/*
* Copyright (c) 2006 Oracle. 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
* OpenIB.org BSD 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.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*
*/
#include <linux/kernel.h>
#include <linux/in.h>
#include <linux/device.h>
#include <linux/dmapool.h>
#include "rds.h"
#include "rdma.h"
#include "ib.h"
static void rds_ib_send_rdma_complete(struct rds_message *rm,
int wc_status)
{
int notify_status;
switch (wc_status) {
case IB_WC_WR_FLUSH_ERR:
return;
case IB_WC_SUCCESS:
notify_status = RDS_RDMA_SUCCESS;
break;
case IB_WC_REM_ACCESS_ERR:
notify_status = RDS_RDMA_REMOTE_ERROR;
break;
default:
notify_status = RDS_RDMA_OTHER_ERROR;
break;
}
rds_rdma_send_complete(rm, notify_status);
}
static void rds_ib_send_unmap_rdma(struct rds_ib_connection *ic,
struct rds_rdma_op *op)
{
if (op->r_mapped) {
ib_dma_unmap_sg(ic->i_cm_id->device,
op->r_sg, op->r_nents,
op->r_write ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
op->r_mapped = 0;
}
}
static void rds_ib_send_unmap_rm(struct rds_ib_connection *ic,
struct rds_ib_send_work *send,
int wc_status)
{
struct rds_message *rm = send->s_rm;
rdsdebug("ic %p send %p rm %p\n", ic, send, rm);
ib_dma_unmap_sg(ic->i_cm_id->device,
rm->m_sg, rm->m_nents,
DMA_TO_DEVICE);
if (rm->m_rdma_op != NULL) {
rds_ib_send_unmap_rdma(ic, rm->m_rdma_op);
/* If the user asked for a completion notification on this
* message, we can implement three different semantics:
* 1. Notify when we received the ACK on the RDS message
* that was queued with the RDMA. This provides reliable
* notification of RDMA status at the expense of a one-way
* packet delay.
* 2. Notify when the IB stack gives us the completion event for
* the RDMA operation.
* 3. Notify when the IB stack gives us the completion event for
* the accompanying RDS messages.
* Here, we implement approach #3. To implement approach #2,
* call rds_rdma_send_complete from the cq_handler. To implement #1,
* don't call rds_rdma_send_complete at all, and fall back to the notify
* handling in the ACK processing code.
*
* Note: There's no need to explicitly sync any RDMA buffers using
* ib_dma_sync_sg_for_cpu - the completion for the RDMA
* operation itself unmapped the RDMA buffers, which takes care
* of synching.
*/
rds_ib_send_rdma_complete(rm, wc_status);
if (rm->m_rdma_op->r_write)
rds_stats_add(s_send_rdma_bytes, rm->m_rdma_op->r_bytes);
else
rds_stats_add(s_recv_rdma_bytes, rm->m_rdma_op->r_bytes);
}
/* If anyone waited for this message to get flushed out, wake
* them up now */
rds_message_unmapped(rm);
rds_message_put(rm);
send->s_rm = NULL;
}
void rds_ib_send_init_ring(struct rds_ib_connection *ic)
{
struct rds_ib_send_work *send;
u32 i;
for (i = 0, send = ic->i_sends; i < ic->i_send_ring.w_nr; i++, send++) {
struct ib_sge *sge;
send->s_rm = NULL;
send->s_op = NULL;
send->s_wr.wr_id = i;
send->s_wr.sg_list = send->s_sge;
send->s_wr.num_sge = 1;
send->s_wr.opcode = IB_WR_SEND;
send->s_wr.send_flags = 0;
send->s_wr.ex.imm_data = 0;
sge = rds_ib_data_sge(ic, send->s_sge);
sge->lkey = ic->i_mr->lkey;
sge = rds_ib_header_sge(ic, send->s_sge);
sge->addr = ic->i_send_hdrs_dma + (i * sizeof(struct rds_header));
sge->length = sizeof(struct rds_header);
sge->lkey = ic->i_mr->lkey;
}
}
void rds_ib_send_clear_ring(struct rds_ib_connection *ic)
{
struct rds_ib_send_work *send;
u32 i;
for (i = 0, send = ic->i_sends; i < ic->i_send_ring.w_nr; i++, send++) {
if (send->s_wr.opcode == 0xdead)
continue;
if (send->s_rm)
rds_ib_send_unmap_rm(ic, send, IB_WC_WR_FLUSH_ERR);
if (send->s_op)
rds_ib_send_unmap_rdma(ic, send->s_op);
}
}
/*
* The _oldest/_free ring operations here race cleanly with the alloc/unalloc
* operations performed in the send path. As the sender allocs and potentially
* unallocs the next free entry in the ring it doesn't alter which is
* the next to be freed, which is what this is concerned with.
