- 根目录:
- net
- sunrpc
- xprtrdma
- svc_rdma_recvfrom.c
/*
* Copyright (c) 2014 Open Grid Computing, Inc. All rights reserved.
* Copyright (c) 2005-2006 Network Appliance, Inc. All rights reserved.
*
* This software is available to you under a choice of one of two
* licenses. You may choose to be licensed under the terms of the GNU
* General Public License (GPL) Version 2, available from the file
* COPYING in the main directory of this source tree, or the BSD-type
* license below:
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided
* with the distribution.
*
* Neither the name of the Network Appliance, Inc. nor the names of
* its contributors may be used to endorse or promote products
* derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* Author: Tom Tucker <tom@opengridcomputing.com>
*/
#include <linux/sunrpc/debug.h>
#include <linux/sunrpc/rpc_rdma.h>
#include <linux/spinlock.h>
#include <asm/unaligned.h>
#include <rdma/ib_verbs.h>
#include <rdma/rdma_cm.h>
#include <linux/sunrpc/svc_rdma.h>
#define RPCDBG_FACILITY RPCDBG_SVCXPRT
/*
* Replace the pages in the rq_argpages array with the pages from the SGE in
* the RDMA_RECV completion. The SGL should contain full pages up until the
* last one.
*/
static void rdma_build_arg_xdr(struct svc_rqst *rqstp,
struct svc_rdma_op_ctxt *ctxt,
u32 byte_count)
{
struct rpcrdma_msg *rmsgp;
struct page *page;
u32 bc;
int sge_no;
/* Swap the page in the SGE with the page in argpages */
page = ctxt->pages[0];
put_page(rqstp->rq_pages[0]);
rqstp->rq_pages[0] = page;
/* Set up the XDR head */
rqstp->rq_arg.head[0].iov_base = page_address(page);
rqstp->rq_arg.head[0].iov_len =
min_t(size_t, byte_count, ctxt->sge[0].length);
rqstp->rq_arg.len = byte_count;
rqstp->rq_arg.buflen = byte_count;
/* Compute bytes past head in the SGL */
bc = byte_count - rqstp->rq_arg.head[0].iov_len;
/* If data remains, store it in the pagelist */
rqstp->rq_arg.page_len = bc;
rqstp->rq_arg.page_base = 0;
/* RDMA_NOMSG: RDMA READ data should land just after RDMA RECV data */
rmsgp = (struct rpcrdma_msg *)rqstp->rq_arg.head[0].iov_base;
if (rmsgp->rm_type == rdma_nomsg)
rqstp->rq_arg.pages = &rqstp->rq_pages[0];
else
rqstp->rq_arg.pages = &rqstp->rq_pages[1];
sge_no = 1;
while (bc && sge_no < ctxt->count) {
page = ctxt->pages[sge_no];
put_page(rqstp->rq_pages[sge_no]);
rqstp->rq_pages[sge_no] = page;
bc -= min_t(u32, bc, ctxt->sge[sge_no].length);
rqstp->rq_arg.buflen += ctxt->sge[sge_no].length;
sge_no++;
}
rqstp->rq_respages = &rqstp->rq_pages[sge_no];
rqstp->rq_next_page = rqstp->rq_respages + 1;
/* If not all pages were used from the SGL, free the remaining ones */
bc = sge_no;
while (sge_no < ctxt->count) {
page = ctxt->pages[sge_no++];
put_page(page);
}
ctxt->count = bc;
/* Set up tail */
rqstp->rq_arg.tail[0].iov_base = NULL;
rqstp->rq_arg.tail[0].iov_len = 0;
}
/* Issue an RDMA_READ using the local lkey to map the data sink */
int rdma_read_chunk_lcl(struct svcxprt_rdma *xprt,
struct svc_rqst *rqstp,
struct svc_rdma_op_ctxt *head,
int *page_no,
u32 *page_offset,
u32 rs_handle,
u32 rs_length,
u64 rs_offset,
bool last)
{
