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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 /*
  * Copyright (c) 2006, 2019 Oracle and/or its affiliates. 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 <linux/ratelimit.h>
 
 #include "rds_single_path.h"
 #include "rds.h"
 #include "ib.h"
 #include "ib_mr.h"
 
 /*
  * Convert IB-specific error message to RDS error message and call core
  * completion handler.
  */
 static void rds_ib_send_complete(struct rds_message *rm,
                  int wc_status,
                  void (*complete)(struct rds_message *rm, int 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;
     }
     complete(rm, notify_status);
 }
 
 static void rds_ib_send_unmap_data(struct rds_ib_connection *ic,
                    struct rm_data_op *op,
                    int wc_status)
 {
     if (op->op_nents)
         ib_dma_unmap_sg(ic->i_cm_id->device,
                 op->op_sg, op->op_nents,
                 DMA_TO_DEVICE);
 }
 
 static void rds_ib_send_unmap_rdma(struct rds_ib_connection *ic,
                    struct rm_rdma_op *op,
                    int wc_status)
 {
     if (op->op_mapped) {
         ib_dma_unmap_sg(ic->i_cm_id->device,
                 op->op_sg, op->op_nents,
                 op->op_write ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
         op->op_mapped = 0;
     }
 
     /* 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,
      * we would need to take an event for the rdma WR. 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_complete(container_of(op, struct rds_message, rdma),
                  wc_status, rds_rdma_send_complete);
 
     if (op->op_write)
         rds_stats_add(s_send_rdma_bytes, op->op_bytes);
     else
         rds_stats_add(s_recv_rdma_bytes, op->op_bytes);
 }
 
 static void rds_ib_send_unmap_atomic(struct rds_ib_connection *ic,
                      struct rm_atomic_op *op,
                      int wc_status)
 {
     /* unmap atomic recvbuf */
     if (op->op_mapped) {
         ib_dma_unmap_sg(ic->i_cm_id->device, op->op_sg, 1,
                 DMA_FROM_DEVICE);
         op->op_mapped = 0;
     }
 
     rds_ib_send_complete(container_of(op, struct rds_message, atomic),
                  wc_status, rds_atomic_send_complete);
 
     if (op->op_type == RDS_ATOMIC_TYPE_CSWP)
         rds_ib_stats_inc(s_ib_atomic_cswp);
     else
         rds_ib_stats_inc(s_ib_atomic_fadd);
 }
 
 /*
  * Unmap the resources associated with a struct send_work.
  *
  * Returns the rm for no good reason other than it is unobtainable
  * other than by switching on wr.opcode, currently, and the caller,
  * the event handler, needs it.
  */
 static struct rds_message *rds_ib_send_unmap_op(struct rds_ib_connection *ic,
                         struct rds_ib_send_work *send,
                         int wc_status)
 {
     struct rds_message *rm = NULL;
 
     /* In the error case, wc.opcode sometimes contains garbage */
     switch (send->s_wr.opcode) {
     case IB_WR_SEND:
         if (send->s_op) {
             rm = container_of(send->s_op, struct rds_message, data);
             rds_ib_send_unmap_data(ic, send->s_op, wc_status);
         }
         break;
     case IB_WR_RDMA_WRITE:
     case IB_WR_RDMA_READ:
         if (send->s_op) {
             rm = container_of(send->s_op, struct rds_message, rdma);
             rds_ib_send_unmap_rdma(ic, send->s_op, wc_status);
         }
         break;
     case IB_WR_ATOMIC_FETCH_AND_ADD:
     case IB_WR_ATOMIC_CMP_AND_SWP:
         if (send->s_op) {
             rm = container_of(send->s_op, struct rds_message, atomic);
             rds_ib_send_unmap_atomic(ic, send->s_op, wc_status);
         }
         break;
     default:
         printk_ratelimited(KERN_NOTICE
                    "RDS/IB: %s: unexpected opcode 0x%x in WR!\n",
                    __func__, send->s_wr.opcode);
         break;
     }
 
