RDS: Implement atomic operations

Implement a CMSG-based interface to do FADD and CSWP ops.

Alter send routines to handle atomic ops.

Add atomic counters to stats.

Add xmit_atomic() to struct rds_transport

Inline rds_ib_send_unmap_rdma into unmap_rm

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

8 files changed, 302 insertions, 23 deletions

diff --git a/net/rds/ib.c b/net/rds/ib.c
index 8f2d6dd7700a..f0d29656baff 100644
--- a/net/rds/ib.c
+++ b/net/rds/ib.c
@@ -264,6 +264,7 @@ struct rds_transport rds_ib_transport = {
         .xmit                   = rds_ib_xmit,
         .xmit_cong_map          = NULL,
         .xmit_rdma              = rds_ib_xmit_rdma,
+        .xmit_atomic            = rds_ib_xmit_atomic,
         .recv                   = rds_ib_recv,
         .conn_alloc             = rds_ib_conn_alloc,
         .conn_free              = rds_ib_conn_free,
diff --git a/net/rds/ib.h b/net/rds/ib.h
index 64df4e79b29f..d2fd0aa4fde7 100644
--- a/net/rds/ib.h
+++ b/net/rds/ib.h
@@ -336,6 +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);
 
 /* ib_stats.c */
 DECLARE_PER_CPU(struct rds_ib_statistics, rds_ib_stats);
diff --git a/net/rds/ib_rdma.c b/net/rds/ib_rdma.c
index 0f3b5a2f3fe0..242231f09464 100644
--- a/net/rds/ib_rdma.c
+++ b/net/rds/ib_rdma.c
@@ -298,7 +298,9 @@ static struct rds_ib_mr *rds_ib_alloc_fmr(struct rds_ib_device *rds_ibdev)
         ibmr->fmr = ib_alloc_fmr(rds_ibdev->pd,
                         (IB_ACCESS_LOCAL_WRITE |
                          IB_ACCESS_REMOTE_READ |
-                         IB_ACCESS_REMOTE_WRITE),
+                         IB_ACCESS_REMOTE_WRITE|
+                         IB_ACCESS_REMOTE_ATOMIC),
+
                         &pool->fmr_attr);
         if (IS_ERR(ibmr->fmr)) {
                 err = PTR_ERR(ibmr->fmr);
diff --git a/net/rds/ib_send.c b/net/rds/ib_send.c
index f0edfdb2866c..b2bd164434ad 100644
--- a/net/rds/ib_send.c
+++ b/net/rds/ib_send.c
@@ -62,15 +62,17 @@ static void rds_ib_send_rdma_complete(struct rds_message *rm,
         rds_rdma_send_complete(rm, notify_status);
 }
 
-static void rds_ib_send_unmap_rdma(struct rds_ib_connection *ic,
-                                   struct rds_rdma_op *op)
+static void rds_ib_send_atomic_complete(struct rds_message *rm,
+                                      int wc_status)
 {
-        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;
-        }
+        int notify_status;
+
+        if (wc_status != IB_WC_SUCCESS)
+                notify_status = RDS_RDMA_OTHER_ERROR;
+        else
+                notify_status = RDS_RDMA_SUCCESS;
+
+        rds_atomic_send_complete(rm, notify_status);
 }
 
 static void rds_ib_send_unmap_rm(struct rds_ib_connection *ic,
@@ -86,7 +88,14 @@ static void rds_ib_send_unmap_rm(struct rds_ib_connection *ic,
                         DMA_TO_DEVICE);
 
         if (rm->rdma.m_rdma_op.r_active) {
-                rds_ib_send_unmap_rdma(ic, &rm->rdma.m_rdma_op);
+                struct rds_rdma_op *op = &rm->rdma.m_rdma_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;
+                }
 
                 /* If the user asked for a completion notification on this
                  * message, we can implement three different semantics:
@@ -116,6 +125,24 @@ static void rds_ib_send_unmap_rm(struct rds_ib_connection *ic,
                         rds_stats_add(s_recv_rdma_bytes, rm->rdma.m_rdma_op.r_bytes);
         }
 
+        if (rm->atomic.op_active) {
+                struct rm_atomic_op *op = &rm->atomic;
+
+                /* 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_atomic_complete(rm, wc_status);
+
+                if (rm->atomic.op_type == RDS_ATOMIC_TYPE_CSWP)
+                        rds_stats_inc(s_atomic_cswp);
+                else
+                        rds_stats_inc(s_atomic_fadd);
+        }
+
         /* If anyone waited for this message to get flushed out, wake
          * them up now */
         rds_message_unmapped(rm);
@@ -158,12 +185,9 @@ void rds_ib_send_clear_ring(struct rds_ib_connection *ic)
         u32 i;
 
         for (i = 0, send = ic->i_sends; i < ic->i_send_ring.w_nr; i++, send++) {
-                if (send->s_wr.opcode == 0xdead)
+                if (!send->s_rm || 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);
+                rds_ib_send_unmap_rm(ic, send, IB_WC_WR_FLUSH_ERR);
         }
 }
 
