swh:1:snp:49cd9498d6cccc5e78252c27dcb645bcf7bf0c91
Tip revision: 0238df646e6224016a45505d2c111a24669ebe21 authored by Greg Kroah-Hartman on 07 October 2018, 15:26:02 UTC
Linux 4.19-rc7
Linux 4.19-rc7
Tip revision: 0238df6
svc_rdma_recvfrom.c
// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
/*
* Copyright (c) 2016-2018 Oracle. All rights reserved.
* 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>
*/
/* Operation
*
* The main entry point is svc_rdma_recvfrom. This is called from
* svc_recv when the transport indicates there is incoming data to
* be read. "Data Ready" is signaled when an RDMA Receive completes,
* or when a set of RDMA Reads complete.
*
* An svc_rqst is passed in. This structure contains an array of
* free pages (rq_pages) that will contain the incoming RPC message.
*
* Short messages are moved directly into svc_rqst::rq_arg, and
* the RPC Call is ready to be processed by the Upper Layer.
* svc_rdma_recvfrom returns the length of the RPC Call message,
* completing the reception of the RPC Call.
*
* However, when an incoming message has Read chunks,
* svc_rdma_recvfrom must post RDMA Reads to pull the RPC Call's
* data payload from the client. svc_rdma_recvfrom sets up the
* RDMA Reads using pages in svc_rqst::rq_pages, which are
* transferred to an svc_rdma_recv_ctxt for the duration of the
* I/O. svc_rdma_recvfrom then returns zero, since the RPC message
* is still not yet ready.
*
* When the Read chunk payloads have become available on the
* server, "Data Ready" is raised again, and svc_recv calls
* svc_rdma_recvfrom again. This second call may use a different
* svc_rqst than the first one, thus any information that needs
* to be preserved across these two calls is kept in an
* svc_rdma_recv_ctxt.
*
* The second call to svc_rdma_recvfrom performs final assembly
* of the RPC Call message, using the RDMA Read sink pages kept in
* the svc_rdma_recv_ctxt. The xdr_buf is copied from the
* svc_rdma_recv_ctxt to the second svc_rqst. The second call returns
* the length of the completed RPC Call message.
*
* Page Management
*
* Pages under I/O must be transferred from the first svc_rqst to an
* svc_rdma_recv_ctxt before the first svc_rdma_recvfrom call returns.
*
* The first svc_rqst supplies pages for RDMA Reads. These are moved
* from rqstp::rq_pages into ctxt::pages. The consumed elements of
* the rq_pages array are set to NULL and refilled with the first
* svc_rdma_recvfrom call returns.
*
* During the second svc_rdma_recvfrom call, RDMA Read sink pages
* are transferred from the svc_rdma_recv_ctxt to the second svc_rqst
* (see rdma_read_complete() below).
*/
#include <linux/spinlock.h>
#include <asm/unaligned.h>
#include <rdma/ib_verbs.h>
#include <rdma/rdma_cm.h>
#include <linux/sunrpc/xdr.h>
#include <linux/sunrpc/debug.h>
#include <linux/sunrpc/rpc_rdma.h>
#include <linux/sunrpc/svc_rdma.h>
#include "xprt_rdma.h"
#include <trace/events/rpcrdma.h>
#define RPCDBG_FACILITY RPCDBG_SVCXPRT
static void svc_rdma_wc_receive(struct ib_cq *cq, struct ib_wc *wc);
static inline struct svc_rdma_recv_ctxt *
svc_rdma_next_recv_ctxt(struct list_head *list)
{
return list_first_entry_or_null(list, struct svc_rdma_recv_ctxt,