     send->s_wr.opcode = 0xdead;
 
     return rm;
 }
 
 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_op = NULL;
 
         send->s_wr.wr_id = i;
         send->s_wr.sg_list = send->s_sge;
         send->s_wr.ex.imm_data = 0;
 
         sge = &send->s_sge[0];
         sge->addr = ic->i_send_hdrs_dma[i];
 
         sge->length = sizeof(struct rds_header);
         sge->lkey = ic->i_pd->local_dma_lkey;
 
         send->s_sge[1].lkey = ic->i_pd->local_dma_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_op && send->s_wr.opcode != 0xdead)
             rds_ib_send_unmap_op(ic, send, IB_WC_WR_FLUSH_ERR);
     }
 }
 
 /*
  * The only fast path caller always has a non-zero nr, so we don't
  * bother testing nr before performing the atomic sub.
  */
 static void rds_ib_sub_signaled(struct rds_ib_connection *ic, int nr)
 {
     if ((atomic_sub_return(nr, &ic->i_signaled_sends) == 0) &&
         waitqueue_active(&rds_ib_ring_empty_wait))
         wake_up(&rds_ib_ring_empty_wait);
     BUG_ON(atomic_read(&ic->i_signaled_sends) < 0);
 }
 
 /*
  * 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_cqe_handler(struct rds_ib_connection *ic, struct ib_wc *wc)
 {
     struct rds_message *rm = NULL;
     struct rds_connection *conn = ic->conn;
     struct rds_ib_send_work *send;
     u32 completed;
     u32 oldest;
     u32 i = 0;
     int nr_sig = 0;
 
 
     rdsdebug("wc wr_id 0x%llx status %u (%s) byte_len %u imm_data %u\n",
          (unsigned long long)wc->wr_id, wc->status,
          ib_wc_status_msg(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 (time_after(jiffies, ic->i_ack_queued + HZ / 2))
             rds_ib_stats_inc(s_ib_tx_stalled);
         rds_ib_ack_send_complete(ic);
         return;
     }
 
     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];
         if (send->s_wr.send_flags & IB_SEND_SIGNALED)
             nr_sig++;
 
         rm = rds_ib_send_unmap_op(ic, send, wc->status);
 
         if (time_after(jiffies, send->s_queued + HZ / 2))
             rds_ib_stats_inc(s_ib_tx_stalled);
 
         if (send->s_op) {
             if (send->s_op == rm->m_final_op) {
                 /* If anyone waited for this message to get
                  * flushed out, wake them up now
                  */
                 rds_message_unmapped(rm);
             }
             rds_message_put(rm);
             send->s_op = NULL;
         }
 
         oldest = (oldest + 1) % ic->i_send_ring.w_nr;
     }
 
     rds_ib_ring_free(&ic->i_send_ring, completed);
     rds_ib_sub_signaled(ic, nr_sig);
 
     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 <%pI6c,%pI6c,%d> had status %u (%s), vendor err 0x%x, disconnecting and reconnecting\n",
                   &conn->c_laddr, &conn->c_faddr,
                   conn->c_tos, wc->status,
                   ib_wc_status_msg(wc->status), wc->vendor_err);
     }
 }
 
 /*
  * 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 receiver'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
  * sets RDS_IN_XMIT 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("wanted=%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("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 int rds_ib_set_wr_signal_state(struct rds_ib_connection *ic,
                          struct rds_ib_send_work *send,
                          bool notify)
 {
     /*
      * 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 || notify) {
         ic->i_unsignaled_wrs = rds_ib_sysctl_max_unsig_wrs;
         send->s_wr.send_flags |= IB_SEND_SIGNALED;
         return 1;
     }
     return 0;
 }
 
 /*
  * 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;
     const struct ib_send_wr *failed_wr;
     struct scatterlist *scat;
     u32 pos;
     u32 i;
     u32 work_alloc;
     u32 credit_alloc = 0;
     u32 posted;
     u32 adv_credits = 0;
     int send_flags = 0;
     int bytes_sent = 0;
     int ret;
     int flow_controlled = 0;
     int nr_sig = 0;
 