*/
void rds_ib_send_cq_comp_handler(struct ib_cq *cq, void *context)
{
struct rds_connection *conn = context;
struct rds_ib_connection *ic = conn->c_transport_data;
struct ib_wc wc;
struct rds_ib_send_work *send;
u32 completed;
u32 oldest;
u32 i = 0;
int ret;
rdsdebug("cq %p conn %p\n", cq, conn);
rds_ib_stats_inc(s_ib_tx_cq_call);
ret = ib_req_notify_cq(cq, IB_CQ_NEXT_COMP);
if (ret)
rdsdebug("ib_req_notify_cq send failed: %d\n", ret);
while (ib_poll_cq(cq, 1, &wc) > 0) {
rdsdebug("wc wr_id 0x%llx status %u byte_len %u imm_data %u\n",
(unsigned long long)wc.wr_id, wc.status, wc.byte_len,
be32_to_cpu(wc.ex.imm_data));
rds_ib_stats_inc(s_ib_tx_cq_event);
if (wc.wr_id == RDS_IB_ACK_WR_ID) {
if (ic->i_ack_queued + HZ/2 < jiffies)
rds_ib_stats_inc(s_ib_tx_stalled);
rds_ib_ack_send_complete(ic);
continue;
}
oldest = rds_ib_ring_oldest(&ic->i_send_ring);
completed = rds_ib_ring_completed(&ic->i_send_ring, wc.wr_id, oldest);
for (i = 0; i < completed; i++) {
send = &ic->i_sends[oldest];
/* In the error case, wc.opcode sometimes contains garbage */
switch (send->s_wr.opcode) {
case IB_WR_SEND:
if (send->s_rm)
rds_ib_send_unmap_rm(ic, send, wc.status);
break;
case IB_WR_RDMA_WRITE:
case IB_WR_RDMA_READ:
/* Nothing to be done - the SG list will be unmapped
* when the SEND completes. */
break;
default:
if (printk_ratelimit())
printk(KERN_NOTICE
"RDS/IB: %s: unexpected opcode 0x%x in WR!\n",
__func__, send->s_wr.opcode);
break;
}
send->s_wr.opcode = 0xdead;
send->s_wr.num_sge = 1;
if (send->s_queued + HZ/2 < jiffies)
rds_ib_stats_inc(s_ib_tx_stalled);
/* If a RDMA operation produced an error, signal this right
* away. If we don't, the subsequent SEND that goes with this
* RDMA will be canceled with ERR_WFLUSH, and the application
* never learn that the RDMA failed. */
if (unlikely(wc.status == IB_WC_REM_ACCESS_ERR && send->s_op)) {
struct rds_message *rm;
rm = rds_send_get_message(conn, send->s_op);
if (rm)
rds_ib_send_rdma_complete(rm, wc.status);
}
oldest = (oldest + 1) % ic->i_send_ring.w_nr;
}
rds_ib_ring_free(&ic->i_send_ring, completed);
if (test_and_clear_bit(RDS_LL_SEND_FULL, &conn->c_flags) ||
test_bit(0, &conn->c_map_queued))
queue_delayed_work(rds_wq, &conn->c_send_w, 0);
/* We expect errors as the qp is drained during shutdown */
if (wc.status != IB_WC_SUCCESS && rds_conn_up(conn)) {
rds_ib_conn_error(conn,
"send completion on %pI4 "
"had status %u, disconnecting and reconnecting\n",
&conn->c_faddr, wc.status);
}
}
}
/*
* This is the main function for allocating credits when sending
* messages.