rc_list);
}
static struct svc_rdma_recv_ctxt *
svc_rdma_recv_ctxt_alloc(struct svcxprt_rdma *rdma)
{
struct svc_rdma_recv_ctxt *ctxt;
dma_addr_t addr;
void *buffer;
ctxt = kmalloc(sizeof(*ctxt), GFP_KERNEL);
if (!ctxt)
goto fail0;
buffer = kmalloc(rdma->sc_max_req_size, GFP_KERNEL);
if (!buffer)
goto fail1;
addr = ib_dma_map_single(rdma->sc_pd->device, buffer,
rdma->sc_max_req_size, DMA_FROM_DEVICE);
if (ib_dma_mapping_error(rdma->sc_pd->device, addr))
goto fail2;
ctxt->rc_recv_wr.next = NULL;
ctxt->rc_recv_wr.wr_cqe = &ctxt->rc_cqe;
ctxt->rc_recv_wr.sg_list = &ctxt->rc_recv_sge;
ctxt->rc_recv_wr.num_sge = 1;
ctxt->rc_cqe.done = svc_rdma_wc_receive;
ctxt->rc_recv_sge.addr = addr;
ctxt->rc_recv_sge.length = rdma->sc_max_req_size;
ctxt->rc_recv_sge.lkey = rdma->sc_pd->local_dma_lkey;
ctxt->rc_recv_buf = buffer;
ctxt->rc_temp = false;
return ctxt;
fail2:
kfree(buffer);
fail1:
kfree(ctxt);
fail0:
return NULL;
}
static void svc_rdma_recv_ctxt_destroy(struct svcxprt_rdma *rdma,
struct svc_rdma_recv_ctxt *ctxt)
{
ib_dma_unmap_single(rdma->sc_pd->device, ctxt->rc_recv_sge.addr,
ctxt->rc_recv_sge.length, DMA_FROM_DEVICE);
kfree(ctxt->rc_recv_buf);
kfree(ctxt);
}
/**
* svc_rdma_recv_ctxts_destroy - Release all recv_ctxt's for an xprt
* @rdma: svcxprt_rdma being torn down
*
*/
void svc_rdma_recv_ctxts_destroy(struct svcxprt_rdma *rdma)
{
struct svc_rdma_recv_ctxt *ctxt;
while ((ctxt = svc_rdma_next_recv_ctxt(&rdma->sc_recv_ctxts))) {
list_del(&ctxt->rc_list);
svc_rdma_recv_ctxt_destroy(rdma, ctxt);
}
}
static struct svc_rdma_recv_ctxt *
svc_rdma_recv_ctxt_get(struct svcxprt_rdma *rdma)
{
struct svc_rdma_recv_ctxt *ctxt;
spin_lock(&rdma->sc_recv_lock);
ctxt = svc_rdma_next_recv_ctxt(&rdma->sc_recv_ctxts);
if (!ctxt)
goto out_empty;
list_del(&ctxt->rc_list);
spin_unlock(&rdma->sc_recv_lock);
out:
ctxt->rc_page_count = 0;
return ctxt;
out_empty:
spin_unlock(&rdma->sc_recv_lock);
ctxt = svc_rdma_recv_ctxt_alloc(rdma);
if (!ctxt)
return NULL;
goto out;
}
/**
* svc_rdma_recv_ctxt_put - Return recv_ctxt to free list
* @rdma: controlling svcxprt_rdma
* @ctxt: object to return to the free list
*
*/
void svc_rdma_recv_ctxt_put(struct svcxprt_rdma *rdma,
struct svc_rdma_recv_ctxt *ctxt)
{
unsigned int i;
for (i = 0; i < ctxt->rc_page_count; i++)
put_page(ctxt->rc_pages[i]);
if (!ctxt->rc_temp) {
spin_lock(&rdma->sc_recv_lock);
list_add(&ctxt->rc_list, &rdma->sc_recv_ctxts);
spin_unlock(&rdma->sc_recv_lock);
} else
svc_rdma_recv_ctxt_destroy(rdma, ctxt);
}
static int __svc_rdma_post_recv(struct svcxprt_rdma *rdma,
struct svc_rdma_recv_ctxt *ctxt)
{
int ret;
svc_xprt_get(&rdma->sc_xprt);
ret = ib_post_recv(rdma->sc_qp, &ctxt->rc_recv_wr, NULL);
trace_svcrdma_post_recv(&ctxt->rc_recv_wr, ret);
if (ret)
goto err_post;
return 0;
err_post:
svc_rdma_recv_ctxt_put(rdma, ctxt);
svc_xprt_put(&rdma->sc_xprt);
return ret;
}
static int svc_rdma_post_recv(struct svcxprt_rdma *rdma)
{
struct svc_rdma_recv_ctxt *ctxt;
ctxt = svc_rdma_recv_ctxt_get(rdma);
if (!ctxt)
return -ENOMEM;
return __svc_rdma_post_recv(rdma, ctxt);
}
/**
* svc_rdma_post_recvs - Post initial set of Recv WRs
* @rdma: fresh svcxprt_rdma
*
* Returns true if successful, otherwise false.