     BUG_ON(off % RDS_FRAG_SIZE);
     BUG_ON(hdr_off != 0 && hdr_off != sizeof(struct rds_header));
 
     /* Do not send cong updates to IB loopback */
     if (conn->c_loopback
         && rm->m_inc.i_hdr.h_flags & RDS_FLAG_CONG_BITMAP) {
         rds_cong_map_updated(conn->c_fcong, ~(u64) 0);
         scat = &rm->data.op_sg[sg];
         ret = max_t(int, RDS_CONG_MAP_BYTES, scat->length);
         return sizeof(struct rds_header) + ret;
     }
 
     /* FIXME we may overallocate here */
     if (be32_to_cpu(rm->m_inc.i_hdr.h_len) == 0)
         i = 1;
     else
         i = DIV_ROUND_UP(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;
     }
 
     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 = 1;
         }
         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_data_op) {
         if (rm->data.op_nents) {
             rm->data.op_count = ib_dma_map_sg(dev,
                               rm->data.op_sg,
                               rm->data.op_nents,
                               DMA_TO_DEVICE);
             rdsdebug("ic %p mapping rm %p: %d\n", ic, rm, rm->data.op_count);
             if (rm->data.op_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->data.op_count = 0;
         }
 
         rds_message_addref(rm);
         rm->data.op_dmasg = 0;
         rm->data.op_dmaoff = 0;
         ic->i_data_op = &rm->data;
 
         /* 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->rdma.op_active) {
             struct rds_ext_header_rdma ext_hdr;
 
             ext_hdr.h_rdma_rkey = cpu_to_be32(rm->rdma.op_rkey);
             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.
          */
         if (ic->i_flowctl) {
             rds_ib_send_grab_credits(ic, 0, &posted, 1, RDS_MAX_ADV_CREDIT - adv_credits);
             adv_credits += posted;
             BUG_ON(adv_credits > 255);
         }
     }
 
     /* 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->rdma.op_active && rm->rdma.op_fence)
         send_flags = IB_SEND_FENCE;
 
     /* Each frag gets a header. Msgs may be 0 bytes */
     send = &ic->i_sends[pos];
     first = send;
     prev = NULL;
     scat = &ic->i_data_op->op_sg[rm->data.op_dmasg];
     i = 0;
     do {
         unsigned int len = 0;
 
         /* Set up the header */
         send->s_wr.send_flags = send_flags;
         send->s_wr.opcode = IB_WR_SEND;
         send->s_wr.num_sge = 1;
         send->s_wr.next = NULL;
         send->s_queued = jiffies;
         send->s_op = NULL;
 
         send->s_sge[0].addr = ic->i_send_hdrs_dma[pos];
 
         send->s_sge[0].length = sizeof(struct rds_header);
         send->s_sge[0].lkey = ic->i_pd->local_dma_lkey;
 
         ib_dma_sync_single_for_cpu(ic->rds_ibdev->dev,
                        ic->i_send_hdrs_dma[pos],
                        sizeof(struct rds_header),
                        DMA_TO_DEVICE);
         memcpy(ic->i_send_hdrs[pos], &rm->m_inc.i_hdr,
                sizeof(struct rds_header));
 
 
         /* Set up the data, if present */
         if (i < work_alloc
             && scat != &rm->data.op_sg[rm->data.op_count]) {
             len = min(RDS_FRAG_SIZE,
                   sg_dma_len(scat) - rm->data.op_dmaoff);
             send->s_wr.num_sge = 2;
 
             send->s_sge[1].addr = sg_dma_address(scat);
             send->s_sge[1].addr += rm->data.op_dmaoff;
             send->s_sge[1].length = len;
             send->s_sge[1].lkey = ic->i_pd->local_dma_lkey;
 
             bytes_sent += len;
             rm->data.op_dmaoff += len;
             if (rm->data.op_dmaoff == sg_dma_len(scat)) {
                 scat++;
                 rm->data.op_dmasg++;
                 rm->data.op_dmaoff = 0;
             }
         }
 
         rds_ib_set_wr_signal_state(ic, send, false);
 
