// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2015-2018 Oracle. All rights reserved.
*
* Support for reverse-direction RPCs on RPC/RDMA (server-side).
*/
#include <linux/sunrpc/svc_rdma.h>
#include "xprt_rdma.h"
#include <trace/events/rpcrdma.h>
/**
* svc_rdma_handle_bc_reply - Process incoming backchannel Reply
* @rqstp: resources for handling the Reply
* @rctxt: Received message
*
*/
void svc_rdma_handle_bc_reply(struct svc_rqst *rqstp,
struct svc_rdma_recv_ctxt *rctxt)
{
struct svc_xprt *sxprt = rqstp->rq_xprt;
struct rpc_xprt *xprt = sxprt->xpt_bc_xprt;
struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
struct xdr_buf *rcvbuf = &rqstp->rq_arg;
struct kvec *dst, *src = &rcvbuf->head[0];
__be32 *rdma_resp = rctxt->rc_recv_buf;
struct rpc_rqst *req;
u32 credits;
spin_lock(&xprt->queue_lock);
req = xprt_lookup_rqst(xprt, *rdma_resp);
if (!req)
goto out_unlock;
dst = &req->rq_private_buf.head[0];
memcpy(&req->rq_private_buf, &req->rq_rcv_buf, sizeof(struct xdr_buf));
if (dst->iov_len < src->iov_len)
goto out_unlock;
memcpy(dst->iov_base, src->iov_base, src->iov_len);
xprt_pin_rqst(req);
spin_unlock(&xprt->queue_lock);
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(&xprt->transport_lock);
xprt->cwnd = credits << RPC_CWNDSHIFT;
spin_unlock(&xprt->transport_lock);
spin_lock(&xprt->queue_lock);
xprt_complete_rqst(req->rq_task, rcvbuf->len);
xprt_unpin_rqst(req);
rcvbuf->len = 0;
out_unlock:
spin_unlock(&xprt->queue_lock);
}
/* Send a reverse-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_send_ctxt *sctxt)
{
struct svc_rdma_pcl empty_pcl;
int ret;
pcl_init(&empty_pcl);
ret = svc_rdma_map_reply_msg(rdma, sctxt, &empty_pcl, &empty_pcl,
&rqst->rq_snd_buf);
if (ret < 0)
return -EIO;
/* 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));
sctxt->sc_send_wr.opcode = IB_WR_SEND;
return svc_rdma_post_send(rdma, sctxt);
}
/* 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(GFP_NOIO | __GFP_NOWARN);
if (!page)
return -ENOMEM;
rqst->rq_buffer = page_address(page);
rqst->rq_rbuffer = kmalloc(rqst->rq_rcvsize, GFP_NOIO | __GFP_NOWARN);
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);
struct svc_rdma_send_ctxt *ctxt;
__be32 *p;
int rc;
ctxt = svc_rdma_send_ctxt_get(rdma);
if (!ctxt)
goto drop_connection;
p = xdr_reserve_space(&ctxt->sc_stream, RPCRDMA_HDRLEN_MIN);
if (!p)
goto put_ctxt;
*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;
rqst->rq_xtime = ktime_get();
rc = svc_rdma_bc_sendto(rdma, rqst, ctxt);
if (rc)
goto put_ctxt;
return 0;
put_ctxt:
svc_rdma_send_ctxt_put(rdma, ctxt);
drop_connection:
return -ENOTCONN;
}
/**
* xprt_rdma_bc_send_request - Send a reverse-direction Call
* @rqst: rpc_rqst containing Call message to be sent
*
* Return values:
* %0 if the message was sent successfully
* %ENOTCONN if the message was not sent
*/
static int xprt_rdma_bc_send_request(struct rpc_rqst *rqst)
{
struct svc_xprt *sxprt = rqst->rq_xprt->bc_xprt;
struct svcxprt_rdma *rdma =
container_of(sxprt, struct svcxprt_rdma, sc_xprt);
int ret;
if (test_bit(XPT_DEAD, &sxprt->xpt_flags))
return -ENOTCONN;
ret = rpcrdma_bc_send_request(rdma, rqst);
if (ret == -ENOTCONN)
svc_xprt_close(sxprt);
return ret;
}
static void
xprt_rdma_bc_close(struct rpc_xprt *xprt)
{
xprt_disconnect_done(xprt);
xprt->cwnd = RPC_CWNDSHIFT;
}
static void
xprt_rdma_bc_put(struct rpc_xprt *xprt)
{
xprt_rdma_free_addresses(xprt);
xprt_free(xprt);
}
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,
.free_slot = xprt_free_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,
.wait_for_reply_request = xprt_wait_for_reply_request_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))
return ERR_PTR(-EBADF);
xprt = xprt_alloc(args->net, sizeof(*new_xprt),
RPCRDMA_MAX_BC_REQUESTS,
RPCRDMA_MAX_BC_REQUESTS);
if (!xprt)
return ERR_PTR(-ENOMEM);
xprt->timeout = &xprt_rdma_bc_timeout;
xprt_set_bound(xprt);
xprt_set_connected(xprt);
xprt->bind_timeout = 0;
xprt->reestablish_timeout = 0;
xprt->idle_timeout = 0;
xprt->prot = XPRT_TRANSPORT_BC_RDMA;
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;
/* Final put for backchannel xprt is in __svc_rdma_free */
xprt_get(xprt);
return xprt;
}
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,
};
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