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|
// 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_sendto. This is called by the
* RPC server when an RPC Reply is ready to be transmitted to a client.
*
* The passed-in svc_rqst contains a struct xdr_buf which holds an
* XDR-encoded RPC Reply message. sendto must construct the RPC-over-RDMA
* transport header, post all Write WRs needed for this Reply, then post
* a Send WR conveying the transport header and the RPC message itself to
* the client.
*
* svc_rdma_sendto must fully transmit the Reply before returning, as
* the svc_rqst will be recycled as soon as sendto returns. Remaining
* resources referred to by the svc_rqst are also recycled at that time.
* Therefore any resources that must remain longer must be detached
* from the svc_rqst and released later.
*
* Page Management
*
* The I/O that performs Reply transmission is asynchronous, and may
* complete well after sendto returns. Thus pages under I/O must be
* removed from the svc_rqst before sendto returns.
*
* The logic here depends on Send Queue and completion ordering. Since
* the Send WR is always posted last, it will always complete last. Thus
* when it completes, it is guaranteed that all previous Write WRs have
* also completed.
*
* Write WRs are constructed and posted. Each Write segment gets its own
* svc_rdma_rw_ctxt, allowing the Write completion handler to find and
* DMA-unmap the pages under I/O for that Write segment. The Write
* completion handler does not release any pages.
*
* When the Send WR is constructed, it also gets its own svc_rdma_send_ctxt.
* The ownership of all of the Reply's pages are transferred into that
* ctxt, the Send WR is posted, and sendto returns.
*
* The svc_rdma_send_ctxt is presented when the Send WR completes. The
* Send completion handler finally releases the Reply's pages.
*
* This mechanism also assumes that completions on the transport's Send
* Completion Queue do not run in parallel. Otherwise a Write completion
* and Send completion running at the same time could release pages that
* are still DMA-mapped.
*
* Error Handling
*
* - If the Send WR is posted successfully, it will either complete
* successfully, or get flushed. Either way, the Send completion
* handler releases the Reply's pages.
* - If the Send WR cannot be not posted, the forward path releases
* the Reply's pages.
*
* This handles the case, without the use of page reference counting,
* where two different Write segments send portions of the same page.
*/
#include <linux/spinlock.h>
#include <asm/unaligned.h>
#include <rdma/ib_verbs.h>
#include <rdma/rdma_cm.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_send(struct ib_cq *cq, struct ib_wc *wc);
static inline struct svc_rdma_send_ctxt *
svc_rdma_next_send_ctxt(struct list_head *list)
{
return list_first_entry_or_null(list, struct svc_rdma_send_ctxt,
sc_list);
}
static struct svc_rdma_send_ctxt *
svc_rdma_send_ctxt_alloc(struct svcxprt_rdma *rdma)
{
struct svc_rdma_send_ctxt *ctxt;
dma_addr_t addr;
void *buffer;
size_t size;
int i;
size = sizeof(*ctxt);
size += rdma->sc_max_send_sges * sizeof(struct ib_sge);
ctxt = kmalloc(size, 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_TO_DEVICE);
if (ib_dma_mapping_error(rdma->sc_pd->device, addr))
goto fail2;
ctxt->sc_send_wr.next = NULL;
ctxt->sc_send_wr.wr_cqe = &ctxt->sc_cqe;
ctxt->sc_send_wr.sg_list = ctxt->sc_sges;
ctxt->sc_send_wr.send_flags = IB_SEND_SIGNALED;
ctxt->sc_cqe.done = svc_rdma_wc_send;
ctxt->sc_xprt_buf = buffer;
ctxt->sc_sges[0].addr = addr;
for (i = 0; i < rdma->sc_max_send_sges; i++)
ctxt->sc_sges[i].lkey = rdma->sc_pd->local_dma_lkey;
return ctxt;
fail2:
kfree(buffer);
fail1:
kfree(ctxt);
fail0:
return NULL;
}
/**
* svc_rdma_send_ctxts_destroy - Release all send_ctxt's for an xprt
* @rdma: svcxprt_rdma being torn down
*
*/
void svc_rdma_send_ctxts_destroy(struct svcxprt_rdma *rdma)
{
struct svc_rdma_send_ctxt *ctxt;
while ((ctxt = svc_rdma_next_send_ctxt(&rdma->sc_send_ctxts))) {
list_del(&ctxt->sc_list);
ib_dma_unmap_single(rdma->sc_pd->device,
ctxt->sc_sges[0].addr,
rdma->sc_max_req_size,
DMA_TO_DEVICE);
kfree(ctxt->sc_xprt_buf);
kfree(ctxt);
}
}
/**
* svc_rdma_send_ctxt_get - Get a free send_ctxt
* @rdma: controlling svcxprt_rdma
*
* Returns a ready-to-use send_ctxt, or NULL if none are
* available and a fresh one cannot be allocated.
*/
struct svc_rdma_send_ctxt *svc_rdma_send_ctxt_get(struct svcxprt_rdma *rdma)
{
struct svc_rdma_send_ctxt *ctxt;
spin_lock(&rdma->sc_send_lock);
ctxt = svc_rdma_next_send_ctxt(&rdma->sc_send_ctxts);
if (!ctxt)
goto out_empty;
list_del(&ctxt->sc_list);
spin_unlock(&rdma->sc_send_lock);
out:
ctxt->sc_send_wr.num_sge = 0;
ctxt->sc_cur_sge_no = 0;
ctxt->sc_page_count = 0;
return ctxt;
out_empty:
spin_unlock(&rdma->sc_send_lock);
ctxt = svc_rdma_send_ctxt_alloc(rdma);
if (!ctxt)
return NULL;
goto out;
}
/**
* svc_rdma_send_ctxt_put - Return send_ctxt to free list
* @rdma: controlling svcxprt_rdma
* @ctxt: object to return to the free list
*
* Pages left in sc_pages are DMA unmapped and released.
*/
void svc_rdma_send_ctxt_put(struct svcxprt_rdma *rdma,
struct svc_rdma_send_ctxt *ctxt)
{
struct ib_device *device = rdma
|