*/
bool svc_rdma_post_recvs(struct svcxprt_rdma *rdma)
{
struct svc_rdma_recv_ctxt *ctxt;
unsigned int i;
int ret;
for (i = 0; i < rdma->sc_max_requests; i++) {
ctxt = svc_rdma_recv_ctxt_get(rdma);
if (!ctxt)
return false;
ctxt->rc_temp = true;
ret = __svc_rdma_post_recv(rdma, ctxt);
if (ret) {
pr_err("svcrdma: failure posting recv buffers: %d\n",
ret);
return false;
}
}
return true;
}
/**
* svc_rdma_wc_receive - Invoked by RDMA provider for each polled Receive WC
* @cq: Completion Queue context
* @wc: Work Completion object
*
* NB: The svc_xprt/svcxprt_rdma is pinned whenever it's possible that
* the Receive completion handler could be running.
*/
static void svc_rdma_wc_receive(struct ib_cq *cq, struct ib_wc *wc)
{
struct svcxprt_rdma *rdma = cq->cq_context;
struct ib_cqe *cqe = wc->wr_cqe;
struct svc_rdma_recv_ctxt *ctxt;
trace_svcrdma_wc_receive(wc);
/* WARNING: Only wc->wr_cqe and wc->status are reliable */
ctxt = container_of(cqe, struct svc_rdma_recv_ctxt, rc_cqe);
if (wc->status != IB_WC_SUCCESS)
goto flushed;
if (svc_rdma_post_recv(rdma))
goto post_err;
/* All wc fields are now known to be valid */
ctxt->rc_byte_len = wc->byte_len;
ib_dma_sync_single_for_cpu(rdma->sc_pd->device,
ctxt->rc_recv_sge.addr,
wc->byte_len, DMA_FROM_DEVICE);
spin_lock(&rdma->sc_rq_dto_lock);
list_add_tail(&ctxt->rc_list, &rdma->sc_rq_dto_q);
spin_unlock(&rdma->sc_rq_dto_lock);
set_bit(XPT_DATA, &rdma->sc_xprt.xpt_flags);
if (!test_bit(RDMAXPRT_CONN_PENDING, &rdma->sc_flags))
svc_xprt_enqueue(&rdma->sc_xprt);
goto out;
flushed:
if (wc->status != IB_WC_WR_FLUSH_ERR)
pr_err("svcrdma: Recv: %s (%u/0x%x)\n",
ib_wc_status_msg(wc->status),
wc->status, wc->vendor_err);
post_err:
svc_rdma_recv_ctxt_put(rdma, ctxt);
set_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags);
svc_xprt_enqueue(&rdma->sc_xprt);
out:
svc_xprt_put(&rdma->sc_xprt);
}
/**
* svc_rdma_flush_recv_queues - Drain pending Receive work
* @rdma: svcxprt_rdma being shut down
*
*/
void svc_rdma_flush_recv_queues(struct svcxprt_rdma *rdma)
{
struct svc_rdma_recv_ctxt *ctxt;
while ((ctxt = svc_rdma_next_recv_ctxt(&rdma->sc_read_complete_q))) {
list_del(&ctxt->rc_list);
svc_rdma_recv_ctxt_put(rdma, ctxt);
}
while ((ctxt = svc_rdma_next_recv_ctxt(&rdma->sc_rq_dto_q))) {
list_del(&ctxt->rc_list);
svc_rdma_recv_ctxt_put(rdma, ctxt);
}
}
static void svc_rdma_build_arg_xdr(struct svc_rqst *rqstp,
struct svc_rdma_recv_ctxt *ctxt)
{
struct xdr_buf *arg = &rqstp->rq_arg;
arg->head[0].iov_base = ctxt->rc_recv_buf;
arg->head[0].iov_len = ctxt->rc_byte_len;
arg->tail[0].iov_base = NULL;
arg->tail[0].iov_len = 0;
arg->page_len = 0;
arg->page_base = 0;
arg->buflen = ctxt->rc_byte_len;
arg->len = ctxt->rc_byte_len;
}
/* This accommodates the largest possible Write chunk,
* in one segment.