struct ib_rdma_wr read_wr;
int pages_needed = PAGE_ALIGN(*page_offset + rs_length) >> PAGE_SHIFT;
struct svc_rdma_op_ctxt *ctxt = svc_rdma_get_context(xprt);
int ret, read, pno;
u32 pg_off = *page_offset;
u32 pg_no = *page_no;
ctxt->direction = DMA_FROM_DEVICE;
ctxt->read_hdr = head;
pages_needed = min_t(int, pages_needed, xprt->sc_max_sge_rd);
read = min_t(int, (pages_needed << PAGE_SHIFT) - *page_offset,
rs_length);
for (pno = 0; pno < pages_needed; pno++) {
int len = min_t(int, rs_length, PAGE_SIZE - pg_off);
head->arg.pages[pg_no] = rqstp->rq_arg.pages[pg_no];
head->arg.page_len += len;
head->arg.len += len;
if (!pg_off)
head->count++;
rqstp->rq_respages = &rqstp->rq_arg.pages[pg_no+1];
rqstp->rq_next_page = rqstp->rq_respages + 1;
ctxt->sge[pno].addr =
ib_dma_map_page(xprt->sc_cm_id->device,
head->arg.pages[pg_no], pg_off,
PAGE_SIZE - pg_off,
DMA_FROM_DEVICE);
ret = ib_dma_mapping_error(xprt->sc_cm_id->device,
ctxt->sge[pno].addr);
if (ret)
goto err;
atomic_inc(&xprt->sc_dma_used);
/* The lkey here is either a local dma lkey or a dma_mr lkey */
ctxt->sge[pno].lkey = xprt->sc_dma_lkey;
ctxt->sge[pno].length = len;
ctxt->count++;
/* adjust offset and wrap to next page if needed */
pg_off += len;
if (pg_off == PAGE_SIZE) {
pg_off = 0;
pg_no++;
}
rs_length -= len;
}
if (last && rs_length == 0)
set_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags);
else
clear_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags);
memset(&read_wr, 0, sizeof(read_wr));
read_wr.wr.wr_id = (unsigned long)ctxt;
read_wr.wr.opcode = IB_WR_RDMA_READ;
ctxt->wr_op = read_wr.wr.opcode;
read_wr.wr.send_flags = IB_SEND_SIGNALED;
read_wr.rkey = rs_handle;
read_wr.remote_addr = rs_offset;
read_wr.wr.sg_list = ctxt->sge;
read_wr.wr.num_sge = pages_needed;
ret = svc_rdma_send(xprt, &read_wr.wr);
if (ret) {
pr_err("svcrdma: Error %d posting RDMA_READ\n", ret);
set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);
goto err;
}
/* return current location in page array */
*page_no = pg_no;
*page_offset = pg_off;
ret = read;
atomic_inc(&rdma_stat_read);
return ret;
err:
svc_rdma_unmap_dma(ctxt);
svc_rdma_put_context(ctxt, 0);
return ret;
}
/* Issue an RDMA_READ using an FRMR to map the data sink */
int rdma_read_chunk_frmr(struct svcxprt_rdma *xprt,
struct svc_rqst *rqstp,
struct svc_rdma_op_ctxt *head,
int *page_no,
u32 *page_offset,
u32 rs_handle,
u32 rs_length,
u64 rs_offset,
bool last)
{
struct ib_rdma_wr read_wr;
struct ib_send_wr inv_wr;
struct ib_reg_wr reg_wr;
u8 key;
int nents = PAGE_ALIGN(*page_offset + rs_length) >> PAGE_SHIFT;
struct svc_rdma_op_ctxt *ctxt = svc_rdma_get_context(xprt);
struct svc_rdma_fastreg_mr *frmr = svc_rdma_get_frmr(xprt);
int ret, read, pno, dma_nents, n;
u32 pg_off = *page_offset;
u32 pg_no = *page_no;
if (IS_ERR(frmr))
return -ENOMEM;
ctxt->direction = DMA_FROM_DEVICE;
ctxt->frmr = frmr;
nents = min_t(unsigned int, nents, xprt->sc_frmr_pg_list_len);
read = min_t(int, (nents << PAGE_SHIFT) - *page_offset, rs_length);
frmr->direction = DMA_FROM_DEVICE;
frmr->access_flags = (IB_ACCESS_LOCAL_WRITE|IB_ACCESS_REMOTE_WRITE);
frmr->sg_nents = nents;