@@ -218,6 +242,8 @@ void rds_ib_send_cq_comp_handler(struct ib_cq *cq, void *context)
                                 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. */
                                 break;
@@ -243,8 +269,7 @@ void rds_ib_send_cq_comp_handler(struct ib_cq *cq, void *context)
 
                                 rm = rds_send_get_message(conn, send->s_op);
                                 if (rm) {
-                                        if (rm->rdma.m_rdma_op.r_active)
-                                                rds_ib_send_unmap_rdma(ic, &rm->rdma.m_rdma_op);
+                                        rds_ib_send_unmap_rm(ic, send, wc.status);
                                         rds_ib_send_rdma_complete(rm, wc.status);
                                         rds_message_put(rm);
                                 }
@@ -736,6 +761,89 @@ out:
         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;
+        struct ib_send_wr *failed_wr;
+        struct rds_ib_device *rds_ibdev;
+        u32 pos;
+        u32 work_alloc;
+        int ret;
+
+        rds_ibdev = ib_get_client_data(ic->i_cm_id->device, &rds_ib_client);
+
+        work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, 1, &pos);
+        if (work_alloc != 1) {
+                rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
+                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_wr.opcode = IB_WR_ATOMIC_CMP_AND_SWP;
+                send->s_wr.wr.atomic.compare_add = op->op_compare;
+                send->s_wr.wr.atomic.swap = op->op_swap_add;
+        } else { /* FADD */
+                send->s_wr.opcode = IB_WR_ATOMIC_FETCH_AND_ADD;
+                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;
+        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;
+
+        /* 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 = ib_sg_dma_address(ic->i_cm_id->device, op->op_sg);
+        send->s_sge[0].length = ib_sg_dma_len(ic->i_cm_id->device, op->op_sg);
+        send->s_sge[0].lkey = ic->i_mr->lkey;
+
+        rdsdebug("rva %Lx rpa %Lx len %u\n", op->op_remote_addr,
+                 send->s_sge[0].addr, send->s_sge[0].length);
+
+        failed_wr = &send->s_wr;
+        ret = ib_post_send(ic->i_cm_id->qp, &send->s_wr, &failed_wr);
+        rdsdebug("ic %p send %p (wr %p) ret %d wr %p\n", ic,
+                 send, &send->s_wr, ret, failed_wr);
+        BUG_ON(failed_wr != &send->s_wr);
+        if (ret) {
+                printk(KERN_WARNING "RDS/IB: atomic 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 != &send->s_wr)) {
+                printk(KERN_WARNING "RDS/IB: atomic ib_post_send() rc=%d, but failed_wqe updated!\n", ret);
+                BUG_ON(failed_wr != &send->s_wr);
+        }
+
+out:
+        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;
diff --git a/net/rds/rdma.c b/net/rds/rdma.c
index 4fda33045598..a7019df38c70 100644
--- a/net/rds/rdma.c
+++ b/net/rds/rdma.c
@@ -719,3 +719,76 @@ int rds_cmsg_rdma_map(struct rds_sock *rs, struct rds_message *rm,
 