*/
#define MAX_BYTES_WRITE_SEG ((u32)(RPCSVC_MAXPAGES << PAGE_SHIFT))
/* This accommodates the largest possible Position-Zero
* Read chunk or Reply chunk, in one segment.
*/
#define MAX_BYTES_SPECIAL_SEG ((u32)((RPCSVC_MAXPAGES + 2) << PAGE_SHIFT))
/* Sanity check the Read list.
*
* Implementation limits:
* - This implementation supports only one Read chunk.
*
* Sanity checks:
* - Read list does not overflow buffer.
* - Segment size limited by largest NFS data payload.
*
* The segment count is limited to how many segments can
* fit in the transport header without overflowing the
* buffer. That's about 40 Read segments for a 1KB inline
* threshold.
*
* Returns pointer to the following Write list.
*/
static __be32 *xdr_check_read_list(__be32 *p, const __be32 *end)
{
u32 position;
bool first;
first = true;
while (*p++ != xdr_zero) {
if (first) {
position = be32_to_cpup(p++);
first = false;
} else if (be32_to_cpup(p++) != position) {
return NULL;
}
p++; /* handle */
if (be32_to_cpup(p++) > MAX_BYTES_SPECIAL_SEG)
return NULL;
p += 2; /* offset */
if (p > end)
return NULL;
}
return p;
}
/* The segment count is limited to how many segments can
* fit in the transport header without overflowing the
* buffer. That's about 60 Write segments for a 1KB inline
* threshold.
*/
static __be32 *xdr_check_write_chunk(__be32 *p, const __be32 *end,
u32 maxlen)
{
u32 i, segcount;
segcount = be32_to_cpup(p++);
for (i = 0; i < segcount; i++) {
p++; /* handle */
if (be32_to_cpup(p++) > maxlen)
return NULL;
p += 2; /* offset */
if (p > end)
return NULL;
}
return p;
}
/* Sanity check the Write list.
*
* Implementation limits:
* - This implementation supports only one Write chunk.
*
* Sanity checks:
* - Write list does not overflow buffer.
* - Segment size limited by largest NFS data payload.
*
* Returns pointer to the following Reply chunk.
*/
static __be32 *xdr_check_write_list(__be32 *p, const __be32 *end)
{
u32 chcount;
chcount = 0;
while (*p++ != xdr_zero) {
p = xdr_check_write_chunk(p, end, MAX_BYTES_WRITE_SEG);
if (!p)
return NULL;
if (chcount++ > 1)
return NULL;
}
return p;
}
/* Sanity check the Reply chunk.
*
* Sanity checks:
* - Reply chunk does not overflow buffer.
* - Segment size limited by largest NFS data payload.
*
* Returns pointer to the following RPC header.
*/
static __be32 *xdr_check_reply_chunk(__be32 *p, const __be32 *end)
{
if (*p++ != xdr_zero) {
p = xdr_check_write_chunk(p, end, MAX_BYTES_SPECIAL_SEG);
if (!p)
return NULL;
}
return p;
}
/* On entry, xdr->head[0].iov_base points to first byte in the
* RPC-over-RDMA header.
*
* On successful exit, head[0] points to first byte past the
* RPC-over-RDMA header. For RDMA_MSG, this is the RPC message.
* The length of the RPC-over-RDMA header is returned.
*
* Assumptions:
* - The transport header is entirely contained in the head iovec.