for (pno = 0; pno < nents; pno++) {
int len = min_t(int, rs_length, PAGE_SIZE - pg_off);
head->arg.pages[pg_no] = rqstp->rq_arg.pages[pg_no];
head->arg.page_len += len;
head->arg.len += len;
if (!pg_off)
head->count++;
sg_set_page(&frmr->sg[pno], rqstp->rq_arg.pages[pg_no],
len, pg_off);
rqstp->rq_respages = &rqstp->rq_arg.pages[pg_no+1];
rqstp->rq_next_page = rqstp->rq_respages + 1;
/* adjust offset and wrap to next page if needed */
pg_off += len;
if (pg_off == PAGE_SIZE) {
pg_off = 0;
pg_no++;
}
rs_length -= len;
}
if (last && rs_length == 0)
set_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags);
else
clear_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags);
dma_nents = ib_dma_map_sg(xprt->sc_cm_id->device,
frmr->sg, frmr->sg_nents,
frmr->direction);
if (!dma_nents) {
pr_err("svcrdma: failed to dma map sg %p\n",
frmr->sg);
return -ENOMEM;
}
atomic_inc(&xprt->sc_dma_used);
n = ib_map_mr_sg(frmr->mr, frmr->sg, frmr->sg_nents, PAGE_SIZE);
if (unlikely(n != frmr->sg_nents)) {
pr_err("svcrdma: failed to map mr %p (%d/%d elements)\n",
frmr->mr, n, frmr->sg_nents);
return n < 0 ? n : -EINVAL;
}
/* Bump the key */
key = (u8)(frmr->mr->lkey & 0x000000FF);
ib_update_fast_reg_key(frmr->mr, ++key);
ctxt->sge[0].addr = frmr->mr->iova;
ctxt->sge[0].lkey = frmr->mr->lkey;
ctxt->sge[0].length = frmr->mr->length;
ctxt->count = 1;
ctxt->read_hdr = head;
/* Prepare REG WR */
reg_wr.wr.opcode = IB_WR_REG_MR;
reg_wr.wr.wr_id = 0;
reg_wr.wr.send_flags = IB_SEND_SIGNALED;
reg_wr.wr.num_sge = 0;
reg_wr.mr = frmr->mr;
reg_wr.key = frmr->mr->lkey;
reg_wr.access = frmr->access_flags;
reg_wr.wr.next = &read_wr.wr;
/* Prepare RDMA_READ */
memset(&read_wr, 0, sizeof(read_wr));
read_wr.wr.send_flags = IB_SEND_SIGNALED;
read_wr.rkey = rs_handle;
read_wr.remote_addr = rs_offset;
read_wr.wr.sg_list = ctxt->sge;
read_wr.wr.num_sge = 1;
if (xprt->sc_dev_caps & SVCRDMA_DEVCAP_READ_W_INV) {
read_wr.wr.opcode = IB_WR_RDMA_READ_WITH_INV;
read_wr.wr.wr_id = (unsigned long)ctxt;
read_wr.wr.ex.invalidate_rkey = ctxt->frmr->mr->lkey;
} else {
read_wr.wr.opcode = IB_WR_RDMA_READ;
read_wr.wr.next = &inv_wr;
/* Prepare invalidate */
memset(&inv_wr, 0, sizeof(inv_wr));
inv_wr.wr_id = (unsigned long)ctxt;
inv_wr.opcode = IB_WR_LOCAL_INV;
inv_wr.send_flags = IB_SEND_SIGNALED | IB_SEND_FENCE;
inv_wr.ex.invalidate_rkey = frmr->mr->lkey;
}
ctxt->wr_op = read_wr.wr.opcode;
/* Post the chain */
ret = svc_rdma_send(xprt, ®_wr.wr);
if (ret) {
pr_err("svcrdma: Error %d posting RDMA_READ\n", ret);
set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);
goto err;
}
/* return current location in page array */
*page_no = pg_no;
*page_offset = pg_off;
ret = read;
atomic_inc(&rdma_stat_read);
return ret;
err:
ib_dma_unmap_sg(xprt->sc_cm_id->device,
frmr->sg, frmr->sg_nents, frmr->direction);
svc_rdma_put_context(ctxt, 0);
svc_rdma_put_frmr(xprt, frmr);
return ret;
}
static unsigned int
rdma_rcl_chunk_count(struct rpcrdma_read_chunk *ch)
{
unsigned int count;
for (count = 0; ch->rc_discrim != xdr_zero; ch++)
count++;
return count;
}
/* If there was additional inline content, append it to the end of arg.pages.