*
* Conceptually, we have two counters:
* - send credits: this tells us how many WRs we're allowed
* to submit without overruning the reciever's queue. For
* each SEND WR we post, we decrement this by one.
*
* - posted credits: this tells us how many WRs we recently
* posted to the receive queue. This value is transferred
* to the peer as a "credit update" in a RDS header field.
* Every time we transmit credits to the peer, we subtract
* the amount of transferred credits from this counter.
*
* It is essential that we avoid situations where both sides have
* exhausted their send credits, and are unable to send new credits
* to the peer. We achieve this by requiring that we send at least
* one credit update to the peer before exhausting our credits.
* When new credits arrive, we subtract one credit that is withheld
* until we've posted new buffers and are ready to transmit these
* credits (see rds_ib_send_add_credits below).
*
* The RDS send code is essentially single-threaded; rds_send_xmit
* grabs c_send_lock to ensure exclusive access to the send ring.
* However, the ACK sending code is independent and can race with
* message SENDs.
*
* In the send path, we need to update the counters for send credits
* and the counter of posted buffers atomically - when we use the
* last available credit, we cannot allow another thread to race us
* and grab the posted credits counter. Hence, we have to use a
* spinlock to protect the credit counter, or use atomics.
*
* Spinlocks shared between the send and the receive path are bad,
* because they create unnecessary delays. An early implementation
* using a spinlock showed a 5% degradation in throughput at some
* loads.
*
* This implementation avoids spinlocks completely, putting both
* counters into a single atomic, and updating that atomic using
* atomic_add (in the receive path, when receiving fresh credits),
* and using atomic_cmpxchg when updating the two counters.
*/
int rds_ib_send_grab_credits(struct rds_ib_connection *ic,
u32 wanted, u32 *adv_credits, int need_posted, int max_posted)
{
unsigned int avail, posted, got = 0, advertise;
long oldval, newval;
*adv_credits = 0;
if (!ic->i_flowctl)
return wanted;
try_again:
advertise = 0;
oldval = newval = atomic_read(&ic->i_credits);
posted = IB_GET_POST_CREDITS(oldval);
avail = IB_GET_SEND_CREDITS(oldval);
rdsdebug("rds_ib_send_grab_credits(%u): credits=%u posted=%u\n",
wanted, avail, posted);
/* The last credit must be used to send a credit update. */
if (avail && !posted)
avail--;
if (avail < wanted) {
struct rds_connection *conn = ic->i_cm_id->context;
/* Oops, there aren't that many credits left! */
set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
got = avail;
} else {
/* Sometimes you get what you want, lalala. */
got = wanted;
}
newval -= IB_SET_SEND_CREDITS(got);
/*
* If need_posted is non-zero, then the caller wants
* the posted regardless of whether any send credits are
* available.
*/
if (posted && (got || need_posted)) {
advertise = min_t(unsigned int, posted, max_posted);
newval -= IB_SET_POST_CREDITS(advertise);
}
/* Finally bill everything */
if (atomic_cmpxchg(&ic->i_credits, oldval, newval) != oldval)
goto try_again;
*adv_credits = advertise;
return got;
}
void rds_ib_send_add_credits(struct rds_connection *conn, unsigned int credits)
{
struct rds_ib_connection *ic = conn->c_transport_data;
if (credits == 0)
return;
rdsdebug("rds_ib_send_add_credits(%u): current=%u%s\n",
credits,
IB_GET_SEND_CREDITS(atomic_read(&ic->i_credits)),
test_bit(RDS_LL_SEND_FULL, &conn->c_flags) ? ", ll_send_full" : "");
atomic_add(IB_SET_SEND_CREDITS(credits), &ic->i_credits);
if (test_and_clear_bit(RDS_LL_SEND_FULL, &conn->c_flags))
queue_delayed_work(rds_wq, &conn->c_send_w, 0);
WARN_ON(IB_GET_SEND_CREDITS(credits) >= 16384);
rds_ib_stats_inc(s_ib_rx_credit_updates);
}
void rds_ib_advertise_credits(struct rds_connection *conn, unsigned int posted)
{
struct rds_ib_connection *ic = conn->c_transport_data;
if (posted == 0)
return;
atomic_add(IB_SET_POST_CREDITS(posted), &ic->i_credits);
/* Decide whether to send an update to the peer now.