         /*
          * Always signal the last one if we're stopping due to flow control.
          */
         if (ic->i_flowctl && flow_controlled && i == (work_alloc - 1)) {
             rds_ib_set_wr_signal_state(ic, send, true);
             send->s_wr.send_flags |= IB_SEND_SOLICITED;
         }
 
         if (send->s_wr.send_flags & IB_SEND_SIGNALED)
             nr_sig++;
 
         rdsdebug("send %p wr %p num_sge %u next %p\n", send,
              &send->s_wr, send->s_wr.num_sge, send->s_wr.next);
 
         if (ic->i_flowctl && 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);
         }
         ib_dma_sync_single_for_device(ic->rds_ibdev->dev,
                           ic->i_send_hdrs_dma[pos],
                           sizeof(struct rds_header),
                           DMA_TO_DEVICE);
 
         if (prev)
             prev->s_wr.next = &send->s_wr;
         prev = send;
 
         pos = (pos + 1) % ic->i_send_ring.w_nr;
         send = &ic->i_sends[pos];
         i++;
 
     } while (i < work_alloc
          && scat != &rm->data.op_sg[rm->data.op_count]);
 
     /* 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)
         bytes_sent += sizeof(struct rds_header);
 
     /* if we finished the message then send completion owns it */
     if (scat == &rm->data.op_sg[rm->data.op_count]) {
         prev->s_op = ic->i_data_op;
         prev->s_wr.send_flags |= IB_SEND_SOLICITED;
         if (!(prev->s_wr.send_flags & IB_SEND_SIGNALED))
             nr_sig += rds_ib_set_wr_signal_state(ic, prev, true);
         ic->i_data_op = NULL;
     }
 
     /* Put back wrs & credits we didn't use */
     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);
 
     if (nr_sig)
         atomic_add(nr_sig, &ic->i_signaled_sends);
 
     /* 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 %pI6c "
                "returned %d\n", &conn->c_faddr, ret);
         rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
         rds_ib_sub_signaled(ic, nr_sig);
         if (prev->s_op) {
             ic->i_data_op = prev->s_op;
             prev->s_op = NULL;
         }
 
         rds_ib_conn_error(ic->conn, "ib_post_send failed\n");
         goto out;
     }
 
     ret = bytes_sent;
 out:
     BUG_ON(adv_credits);
     return ret;
 }
 
 /*
  * Issue atomic operation.
  * A simplified version of the rdma case, we always map 1 SG, and
  * only 8 bytes, for the return value from the atomic operation.
  */
 int rds_ib_xmit_atomic(struct rds_connection *conn, struct rm_atomic_op *op)
 {
     struct rds_ib_connection *ic = conn->c_transport_data;
     struct rds_ib_send_work *send = NULL;
     const struct ib_send_wr *failed_wr;
     u32 pos;
     u32 work_alloc;
     int ret;
     int nr_sig = 0;
 
     work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, 1, &pos);
     if (work_alloc != 1) {
         rds_ib_stats_inc(s_ib_tx_ring_full);
         ret = -ENOMEM;
         goto out;
     }
 
     /* address of send request in ring */
     send = &ic->i_sends[pos];
     send->s_queued = jiffies;
 