* Tail copy has to be done after the reader function has determined how many
* pages are needed for RDMA READ.
*/
static int
rdma_copy_tail(struct svc_rqst *rqstp, struct svc_rdma_op_ctxt *head,
u32 position, u32 byte_count, u32 page_offset, int page_no)
{
char *srcp, *destp;
int ret;
ret = 0;
srcp = head->arg.head[0].iov_base + position;
byte_count = head->arg.head[0].iov_len - position;
if (byte_count > PAGE_SIZE) {
dprintk("svcrdma: large tail unsupported\n");
return 0;
}
/* Fit as much of the tail on the current page as possible */
if (page_offset != PAGE_SIZE) {
destp = page_address(rqstp->rq_arg.pages[page_no]);
destp += page_offset;
while (byte_count--) {
*destp++ = *srcp++;
page_offset++;
if (page_offset == PAGE_SIZE && byte_count)
goto more;
}
goto done;
}
more:
/* Fit the rest on the next page */
page_no++;
destp = page_address(rqstp->rq_arg.pages[page_no]);
while (byte_count--)
*destp++ = *srcp++;
rqstp->rq_respages = &rqstp->rq_arg.pages[page_no+1];
rqstp->rq_next_page = rqstp->rq_respages + 1;
done:
byte_count = head->arg.head[0].iov_len - position;
head->arg.page_len += byte_count;
head->arg.len += byte_count;
head->arg.buflen += byte_count;
return 1;
}
static int rdma_read_chunks(struct svcxprt_rdma *xprt,
struct rpcrdma_msg *rmsgp,
struct svc_rqst *rqstp,
struct svc_rdma_op_ctxt *head)
{
int page_no, ret;
struct rpcrdma_read_chunk *ch;
u32 handle, page_offset, byte_count;
u32 position;
u64 rs_offset;
bool last;
/* If no read list is present, return 0 */
ch = svc_rdma_get_read_chunk(rmsgp);
if (!ch)
return 0;
if (rdma_rcl_chunk_count(ch) > RPCSVC_MAXPAGES)
return -EINVAL;
/* The request is completed when the RDMA_READs complete. The
* head context keeps all the pages that comprise the
* request.