* If we would send a credit update for every single buffer we
* post, we would end up with an ACK storm (ACK arrives,
* consumes buffer, we refill the ring, send ACK to remote
* advertising the newly posted buffer... ad inf)
*
* Performance pretty much depends on how often we send
* credit updates - too frequent updates mean lots of ACKs.
* Too infrequent updates, and the peer will run out of
* credits and has to throttle.
* For the time being, 16 seems to be a good compromise.
*/
if (IB_GET_POST_CREDITS(atomic_read(&ic->i_credits)) >= 16)
set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
}
static inline void
rds_ib_xmit_populate_wr(struct rds_ib_connection *ic,
struct rds_ib_send_work *send, unsigned int pos,
unsigned long buffer, unsigned int length,
int send_flags)
{
struct ib_sge *sge;
WARN_ON(pos != send - ic->i_sends);
send->s_wr.send_flags = send_flags;
send->s_wr.opcode = IB_WR_SEND;
send->s_wr.num_sge = 2;
send->s_wr.next = NULL;
send->s_queued = jiffies;
send->s_op = NULL;
if (length != 0) {
sge = rds_ib_data_sge(ic, send->s_sge);
sge->addr = buffer;
sge->length = length;
sge->lkey = ic->i_mr->lkey;
sge = rds_ib_header_sge(ic, send->s_sge);
} else {
/* We're sending a packet with no payload. There is only
* one SGE */
send->s_wr.num_sge = 1;
sge = &send->s_sge[0];
}
sge->addr = ic->i_send_hdrs_dma + (pos * sizeof(struct rds_header));
sge->length = sizeof(struct rds_header);
sge->lkey = ic->i_mr->lkey;
}
/*
* This can be called multiple times for a given message. The first time
* we see a message we map its scatterlist into the IB device so that
* we can provide that mapped address to the IB scatter gather entries
* in the IB work requests. We translate the scatterlist into a series
* of work requests that fragment the message. These work requests complete
* in order so we pass ownership of the message to the completion handler
* once we send the final fragment.
*
* The RDS core uses the c_send_lock to only enter this function once
* per connection. This makes sure that the tx ring alloc/unalloc pairs
* don't get out of sync and confuse the ring.
*/
int rds_ib_xmit(struct rds_connection *conn, struct rds_message *rm,
unsigned int hdr_off, unsigned int sg, unsigned int off)
{
struct rds_ib_connection *ic = conn->c_transport_data;
struct ib_device *dev = ic->i_cm_id->device;
struct rds_ib_send_work *send = NULL;
struct rds_ib_send_work *first;
struct rds_ib_send_work *prev;
struct ib_send_wr *failed_wr;
struct scatterlist *scat;
u32 pos;
u32 i;
u32 work_alloc;
u32 credit_alloc;
u32 posted;
u32 adv_credits = 0;
int send_flags = 0;
int sent;
int ret;
int flow_controlled = 0;
BUG_ON(off % RDS_FRAG_SIZE);
BUG_ON(hdr_off != 0 && hdr_off != sizeof(struct rds_header));
/* FIXME we may overallocate here */
if (be32_to_cpu(rm->m_inc.i_hdr.h_len) == 0)
i = 1;
else
i = ceil(be32_to_cpu(rm->m_inc.i_hdr.h_len), RDS_FRAG_SIZE);
work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, i, &pos);
if (work_alloc == 0) {
set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
rds_ib_stats_inc(s_ib_tx_ring_full);
ret = -ENOMEM;
goto out;
}
credit_alloc = work_alloc;
if (ic->i_flowctl) {
credit_alloc = rds_ib_send_grab_credits(ic, work_alloc, &posted, 0, RDS_MAX_ADV_CREDIT);
adv_credits += posted;
if (credit_alloc < work_alloc) {
rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - credit_alloc);
work_alloc = credit_alloc;
flow_controlled++;
}
if (work_alloc == 0) {