         return __rds_rdma_map(rs, CMSG_DATA(cmsg), &rm->m_rdma_cookie, &rm->rdma.m_rdma_mr);
 }
+
+/*
+ * Fill in rds_message for an atomic request.
+ */
+int rds_cmsg_atomic(struct rds_sock *rs, struct rds_message *rm,
+                    struct cmsghdr *cmsg)
+{
+        struct page *page = NULL;
+        struct rds_atomic_args *args;
+        int ret = 0;
+
+        if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct rds_atomic_args))
+         || rm->atomic.op_active)
+                return -EINVAL;
+
+        args = CMSG_DATA(cmsg);
+
+        if (cmsg->cmsg_type == RDS_CMSG_ATOMIC_CSWP) {
+                rm->atomic.op_type = RDS_ATOMIC_TYPE_CSWP;
+                rm->atomic.op_swap_add = args->cswp.swap;
+                rm->atomic.op_compare = args->cswp.compare;
+        } else {
+                rm->atomic.op_type = RDS_ATOMIC_TYPE_FADD;
+                rm->atomic.op_swap_add = args->fadd.add;
+        }
+
+        rm->m_rdma_cookie = args->cookie;
+        rm->atomic.op_notify = !!(args->flags & RDS_RDMA_NOTIFY_ME);
+        rm->atomic.op_recverr = rs->rs_recverr;
+        rm->atomic.op_sg = rds_message_alloc_sgs(rm, 1);
+
+        /* verify 8 byte-aligned */
+        if (args->local_addr & 0x7) {
+                ret = -EFAULT;
+                goto err;
+        }
+
+        ret = rds_pin_pages(args->local_addr, 1, &page, 1);
+        if (ret != 1)
+                goto err;
+        ret = 0;
+
+        sg_set_page(rm->atomic.op_sg, page, 8, offset_in_page(args->local_addr));
+
+        if (rm->atomic.op_notify || rm->atomic.op_recverr) {
+                /* We allocate an uninitialized notifier here, because
+                 * we don't want to do that in the completion handler. We
+                 * would have to use GFP_ATOMIC there, and don't want to deal
+                 * with failed allocations.
+                 */
+                rm->atomic.op_notifier = kmalloc(sizeof(*rm->atomic.op_notifier), GFP_KERNEL);
+                if (!rm->atomic.op_notifier) {
+                        ret = -ENOMEM;
+                        goto err;
+                }
+
+                rm->atomic.op_notifier->n_user_token = args->user_token;
+                rm->atomic.op_notifier->n_status = RDS_RDMA_SUCCESS;
+        }
+
+        rm->atomic.op_rkey = rds_rdma_cookie_key(rm->m_rdma_cookie);
+        rm->atomic.op_remote_addr = args->remote_addr + rds_rdma_cookie_offset(args->cookie);
+
+        rm->atomic.op_active = 1;
+
+        return ret;
+err:
+        if (page)
+                put_page(page);
+        kfree(rm->atomic.op_notifier);
+
+        return ret;
+}
diff --git a/net/rds/rds.h b/net/rds/rds.h
index 0bb4957e0cfc..830e2bbb3332 100644
--- a/net/rds/rds.h
+++ b/net/rds/rds.h
@@ -97,6 +97,7 @@ struct rds_connection {
         unsigned int            c_xmit_hdr_off;
         unsigned int            c_xmit_data_off;
         unsigned int            c_xmit_rdma_sent;
+        unsigned int            c_xmit_atomic_sent;
 
         spinlock_t              c_lock;         /* protect msg queues */
         u64                     c_next_tx_seq;
@@ -260,6 +261,10 @@ static inline u32 rds_rdma_cookie_offset(rds_rdma_cookie_t cookie)
         return cookie >> 32;
 }
 
+/* atomic operation types */
+#define RDS_ATOMIC_TYPE_CSWP            0
+#define RDS_ATOMIC_TYPE_FADD            1
+
 /*
  * m_sock_item and m_conn_item are on lists that are serialized under
  * conn->c_lock.  m_sock_item has additional meaning in that once it is empty
@@ -315,11 +320,27 @@ struct rds_message {
         struct rds_sock         *m_rs;
         rds_rdma_cookie_t       m_rdma_cookie;
         struct {
-                struct {
+                struct rm_atomic_op {
+                        int                     op_type;
+                        uint64_t                op_swap_add;
+                        uint64_t                op_compare;
+
+                        u32                     op_rkey;
+                        u64                     op_remote_addr;
+                        unsigned int            op_notify:1;
+                        unsigned int            op_recverr:1;
+                        unsigned int            op_mapped:1;
+                        unsigned int            op_active:1;
+                        struct rds_notifier     *op_notifier;
+                        struct scatterlist      *op_sg;
+
+                        struct rds_mr           *op_rdma_mr;
+                } atomic;
+                struct rm_rdma_op {
                         struct rds_rdma_op      m_rdma_op;
                         struct rds_mr           *m_rdma_mr;
                 } rdma;
-                struct {
+                struct rm_data_op {
                         unsigned int            m_nents;
                         unsigned int            m_count;
                         struct scatterlist      *m_sg;
@@ -397,6 +418,7 @@ 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 (*recv)(struct rds_connection *conn);
         int (*inc_copy_to_user)(struct rds_incoming *inc, struct iovec *iov,
                                 size_t size);
@@ -546,6 +568,8 @@ struct rds_statistics {
         uint64_t        s_cong_update_received;
         uint64_t        s_cong_send_error;
         uint64_t        s_cong_send_blocked;
+        uint64_t        s_atomic_cswp;
+        uint64_t        s_atomic_fadd;
 };
 