*/
head->arg.head[0] = rqstp->rq_arg.head[0];
head->arg.tail[0] = rqstp->rq_arg.tail[0];
head->hdr_count = head->count;
head->arg.page_base = 0;
head->arg.page_len = 0;
head->arg.len = rqstp->rq_arg.len;
head->arg.buflen = rqstp->rq_arg.buflen;
ch = (struct rpcrdma_read_chunk *)&rmsgp->rm_body.rm_chunks[0];
position = be32_to_cpu(ch->rc_position);
/* RDMA_NOMSG: RDMA READ data should land just after RDMA RECV data */
if (position == 0) {
head->arg.pages = &head->pages[0];
page_offset = head->byte_len;
} else {
head->arg.pages = &head->pages[head->count];
page_offset = 0;
}
ret = 0;
page_no = 0;
for (; ch->rc_discrim != xdr_zero; ch++) {
if (be32_to_cpu(ch->rc_position) != position)
goto err;
handle = be32_to_cpu(ch->rc_target.rs_handle),
byte_count = be32_to_cpu(ch->rc_target.rs_length);
xdr_decode_hyper((__be32 *)&ch->rc_target.rs_offset,
&rs_offset);
while (byte_count > 0) {
last = (ch + 1)->rc_discrim == xdr_zero;
ret = xprt->sc_reader(xprt, rqstp, head,
&page_no, &page_offset,
handle, byte_count,
rs_offset, last);
if (ret < 0)
goto err;
byte_count -= ret;
rs_offset += ret;
head->arg.buflen += ret;
}
}
/* Read list may need XDR round-up (see RFC 5666, s. 3.7) */
if (page_offset & 3) {
u32 pad = 4 - (page_offset & 3);
head->arg.page_len += pad;
head->arg.len += pad;
head->arg.buflen += pad;
page_offset += pad;
}
ret = 1;
if (position && position < head->arg.head[0].iov_len)
ret = rdma_copy_tail(rqstp, head, position,
byte_count, page_offset, page_no);
head->arg.head[0].iov_len = position;
head->position = position;
err:
/* Detach arg pages. svc_recv will replenish them */
for (page_no = 0;
&rqstp->rq_pages[page_no] < rqstp->rq_respages; page_no++)
rqstp->rq_pages[page_no] = NULL;
return ret;
}
static int rdma_read_complete(struct svc_rqst *rqstp,
struct svc_rdma_op_ctxt *head)
{
int page_no;
int ret;
/* Copy RPC pages */
for (page_no = 0; page_no < head->count; page_no++) {
put_page(rqstp->rq_pages[page_no]);
rqstp->rq_pages[page_no] = head->pages[page_no];
}
/* Adjustments made for RDMA_NOMSG type requests */
if (head->position == 0) {
if (head->arg.len <= head->sge[0].length) {
head->arg.head[0].iov_len = head->arg.len -
head->byte_len;
head->arg.page_len = 0;
} else {
head->arg.head[0].iov_len = head->sge[0].length -
head->byte_len;
head->arg.page_len = head->arg.len -
head->sge[0].length;
}
}
/* Point rq_arg.pages past header */
rqstp->rq_arg.pages = &rqstp->rq_pages[head->hdr_count];
rqstp->rq_arg.page_len = head->arg.page_len;
rqstp->rq_arg.page_base = head->arg.page_base;
/* rq_respages starts after the last arg page */
rqstp->rq_respages = &rqstp->rq_pages[page_no];
rqstp->rq_next_page = rqstp->rq_respages + 1;
/* Rebuild rq_arg head and tail. */
rqstp->rq_arg.head[0] = head->arg.head[0];
rqstp->rq_arg.tail[0] = head->arg.tail[0];
rqstp->rq_arg.len = head->arg.len;
rqstp->rq_arg.buflen = head->arg.buflen;
/* Free the context */
svc_rdma_put_context(head, 0);
/* XXX: What should this be? */
rqstp->rq_prot = IPPROTO_MAX;
svc_xprt_copy_addrs(rqstp, rqstp->rq_xprt);
ret = rqstp->rq_arg.head[0].iov_len
+ rqstp->rq_arg.page_len
+ rqstp->rq_arg.tail[0].iov_len;
dprintk("svcrdma: deferred read ret=%d, rq_arg.len=%u, "
"rq_arg.head[0].iov_base=%p, rq_arg.head[0].iov_len=%zu\n",
ret, rqstp->rq_arg.len, rqstp->rq_arg.head[0].iov_base,
rqstp->rq_arg.head[0].iov_len);
return ret;
}
/*
* Set up the rqstp thread context to point to the RQ buffer. If
* necessary, pull additional data from the client with an RDMA_READ
* request.