*/
static int svc_rdma_xdr_decode_req(struct xdr_buf *rq_arg)
{
__be32 *p, *end, *rdma_argp;
unsigned int hdr_len;
/* Verify that there's enough bytes for header + something */
if (rq_arg->len <= RPCRDMA_HDRLEN_ERR)
goto out_short;
rdma_argp = rq_arg->head[0].iov_base;
if (*(rdma_argp + 1) != rpcrdma_version)
goto out_version;
switch (*(rdma_argp + 3)) {
case rdma_msg:
break;
case rdma_nomsg:
break;
case rdma_done:
goto out_drop;
case rdma_error:
goto out_drop;
default:
goto out_proc;
}
end = (__be32 *)((unsigned long)rdma_argp + rq_arg->len);
p = xdr_check_read_list(rdma_argp + 4, end);
if (!p)
goto out_inval;
p = xdr_check_write_list(p, end);
if (!p)
goto out_inval;
p = xdr_check_reply_chunk(p, end);
if (!p)
goto out_inval;
if (p > end)
goto out_inval;
rq_arg->head[0].iov_base = p;
hdr_len = (unsigned long)p - (unsigned long)rdma_argp;
rq_arg->head[0].iov_len -= hdr_len;
rq_arg->len -= hdr_len;
trace_svcrdma_decode_rqst(rdma_argp, hdr_len);
return hdr_len;
out_short:
trace_svcrdma_decode_short(rq_arg->len);
return -EINVAL;
out_version:
trace_svcrdma_decode_badvers(rdma_argp);
return -EPROTONOSUPPORT;
out_drop:
trace_svcrdma_decode_drop(rdma_argp);
return 0;
out_proc:
trace_svcrdma_decode_badproc(rdma_argp);
return -EINVAL;
out_inval:
trace_svcrdma_decode_parse(rdma_argp);
return -EINVAL;
}
static void rdma_read_complete(struct svc_rqst *rqstp,
struct svc_rdma_recv_ctxt *head)
{
int page_no;
/* Move Read chunk pages to rqstp so that they will be released
* when svc_process is done with them.
*/
for (page_no = 0; page_no < head->rc_page_count; page_no++) {
put_page(rqstp->rq_pages[page_no]);
rqstp->rq_pages[page_no] = head->rc_pages[page_no];
}
head->rc_page_count = 0;
/* Point rq_arg.pages past header */
rqstp->rq_arg.pages = &rqstp->rq_pages[head->rc_hdr_count];
rqstp->rq_arg.page_len = head->rc_arg.page_len;
/* 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->rc_arg.head[0];
rqstp->rq_arg.tail[0] = head->rc_arg.tail[0];
rqstp->rq_arg.len = head->rc_arg.len;
rqstp->rq_arg.buflen = head->rc_arg.buflen;
}
static void svc_rdma_send_error(struct svcxprt_rdma *xprt,
__be32 *rdma_argp, int status)
{
struct svc_rdma_send_ctxt *ctxt;
unsigned int length;
__be32 *p;
int ret;
ctxt = svc_rdma_send_ctxt_get(xprt);
if (!ctxt)
return;
p = ctxt->sc_xprt_buf;
*p++ = *rdma_argp;
*p++ = *(rdma_argp + 1);
*p++ = xprt->sc_fc_credits;
*p++ = rdma_error;
switch (status) {
case -EPROTONOSUPPORT:
*p++ = err_vers;
*p++ = rpcrdma_version;
*p++ = rpcrdma_version;
trace_svcrdma_err_vers(*rdma_argp);
break;
default:
*p++ = err_chunk;
trace_svcrdma_err_chunk(*rdma_argp);
}
length = (unsigned long)p - (unsigned long)ctxt->sc_xprt_buf;
svc_rdma_sync_reply_hdr(xprt, ctxt, length);
ctxt->sc_send_wr.opcode = IB_WR_SEND;
ret = svc_rdma_send(xprt, &ctxt->sc_send_wr);
if (ret)
svc_rdma_send_ctxt_put(xprt, ctxt);
}
/* By convention, backchannel calls arrive via rdma_msg type
* messages, and never populate the chunk lists. This makes
* the RPC/RDMA header small and fixed in size, so it is
* straightforward to check the RPC header's direction field.