set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
rds_ib_stats_inc(s_ib_tx_throttle);
ret = -ENOMEM;
goto out;
}
}
/* map the message the first time we see it */
if (ic->i_rm == NULL) {
/*
printk(KERN_NOTICE "rds_ib_xmit prep msg dport=%u flags=0x%x len=%d\n",
be16_to_cpu(rm->m_inc.i_hdr.h_dport),
rm->m_inc.i_hdr.h_flags,
be32_to_cpu(rm->m_inc.i_hdr.h_len));
*/
if (rm->m_nents) {
rm->m_count = ib_dma_map_sg(dev,
rm->m_sg, rm->m_nents, DMA_TO_DEVICE);
rdsdebug("ic %p mapping rm %p: %d\n", ic, rm, rm->m_count);
if (rm->m_count == 0) {
rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
ret = -ENOMEM; /* XXX ? */
goto out;
}
} else {
rm->m_count = 0;
}
ic->i_unsignaled_wrs = rds_ib_sysctl_max_unsig_wrs;
ic->i_unsignaled_bytes = rds_ib_sysctl_max_unsig_bytes;
rds_message_addref(rm);
ic->i_rm = rm;
/* Finalize the header */
if (test_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags))
rm->m_inc.i_hdr.h_flags |= RDS_FLAG_ACK_REQUIRED;
if (test_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags))
rm->m_inc.i_hdr.h_flags |= RDS_FLAG_RETRANSMITTED;
/* If it has a RDMA op, tell the peer we did it. This is
* used by the peer to release use-once RDMA MRs. */
if (rm->m_rdma_op) {
struct rds_ext_header_rdma ext_hdr;
ext_hdr.h_rdma_rkey = cpu_to_be32(rm->m_rdma_op->r_key);
rds_message_add_extension(&rm->m_inc.i_hdr,
RDS_EXTHDR_RDMA, &ext_hdr, sizeof(ext_hdr));
}
if (rm->m_rdma_cookie) {
rds_message_add_rdma_dest_extension(&rm->m_inc.i_hdr,
rds_rdma_cookie_key(rm->m_rdma_cookie),
rds_rdma_cookie_offset(rm->m_rdma_cookie));
}
/* Note - rds_ib_piggyb_ack clears the ACK_REQUIRED bit, so
* we should not do this unless we have a chance of at least
* sticking the header into the send ring. Which is why we
* should call rds_ib_ring_alloc first. */
rm->m_inc.i_hdr.h_ack = cpu_to_be64(rds_ib_piggyb_ack(ic));
rds_message_make_checksum(&rm->m_inc.i_hdr);
/*
* Update adv_credits since we reset the ACK_REQUIRED bit.
*/
rds_ib_send_grab_credits(ic, 0, &posted, 1, RDS_MAX_ADV_CREDIT - adv_credits);
adv_credits += posted;
BUG_ON(adv_credits > 255);
} else if (ic->i_rm != rm)
BUG();
send = &ic->i_sends[pos];
first = send;
prev = NULL;
scat = &rm->m_sg[sg];
sent = 0;
i = 0;
/* Sometimes you want to put a fence between an RDMA
* READ and the following SEND.
* We could either do this all the time
* or when requested by the user. Right now, we let
* the application choose.
*/
if (rm->m_rdma_op && rm->m_rdma_op->r_fence)
send_flags = IB_SEND_FENCE;
/*
* We could be copying the header into the unused tail of the page.
* That would need to be changed in the future when those pages might
* be mapped userspace pages or page cache pages. So instead we always
* use a second sge and our long-lived ring of mapped headers. We send
* the header after the data so that the data payload can be aligned on
* the receiver.
*/
/* handle a 0-len message */
if (be32_to_cpu(rm->m_inc.i_hdr.h_len) == 0) {
rds_ib_xmit_populate_wr(ic, send, pos, 0, 0, send_flags);
goto add_header;
}
/* if there's data reference it with a chain of work reqs */
for (; i < work_alloc && scat != &rm->m_sg[rm->m_count]; i++) {
unsigned int len;
send = &ic->i_sends[pos];
len = min(RDS_FRAG_SIZE, ib_sg_dma_len(dev, scat) - off);
rds_ib_xmit_populate_wr(ic, send, pos,
ib_sg_dma_address(dev, scat) + off, len,
send_flags);
/*
* We want to delay signaling completions just enough to get
* the batching benefits but not so much that we create dead time
* on the wire.