*/
int svc_rdma_recvfrom(struct svc_rqst *rqstp)
{
struct svc_xprt *xprt = rqstp->rq_xprt;
struct svcxprt_rdma *rdma_xprt =
container_of(xprt, struct svcxprt_rdma, sc_xprt);
struct svc_rdma_op_ctxt *ctxt = NULL;
struct rpcrdma_msg *rmsgp;
int ret = 0;
int len;
dprintk("svcrdma: rqstp=%p\n", rqstp);
spin_lock_bh(&rdma_xprt->sc_rq_dto_lock);
if (!list_empty(&rdma_xprt->sc_read_complete_q)) {
ctxt = list_entry(rdma_xprt->sc_read_complete_q.next,
struct svc_rdma_op_ctxt,
dto_q);
list_del_init(&ctxt->dto_q);
spin_unlock_bh(&rdma_xprt->sc_rq_dto_lock);
return rdma_read_complete(rqstp, ctxt);
} else if (!list_empty(&rdma_xprt->sc_rq_dto_q)) {
ctxt = list_entry(rdma_xprt->sc_rq_dto_q.next,
struct svc_rdma_op_ctxt,
dto_q);
list_del_init(&ctxt->dto_q);
} else {
atomic_inc(&rdma_stat_rq_starve);
clear_bit(XPT_DATA, &xprt->xpt_flags);
ctxt = NULL;
}
spin_unlock_bh(&rdma_xprt->sc_rq_dto_lock);
if (!ctxt) {
/* This is the EAGAIN path. The svc_recv routine will
* return -EAGAIN, the nfsd thread will go to call into
* svc_recv again and we shouldn't be on the active
* transport list
*/
if (test_bit(XPT_CLOSE, &xprt->xpt_flags))
goto close_out;
goto out;
}
dprintk("svcrdma: processing ctxt=%p on xprt=%p, rqstp=%p, status=%d\n",
ctxt, rdma_xprt, rqstp, ctxt->wc_status);
atomic_inc(&rdma_stat_recv);
/* Build up the XDR from the receive buffers. */
rdma_build_arg_xdr(rqstp, ctxt, ctxt->byte_len);
/* Decode the RDMA header. */
len = svc_rdma_xdr_decode_req(&rmsgp, rqstp);
rqstp->rq_xprt_hlen = len;
/* If the request is invalid, reply with an error */
if (len < 0) {
if (len == -ENOSYS)
svc_rdma_send_error(rdma_xprt, rmsgp, ERR_VERS);
goto close_out;
}
/* Read read-list data. */
ret = rdma_read_chunks(rdma_xprt, rmsgp, rqstp, ctxt);
if (ret > 0) {
/* read-list posted, defer until data received from client. */
goto defer;
} else if (ret < 0) {
/* Post of read-list failed, free context. */
svc_rdma_put_context(ctxt, 1);
return 0;
}
ret = rqstp->rq_arg.head[0].iov_len
+ rqstp->rq_arg.page_len
+ rqstp->rq_arg.tail[0].iov_len;
svc_rdma_put_context(ctxt, 0);
out:
dprintk("svcrdma: ret=%d, rq_arg.len=%u, "
"rq_arg.head[0].iov_base=%p, rq_arg.head[0].iov_len=%zd\n",
ret, rqstp->rq_arg.len,
rqstp->rq_arg.head[0].iov_base,
rqstp->rq_arg.head[0].iov_len);
rqstp->rq_prot = IPPROTO_MAX;
svc_xprt_copy_addrs(rqstp, xprt);
return ret;
close_out:
if (ctxt)
svc_rdma_put_context(ctxt, 1);
dprintk("svcrdma: transport %p is closing\n", xprt);
/*
* Set the close bit and enqueue it. svc_recv will see the
* close bit and call svc_xprt_delete
*/
set_bit(XPT_CLOSE, &xprt->xpt_flags);
defer:
return 0;
}