     if (op->op_type == RDS_ATOMIC_TYPE_CSWP) {
         send->s_atomic_wr.wr.opcode = IB_WR_MASKED_ATOMIC_CMP_AND_SWP;
         send->s_atomic_wr.compare_add = op->op_m_cswp.compare;
         send->s_atomic_wr.swap = op->op_m_cswp.swap;
         send->s_atomic_wr.compare_add_mask = op->op_m_cswp.compare_mask;
         send->s_atomic_wr.swap_mask = op->op_m_cswp.swap_mask;
     } else { /* FADD */
         send->s_atomic_wr.wr.opcode = IB_WR_MASKED_ATOMIC_FETCH_AND_ADD;
         send->s_atomic_wr.compare_add = op->op_m_fadd.add;
         send->s_atomic_wr.swap = 0;
         send->s_atomic_wr.compare_add_mask = op->op_m_fadd.nocarry_mask;
         send->s_atomic_wr.swap_mask = 0;
     }
     send->s_wr.send_flags = 0;
     nr_sig = rds_ib_set_wr_signal_state(ic, send, op->op_notify);
     send->s_atomic_wr.wr.num_sge = 1;
     send->s_atomic_wr.wr.next = NULL;
     send->s_atomic_wr.remote_addr = op->op_remote_addr;
     send->s_atomic_wr.rkey = op->op_rkey;
     send->s_op = op;
     rds_message_addref(container_of(send->s_op, struct rds_message, atomic));
 
     /* map 8 byte retval buffer to the device */
     ret = ib_dma_map_sg(ic->i_cm_id->device, op->op_sg, 1, DMA_FROM_DEVICE);
     rdsdebug("ic %p mapping atomic op %p. mapped %d pg\n", ic, op, ret);
     if (ret != 1) {
         rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
         rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
         ret = -ENOMEM; /* XXX ? */
         goto out;
     }
 
     /* Convert our struct scatterlist to struct ib_sge */
     send->s_sge[0].addr = sg_dma_address(op->op_sg);
     send->s_sge[0].length = sg_dma_len(op->op_sg);
     send->s_sge[0].lkey = ic->i_pd->local_dma_lkey;
 
     rdsdebug("rva %Lx rpa %Lx len %u\n", op->op_remote_addr,
          send->s_sge[0].addr, send->s_sge[0].length);
 
     if (nr_sig)
         atomic_add(nr_sig, &ic->i_signaled_sends);
 
     failed_wr = &send->s_atomic_wr.wr;
     ret = ib_post_send(ic->i_cm_id->qp, &send->s_atomic_wr.wr, &failed_wr);
     rdsdebug("ic %p send %p (wr %p) ret %d wr %p\n", ic,
          send, &send->s_atomic_wr, ret, failed_wr);
     BUG_ON(failed_wr != &send->s_atomic_wr.wr);
     if (ret) {
         printk(KERN_WARNING "RDS/IB: atomic ib_post_send to %pI6c "
                "returned %d\n", &conn->c_faddr, ret);
         rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
         rds_ib_sub_signaled(ic, nr_sig);
         goto out;
     }
 
     if (unlikely(failed_wr != &send->s_atomic_wr.wr)) {
         printk(KERN_WARNING "RDS/IB: atomic ib_post_send() rc=%d, but failed_wqe updated!\n", ret);
         BUG_ON(failed_wr != &send->s_atomic_wr.wr);
     }
 
 out:
     return ret;
 }
 
 int rds_ib_xmit_rdma(struct rds_connection *conn, struct rm_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;
     const struct ib_send_wr *failed_wr;
     struct scatterlist *scat;
     unsigned long len;
     u64 remote_addr = op->op_remote_addr;
     u32 max_sge = ic->rds_ibdev->max_sge;
     u32 pos;
     u32 work_alloc;
     u32 i;
     u32 j;
     int sent;
     int ret;
     int num_sge;
     int nr_sig = 0;
     u64 odp_addr = op->op_odp_addr;
     u32 odp_lkey = 0;
 
     /* map the op the first time we see it */
     if (!op->op_odp_mr) {
         if (!op->op_mapped) {
             op->op_count =
                 ib_dma_map_sg(ic->i_cm_id->device, op->op_sg,
                           op->op_nents,
                           (op->op_write) ? DMA_TO_DEVICE :
                                    DMA_FROM_DEVICE);
             rdsdebug("ic %p mapping op %p: %d\n", ic, op,
                  op->op_count);
             if (op->op_count == 0) {
                 rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
                 ret = -ENOMEM; /* XXX ? */
                 goto out;
             }
             op->op_mapped = 1;
         }
     } else {
         op->op_count = op->op_nents;
         odp_lkey = rds_ib_get_lkey(op->op_odp_mr->r_trans_private);
     }
 
