_send_request, .set_retrans_timeout = xprt_set_retrans_timeout_def, .close = xprt_rdma_bc_close, .destroy = xprt_rdma_bc_put, .print_stats = xprt_rdma_print_stats }; static const struct rpc_timeout xprt_rdma_bc_timeout = { .to_initval = 60 * HZ, .to_maxval = 60 * HZ, }; /* It shouldn't matter if the number of backchannel session slots * doesn't match the number of RPC/RDMA credits. That just means * one or the other will have extra slots that aren't used. */ static struct rpc_xprt * xprt_setup_rdma_bc(struct xprt_create *args) { struct rpc_xprt *xprt; struct rpcrdma_xprt *new_xprt; if (args->addrlen > sizeof(xprt->addr)) { dprintk("RPC: %s: address too large\n", __func__); return ERR_PTR(-EBADF); } xprt = xprt_alloc(args->net, sizeof(*new_xprt), RPCRDMA_MAX_BC_REQUESTS, RPCRDMA_MAX_BC_REQUESTS); if (!xprt) { dprintk("RPC: %s: couldn't allocate rpc_xprt\n", __func__); return ERR_PTR(-ENOMEM); } xprt->timeout = &xprt_rdma_bc_timeout; xprt_set_bound(xprt); xprt_set_connected(xprt); xprt->bind_timeout = RPCRDMA_BIND_TO; xprt->reestablish_timeout = RPCRDMA_INIT_REEST_TO; xprt->idle_timeout = RPCRDMA_IDLE_DISC_TO; xprt->prot = XPRT_TRANSPORT_BC_RDMA; xprt->tsh_size = RPCRDMA_HDRLEN_MIN / sizeof(__be32); xprt->ops = &xprt_rdma_bc_procs; memcpy(&xprt->addr, args->dstaddr, args->addrlen); xprt->addrlen = args->addrlen; xprt_rdma_format_addresses(xprt, (struct sockaddr *)&xprt->addr); xprt->resvport = 0; xprt->max_payload = xprt_rdma_max_inline_read; new_xprt = rpcx_to_rdmax(xprt); new_xprt->rx_buf.rb_bc_max_requests = xprt->max_reqs; xprt_get(xprt); args->bc_xprt->xpt_bc_xprt = xprt; xprt->bc_xprt = args->bc_xprt; if (!try_module_get(THIS_MODULE)) goto out_fail; /* Final put for backchannel xprt is in __svc_rdma_free */ xprt_get(xprt); return xprt; out_fail: xprt_rdma_free_addresses(xprt); args->bc_xprt->xpt_bc_xprt = NULL; args->bc_xprt->xpt_bc_xps = NULL; xprt_put(xprt); xprt_free(xprt); return ERR_PTR(-EINVAL); } struct xprt_class xprt_rdma_bc = { .list = LIST_HEAD_INIT(xprt_rdma_bc.list), .name = "rdma backchannel", .owner = THIS_MODULE, .ident = XPRT_TRANSPORT_BC_RDMA, .setup = xprt_setup_rdma_bc, };