*/
if (ic->i_unsignaled_wrs-- == 0) {
ic->i_unsignaled_wrs = rds_ib_sysctl_max_unsig_wrs;
send->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED;
}
ic->i_unsignaled_bytes -= len;
if (ic->i_unsignaled_bytes <= 0) {
ic->i_unsignaled_bytes = rds_ib_sysctl_max_unsig_bytes;
send->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED;
}
/*
* Always signal the last one if we're stopping due to flow control.
*/
if (flow_controlled && i == (work_alloc-1))
send->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED;
rdsdebug("send %p wr %p num_sge %u next %p\n", send,
&send->s_wr, send->s_wr.num_sge, send->s_wr.next);
sent += len;
off += len;
if (off == ib_sg_dma_len(dev, scat)) {
scat++;
off = 0;
}
add_header:
/* Tack on the header after the data. The header SGE should already
* have been set up to point to the right header buffer. */
memcpy(&ic->i_send_hdrs[pos], &rm->m_inc.i_hdr, sizeof(struct rds_header));
if (0) {
struct rds_header *hdr = &ic->i_send_hdrs[pos];
printk(KERN_NOTICE "send WR dport=%u flags=0x%x len=%d\n",
be16_to_cpu(hdr->h_dport),
hdr->h_flags,
be32_to_cpu(hdr->h_len));
}
if (adv_credits) {
struct rds_header *hdr = &ic->i_send_hdrs[pos];
/* add credit and redo the header checksum */
hdr->h_credit = adv_credits;
rds_message_make_checksum(hdr);
adv_credits = 0;
rds_ib_stats_inc(s_ib_tx_credit_updates);
}
if (prev)
prev->s_wr.next = &send->s_wr;
prev = send;
pos = (pos + 1) % ic->i_send_ring.w_nr;
}
/* Account the RDS header in the number of bytes we sent, but just once.
* The caller has no concept of fragmentation. */
if (hdr_off == 0)
sent += sizeof(struct rds_header);
/* if we finished the message then send completion owns it */
if (scat == &rm->m_sg[rm->m_count]) {
prev->s_rm = ic->i_rm;
prev->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED;
ic->i_rm = NULL;
}
if (i < work_alloc) {
rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - i);
work_alloc = i;
}
if (ic->i_flowctl && i < credit_alloc)
rds_ib_send_add_credits(conn, credit_alloc - i);
/* XXX need to worry about failed_wr and partial sends. */
failed_wr = &first->s_wr;
ret = ib_post_send(ic->i_cm_id->qp, &first->s_wr, &failed_wr);
rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic,
first, &first->s_wr, ret, failed_wr);
BUG_ON(failed_wr != &first->s_wr);
if (ret) {
printk(KERN_WARNING "RDS/IB: ib_post_send to %pI4 "
"returned %d\n", &conn->c_faddr, ret);
rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
if (prev->s_rm) {
ic->i_rm = prev->s_rm;
prev->s_rm = NULL;
}
/* Finesse this later */
BUG();
goto out;
}
ret = sent;
out:
BUG_ON(adv_credits);
return ret;
}
int rds_ib_xmit_rdma(struct rds_connection *conn, struct rds_rdma_op *op)
{
struct rds_ib_connection *ic = conn->c_transport_data;
struct rds_ib_send_work *send = NULL;
struct rds_ib_send_work *first;
struct rds_ib_send_work *prev;
struct ib_send_wr *failed_wr;
struct rds_ib_device *rds_ibdev;
struct scatterlist *scat;
unsigned long len;
u64 remote_addr = op->r_remote_addr;
u32 pos;
u32 work_alloc;
u32 i;
u32 j;
int sent;
int ret;
int num_sge;
rds_ibdev = ib_get_client_data(ic->i_cm_id->device, &rds_ib_client);
/* map the message the first time we see it */
if (!op->r_mapped) {
op->r_count = ib_dma_map_sg(ic->i_cm_id->device,
op->r_sg, op->r_nents, (op->r_write) ?