*/
static bool svc_rdma_is_backchannel_reply(struct svc_xprt *xprt,
__be32 *rdma_resp)
{
__be32 *p;
if (!xprt->xpt_bc_xprt)
return false;
p = rdma_resp + 3;
if (*p++ != rdma_msg)
return false;
if (*p++ != xdr_zero)
return false;
if (*p++ != xdr_zero)
return false;
if (*p++ != xdr_zero)
return false;
/* XID sanity */
if (*p++ != *rdma_resp)
return false;
/* call direction */
if (*p == cpu_to_be32(RPC_CALL))
return false;
return true;
}
/**
* svc_rdma_recvfrom - Receive an RPC call
* @rqstp: request structure into which to receive an RPC Call
*
* Returns:
* The positive number of bytes in the RPC Call message,
* %0 if there were no Calls ready to return,
* %-EINVAL if the Read chunk data is too large,
* %-ENOMEM if rdma_rw context pool was exhausted,
* %-ENOTCONN if posting failed (connection is lost),
* %-EIO if rdma_rw initialization failed (DMA mapping, etc).
*
* Called in a loop when XPT_DATA is set. XPT_DATA is cleared only
* when there are no remaining ctxt's to process.
*
* The next ctxt is removed from the "receive" lists.
*
* - If the ctxt completes a Read, then finish assembling the Call
* message and return the number of bytes in the message.
*
* - If the ctxt completes a Receive, then construct the Call
* message from the contents of the Receive buffer.
*
* - If there are no Read chunks in this message, then finish
* assembling the Call message and return the number of bytes
* in the message.
*
* - If there are Read chunks in this message, post Read WRs to
* pull that payload and return 0.
*/
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_recv_ctxt *ctxt;
__be32 *p;
int ret;
spin_lock(&rdma_xprt->sc_rq_dto_lock);
ctxt = svc_rdma_next_recv_ctxt(&rdma_xprt->sc_read_complete_q);
if (ctxt) {
list_del(&ctxt->rc_list);
spin_unlock(&rdma_xprt->sc_rq_dto_lock);
rdma_read_complete(rqstp, ctxt);
goto complete;
}
ctxt = svc_rdma_next_recv_ctxt(&rdma_xprt->sc_rq_dto_q);
if (!ctxt) {
/* No new incoming requests, terminate the loop */
clear_bit(XPT_DATA, &xprt->xpt_flags);
spin_unlock(&rdma_xprt->sc_rq_dto_lock);
return 0;
}
list_del(&ctxt->rc_list);
spin_unlock(&rdma_xprt->sc_rq_dto_lock);
atomic_inc(&rdma_stat_recv);
svc_rdma_build_arg_xdr(rqstp, ctxt);
/* Prevent svc_xprt_release from releasing pages in rq_pages
* if we return 0 or an error.
*/
rqstp->rq_respages = rqstp->rq_pages;
rqstp->rq_next_page = rqstp->rq_respages;
p = (__be32 *)rqstp->rq_arg.head[0].iov_base;
ret = svc_rdma_xdr_decode_req(&rqstp->rq_arg);
if (ret < 0)
goto out_err;
if (ret == 0)
goto out_drop;
rqstp->rq_xprt_hlen = ret;
if (svc_rdma_is_backchannel_reply(xprt, p)) {
ret = svc_rdma_handle_bc_reply(xprt->xpt_bc_xprt, p,
&rqstp->rq_arg);
svc_rdma_recv_ctxt_put(rdma_xprt, ctxt);
return ret;
}
p += rpcrdma_fixed_maxsz;
if (*p != xdr_zero)
goto out_readchunk;
complete:
rqstp->rq_xprt_ctxt = ctxt;
rqstp->rq_prot = IPPROTO_MAX;
svc_xprt_copy_addrs(rqstp, xprt);
return rqstp->rq_arg.len;
out_readchunk:
ret = svc_rdma_recv_read_chunk(rdma_xprt, rqstp, ctxt, p);
if (ret < 0)
goto out_postfail;
return 0;
out_err:
svc_rdma_send_error(rdma_xprt, p, ret);
svc_rdma_recv_ctxt_put(rdma_xprt, ctxt);
return 0;
out_postfail:
if (ret == -EINVAL)
svc_rdma_send_error(rdma_xprt, p, ret);
svc_rdma_recv_ctxt_put(rdma_xprt, ctxt);
return ret;
out_drop:
svc_rdma_recv_ctxt_put(rdma_xprt, ctxt);
return 0;
}