     /*
      * 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 = DIV_ROUND_UP(op->op_count, 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->op_sg[0];
     sent = 0;
     num_sge = op->op_count;
 
     for (i = 0; i < work_alloc && scat != &op->op_sg[op->op_count]; i++) {
         send->s_wr.send_flags = 0;
         send->s_queued = jiffies;
         send->s_op = NULL;
 
         if (!op->op_notify)
             nr_sig += rds_ib_set_wr_signal_state(ic, send,
                                  op->op_notify);
 
         send->s_wr.opcode = op->op_write ? IB_WR_RDMA_WRITE : IB_WR_RDMA_READ;
         send->s_rdma_wr.remote_addr = remote_addr;
         send->s_rdma_wr.rkey = op->op_rkey;
 
         if (num_sge > max_sge) {
             send->s_rdma_wr.wr.num_sge = max_sge;
             num_sge -= max_sge;
         } else {
             send->s_rdma_wr.wr.num_sge = num_sge;
         }
 
         send->s_rdma_wr.wr.next = NULL;
 
         if (prev)
             prev->s_rdma_wr.wr.next = &send->s_rdma_wr.wr;
 
         for (j = 0; j < send->s_rdma_wr.wr.num_sge &&
              scat != &op->op_sg[op->op_count]; j++) {
             len = sg_dma_len(scat);
             if (!op->op_odp_mr) {
                 send->s_sge[j].addr = sg_dma_address(scat);
                 send->s_sge[j].lkey = ic->i_pd->local_dma_lkey;
             } else {
                 send->s_sge[j].addr = odp_addr;
                 send->s_sge[j].lkey = odp_lkey;
             }
             send->s_sge[j].length = len;
 
             sent += len;
             rdsdebug("ic %p sent %d remote_addr %llu\n", ic, sent, remote_addr);
 
             remote_addr += len;
             odp_addr += len;
             scat++;
         }
 
         rdsdebug("send %p wr %p num_sge %u next %p\n", send,
             &send->s_rdma_wr.wr,
             send->s_rdma_wr.wr.num_sge,
             send->s_rdma_wr.wr.next);
 
         prev = send;
         if (++send == &ic->i_sends[ic->i_send_ring.w_nr])
             send = ic->i_sends;
     }
 
     /* give a reference to the last op */
     if (scat == &op->op_sg[op->op_count]) {
         prev->s_op = op;
         rds_message_addref(container_of(op, struct rds_message, rdma));
     }
 
     if (i < work_alloc) {
         rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - i);
         work_alloc = i;
     }
 
     if (nr_sig)
         atomic_add(nr_sig, &ic->i_signaled_sends);
 
     failed_wr = &first->s_rdma_wr.wr;
     ret = ib_post_send(ic->i_cm_id->qp, &first->s_rdma_wr.wr, &failed_wr);
     rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic,
          first, &first->s_rdma_wr.wr, ret, failed_wr);
     BUG_ON(failed_wr != &first->s_rdma_wr.wr);
     if (ret) {
         printk(KERN_WARNING "RDS/IB: rdma ib_post_send to %pI6c "
                "returned %d\n", &conn->c_faddr, ret);
         rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
         rds_ib_sub_signaled(ic, nr_sig);
         goto out;
     }
 
     if (unlikely(failed_wr != &first->s_rdma_wr.wr)) {
         printk(KERN_WARNING "RDS/IB: ib_post_send() rc=%d, but failed_wqe updated!\n", ret);
         BUG_ON(failed_wr != &first->s_rdma_wr.wr);
     }
 
 
 out:
     return ret;
 }
 
 void rds_ib_xmit_path_complete(struct rds_conn_path *cp)
 {
     struct rds_connection *conn = cp->cp_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);
 }

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