DMA_TO_DEVICE : DMA_FROM_DEVICE);
rdsdebug("ic %p mapping op %p: %d\n", ic, op, op->r_count);
if (op->r_count == 0) {
rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
ret = -ENOMEM; /* XXX ? */
goto out;
}
op->r_mapped = 1;
}
/*
* Instead of knowing how to return a partial rdma read/write we insist that there
* be enough work requests to send the entire message.
*/
i = ceil(op->r_count, rds_ibdev->max_sge);
work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, i, &pos);
if (work_alloc != i) {
rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
rds_ib_stats_inc(s_ib_tx_ring_full);
ret = -ENOMEM;
goto out;
}
send = &ic->i_sends[pos];
first = send;
prev = NULL;
scat = &op->r_sg[0];
sent = 0;
num_sge = op->r_count;
for (i = 0; i < work_alloc && scat != &op->r_sg[op->r_count]; i++) {
send->s_wr.send_flags = 0;
send->s_queued = jiffies;
/*
* We want to delay signaling completions just enough to get
* the batching benefits but not so much that we create dead time on the wire.
*/
if (ic->i_unsignaled_wrs-- == 0) {
ic->i_unsignaled_wrs = rds_ib_sysctl_max_unsig_wrs;
send->s_wr.send_flags = IB_SEND_SIGNALED;
}
send->s_wr.opcode = op->r_write ? IB_WR_RDMA_WRITE : IB_WR_RDMA_READ;
send->s_wr.wr.rdma.remote_addr = remote_addr;
send->s_wr.wr.rdma.rkey = op->r_key;
send->s_op = op;
if (num_sge > rds_ibdev->max_sge) {
send->s_wr.num_sge = rds_ibdev->max_sge;
num_sge -= rds_ibdev->max_sge;
} else {
send->s_wr.num_sge = num_sge;
}
send->s_wr.next = NULL;
if (prev)
prev->s_wr.next = &send->s_wr;
for (j = 0; j < send->s_wr.num_sge && scat != &op->r_sg[op->r_count]; j++) {
len = ib_sg_dma_len(ic->i_cm_id->device, scat);
send->s_sge[j].addr =
ib_sg_dma_address(ic->i_cm_id->device, scat);
send->s_sge[j].length = len;
send->s_sge[j].lkey = ic->i_mr->lkey;
sent += len;
rdsdebug("ic %p sent %d remote_addr %llu\n", ic, sent, remote_addr);
remote_addr += len;
scat++;
}
rdsdebug("send %p wr %p num_sge %u next %p\n", send,
&send->s_wr, send->s_wr.num_sge, send->s_wr.next);
prev = send;
if (++send == &ic->i_sends[ic->i_send_ring.w_nr])
send = ic->i_sends;
}
/* if we finished the message then send completion owns it */
if (scat == &op->r_sg[op->r_count])
prev->s_wr.send_flags = IB_SEND_SIGNALED;
if (i < work_alloc) {
rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - i);
work_alloc = i;
}
failed_wr = &first->s_wr;
ret = ib_post_send(ic->i_cm_id->qp, &first->s_wr, &failed_wr);
rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic,
first, &first->s_wr, ret, failed_wr);
BUG_ON(failed_wr != &first->s_wr);
if (ret) {
printk(KERN_WARNING "RDS/IB: rdma ib_post_send to %pI4 "
"returned %d\n", &conn->c_faddr, ret);
rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
goto out;
}
if (unlikely(failed_wr != &first->s_wr)) {
printk(KERN_WARNING "RDS/IB: ib_post_send() rc=%d, but failed_wqe updated!\n", ret);
BUG_ON(failed_wr != &first->s_wr);
}
out:
return ret;
}
void rds_ib_xmit_complete(struct rds_connection *conn)
{
struct rds_ib_connection *ic = conn->c_transport_data;
/* We may have a pending ACK or window update we were unable
* to send previously (due to flow control). Try again. */
rds_ib_attempt_ack(ic);
}
