RDS: Implement silent atomics

Signed-off-by: Andy Grover <andy.grover@oracle.com>

5 files changed, 45 insertions, 35 deletions

diff --git a/net/rds/ib.h b/net/rds/ib.h
index 148818174a04..96769b86a536 100644
--- a/net/rds/ib.h
+++ b/net/rds/ib.h
@@ -336,7 +336,7 @@ void rds_ib_send_add_credits(struct rds_connection *conn, unsigned int credits);
 void rds_ib_advertise_credits(struct rds_connection *conn, unsigned int posted);
 int rds_ib_send_grab_credits(struct rds_ib_connection *ic, u32 wanted,
                              u32 *adv_credits, int need_posted, int max_posted);
-int rds_ib_xmit_atomic(struct rds_connection *conn, struct rm_atomic_op *op);
+int rds_ib_xmit_atomic(struct rds_connection *conn, struct rds_message *rm);
 
 /* ib_stats.c */
 DECLARE_PER_CPU(struct rds_ib_statistics, rds_ib_stats);
diff --git a/net/rds/ib_send.c b/net/rds/ib_send.c
index d839b403d46b..e6745d827c3a 100644
--- a/net/rds/ib_send.c
+++ b/net/rds/ib_send.c
@@ -225,15 +225,12 @@ void rds_ib_send_cq_comp_handler(struct ib_cq *cq, void *context)
                         /* 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:
                         case IB_WR_ATOMIC_FETCH_AND_ADD:
                         case IB_WR_ATOMIC_CMP_AND_SWP:
-                                /* Nothing to be done - the SG list will be unmapped
-                                 * when the SEND completes. */
+                                if (send->s_rm)
+                                        rds_ib_send_unmap_rm(ic, send, wc.status);
                                 break;
                         default:
                                 if (printk_ratelimit())
@@ -425,6 +422,21 @@ void rds_ib_advertise_credits(struct rds_connection *conn, unsigned int posted)
                 set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
 }
 
+static inline void 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;
+        }
+}
+
 /*
  * 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
@@ -517,7 +529,6 @@ int rds_ib_xmit(struct rds_connection *conn, struct rds_message *rm,
                         rm->data.m_count = 0;
                 }
 
-                ic->i_unsignaled_wrs = rds_ib_sysctl_max_unsig_wrs;
                 rds_message_addref(rm);
                 ic->i_rm = rm;
 
@@ -608,15 +619,7 @@ int rds_ib_xmit(struct rds_connection *conn, struct rds_message *rm,
                         }
                 }
 
-                /*
-                 * 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;
-                }
+                rds_ib_set_wr_signal_state(ic, send, 0);
 
                 /*
                  * Always signal the last one if we're stopping due to flow control.
@@ -656,7 +659,7 @@ int rds_ib_xmit(struct rds_connection *conn, struct rds_message *rm,
         /* if we finished the message then send completion owns it */
         if (scat == &rm->data.m_sg[rm->data.m_count]) {
                 prev->s_rm = ic->i_rm;
-                prev->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED;
+                prev->s_wr.send_flags |= IB_SEND_SOLICITED;
                 ic->i_rm = NULL;
         }
 
@@ -698,9 +701,10 @@ out:
  * 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)
+int rds_ib_xmit_atomic(struct rds_connection *conn, struct rds_message *rm)
 {
         struct rds_ib_connection *ic = conn->c_transport_data;
+        struct rm_atomic_op *op = &rm->atomic;
         struct rds_ib_send_work *send = NULL;
         struct ib_send_wr *failed_wr;
         struct rds_ib_device *rds_ibdev;
@@ -731,12 +735,20 @@ int rds_ib_xmit_atomic(struct rds_connection *conn, struct rm_atomic_op *op)
                 send->s_wr.wr.atomic.compare_add = op->op_swap_add;
                 send->s_wr.wr.atomic.swap = 0;
         }
-        send->s_wr.send_flags = IB_SEND_SIGNALED;
+        rds_ib_set_wr_signal_state(ic, send, op->op_notify);
         send->s_wr.num_sge = 1;
         send->s_wr.next = NULL;
         send->s_wr.wr.atomic.remote_addr = op->op_remote_addr;
         send->s_wr.wr.atomic.rkey = op->op_rkey;
 
