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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2015-2018 Oracle. All rights reserved.
*
* Support for backward direction RPCs on RPC/RDMA (server-side).
*/
#include <linux/sunrpc/svc_rdma.h>
#include "xprt_rdma.h"
#include <trace/events/rpcrdma.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;
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->queue_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);
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);
ret = 0;
xprt_complete_rqst(req->rq_task, rcvbuf->len);
xprt_unpin_rqst(req);
rcvbuf->len = 0;
out_unlock:
spin_unlock(&xprt->queue_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_send_ctxt *ctxt)
{
int ret;
ret = svc_rdma_map_reply_msg(rdma, ctxt, &rqst->rq_snd_buf, NULL);
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));
ctxt->sc_send_wr.opcode = IB_WR_SEND;
return svc_rdma_send(rdma, &ctxt->sc_send_wr);
}
/* 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);
struct svc_rdma_send_ctxt *ctxt;
__be32 *p;
int rc;
ctxt = svc_rdma_send_ctxt_get(rdma);
if (!ctxt)
goto drop_connection;
p = ctxt->sc_xprt_buf;
*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;
svc_rdma_sync_reply_hdr(rdma, ctxt, RPCRDMA_HDRLEN_MIN);
#ifdef SVCRDMA_BACKCHANNEL_DEBUG
pr_info("%s: %*ph\n", __func__, 64, rqst->rq_buffer);
#endif
rc = svc_rdma_bc_sendto(rdma, rqst, ctxt);
if (rc) {
svc_rdma_send_ctxt_put(rdma, ctxt);
goto drop_connection;
}
return 0;
drop_connection:
dprintk("svcrdma: failed to send bc call\n");
return -ENOTCONN;
}
/* Send an RPC call on the passive end of a transport
* connection.
*/
static int
xprt_rdma_bc_send_request(struct rpc_rqst *rqst)
{
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));
mutex_lock(&sxprt->xpt_mutex);
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);
if (ret == -ENOTCONN)
svc_close_xprt(sxprt);
}
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);
xprt->cwnd = RPC_CWNDSHIFT;
}
static void
xprt_rdma_bc_put(struct rpc_xprt *xprt)
{
dprintk("svcrdma: %s: xprt %p\n", __func__, 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)) {
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(
|