+        /*
+         * If there is no data or rdma ops in the message, then
+         * we must fill in s_rm ourselves, so we properly clean up
+         * on completion.
+         */
+        if (!rm->rdma.m_rdma_op.r_active && !rm->data.op_active)
+                send->s_rm = rm;
+
         /* 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);
@@ -836,14 +848,8 @@ int rds_ib_xmit_rdma(struct rds_connection *conn, struct rds_rdma_op *op)
         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;
-                }
+
+                rds_ib_set_wr_signal_state(ic, send, op->r_notify);
 
                 send->s_wr.opcode = op->r_write ? IB_WR_RDMA_WRITE : IB_WR_RDMA_READ;
                 send->s_wr.wr.rdma.remote_addr = remote_addr;
@@ -884,10 +890,6 @@ int rds_ib_xmit_rdma(struct rds_connection *conn, struct rds_rdma_op *op)
                         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;
diff --git a/net/rds/message.c b/net/rds/message.c
index 3ea05c864cd4..a27e493a63a2 100644
--- a/net/rds/message.c
+++ b/net/rds/message.c
@@ -325,6 +325,8 @@ int rds_message_copy_from_user(struct rds_message *rm, struct iovec *first_iov,
                         sg++;
         }
 
+        rm->data.op_active = 1;
+
 out:
         return ret;
 }
diff --git a/net/rds/rds.h b/net/rds/rds.h
index 0c610a102c20..bf2349da4db7 100644
--- a/net/rds/rds.h
+++ b/net/rds/rds.h
@@ -341,6 +341,7 @@ struct rds_message {
                         struct rds_mr           *m_rdma_mr;
                 } rdma;
                 struct rm_data_op {
+                        unsigned int            op_active:1;
                         unsigned int            m_nents;
                         unsigned int            m_count;
                         struct scatterlist      *m_sg;
@@ -418,7 +419,7 @@ struct rds_transport {
         int (*xmit_cong_map)(struct rds_connection *conn,
                              struct rds_cong_map *map, unsigned long offset);
         int (*xmit_rdma)(struct rds_connection *conn, struct rds_rdma_op *op);
-        int (*xmit_atomic)(struct rds_connection *conn, struct rm_atomic_op *op);
+        int (*xmit_atomic)(struct rds_connection *conn, struct rds_message *rm);
         int (*recv)(struct rds_connection *conn);
         int (*inc_copy_to_user)(struct rds_incoming *inc, struct iovec *iov,
                                 size_t size);
diff --git a/net/rds/send.c b/net/rds/send.c
index 5bc35d2f40ea..42fb934293be 100644
--- a/net/rds/send.c
+++ b/net/rds/send.c
@@ -266,7 +266,7 @@ int rds_send_xmit(struct rds_connection *conn)
 
 
                 if (rm->atomic.op_active && !conn->c_xmit_atomic_sent) {
-                        ret = conn->c_trans->xmit_atomic(conn, &rm->atomic);
+                        ret = conn->c_trans->xmit_atomic(conn, rm);
                         if (ret)
                                 break;
                         conn->c_xmit_atomic_sent = 1;
@@ -285,13 +285,18 @@ int rds_send_xmit(struct rds_connection *conn)
                         if (ret)
                                 break;
                         conn->c_xmit_rdma_sent = 1;
+
+                        /* rdmas need data sent, even if just the header */
+                        rm->data.op_active = 1;
+
                         /* The transport owns the mapped memory for now.
                          * You can't unmap it while it's on the send queue */
                         set_bit(RDS_MSG_MAPPED, &rm->m_flags);
                 }
 
-                if (conn->c_xmit_hdr_off < sizeof(struct rds_header) ||
-                    conn->c_xmit_sg < rm->data.m_nents) {
+                if (rm->data.op_active
+                    && (conn->c_xmit_hdr_off < sizeof(struct rds_header) ||
+                        conn->c_xmit_sg < rm->data.m_nents)) {
                         ret = conn->c_trans->xmit(conn, rm,
                                                   conn->c_xmit_hdr_off,
                                                   conn->c_xmit_sg,