 /* af_rds.c */
@@ -722,7 +746,10 @@ int rds_cmsg_rdma_args(struct rds_sock *rs, struct rds_message *rm,
 int rds_cmsg_rdma_map(struct rds_sock *rs, struct rds_message *rm,
                           struct cmsghdr *cmsg);
 void rds_rdma_free_op(struct rds_rdma_op *ro);
-void rds_rdma_send_complete(struct rds_message *rm, int);
+void rds_rdma_send_complete(struct rds_message *rm, int wc_status);
+void rds_atomic_send_complete(struct rds_message *rm, int wc_status);
+int rds_cmsg_atomic(struct rds_sock *rs, struct rds_message *rm,
+                    struct cmsghdr *cmsg);
 
 extern void __rds_put_mr_final(struct rds_mr *mr);
 static inline void rds_mr_put(struct rds_mr *mr)
diff --git a/net/rds/send.c b/net/rds/send.c
index b751a8e77c41..f3f4e79274bf 100644
--- a/net/rds/send.c
+++ b/net/rds/send.c
@@ -73,6 +73,7 @@ void rds_send_reset(struct rds_connection *conn)
         conn->c_xmit_hdr_off = 0;
         conn->c_xmit_data_off = 0;
         conn->c_xmit_rdma_sent = 0;
+        conn->c_xmit_atomic_sent = 0;
 
         conn->c_map_queued = 0;
 
@@ -171,6 +172,7 @@ int rds_send_xmit(struct rds_connection *conn)
                         conn->c_xmit_hdr_off = 0;
                         conn->c_xmit_data_off = 0;
                         conn->c_xmit_rdma_sent = 0;
+                        conn->c_xmit_atomic_sent = 0;
 
                         /* Release the reference to the previous message. */
                         rds_message_put(rm);
@@ -262,6 +264,17 @@ int rds_send_xmit(struct rds_connection *conn)
                         conn->c_xmit_rm = rm;
                 }
 
+
+                if (rm->atomic.op_active && !conn->c_xmit_atomic_sent) {
+                        ret = conn->c_trans->xmit_atomic(conn, &rm->atomic);
+                        if (ret)
+                                break;
+                        conn->c_xmit_atomic_sent = 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);
+                }
+
                 /*
                  * Try and send an rdma message.  Let's see if we can
                  * keep this simple and require that the transport either
@@ -443,6 +456,41 @@ void rds_rdma_send_complete(struct rds_message *rm, int status)
 EXPORT_SYMBOL_GPL(rds_rdma_send_complete);
 
 /*
+ * Just like above, except looks at atomic op
+ */
+void rds_atomic_send_complete(struct rds_message *rm, int status)
+{
+        struct rds_sock *rs = NULL;
+        struct rm_atomic_op *ao;
+        struct rds_notifier *notifier;
+
+        spin_lock(&rm->m_rs_lock);
+
+        ao = &rm->atomic;
+        if (test_bit(RDS_MSG_ON_SOCK, &rm->m_flags)
+            && ao->op_active && ao->op_notify && ao->op_notifier) {
+                notifier = ao->op_notifier;
+                rs = rm->m_rs;
+                sock_hold(rds_rs_to_sk(rs));
+
+                notifier->n_status = status;
+                spin_lock(&rs->rs_lock);
+                list_add_tail(&notifier->n_list, &rs->rs_notify_queue);
+                spin_unlock(&rs->rs_lock);
+
+                ao->op_notifier = NULL;
+        }
+
+        spin_unlock(&rm->m_rs_lock);
+
+        if (rs) {
+                rds_wake_sk_sleep(rs);
+                sock_put(rds_rs_to_sk(rs));
+        }
+}
+EXPORT_SYMBOL_GPL(rds_atomic_send_complete);
+
+/*
  * This is the same as rds_rdma_send_complete except we
  * don't do any locking - we have all the ingredients (message,
  * socket, socket lock) and can just move the notifier.
@@ -788,6 +836,11 @@ static int rds_rm_size(struct msghdr *msg, int data_len)
                         /* these are valid but do no add any size */
                         break;
 
+                case RDS_CMSG_ATOMIC_CSWP:
+                case RDS_CMSG_ATOMIC_FADD:
+                        size += sizeof(struct scatterlist);
+                        break;
+
                 default:
                         return -EINVAL;
                 }
@@ -813,7 +866,7 @@ static int rds_cmsg_send(struct rds_sock *rs, struct rds_message *rm,
                         continue;
 
                 /* As a side effect, RDMA_DEST and RDMA_MAP will set
-                 * rm->m_rdma_cookie and rm->m_rdma_mr.
+                 * rm->rdma.m_rdma_cookie and rm->rdma.m_rdma_mr.
                  */
                 switch (cmsg->cmsg_type) {
                 case RDS_CMSG_RDMA_ARGS:
@@ -829,6 +882,10 @@ static int rds_cmsg_send(struct rds_sock *rs, struct rds_message *rm,
                         if (!ret)
                                 *allocated_mr = 1;
                         break;
+                case RDS_CMSG_ATOMIC_CSWP:
+                case RDS_CMSG_ATOMIC_FADD:
+                        ret = rds_cmsg_atomic(rs, rm, cmsg);
+                        break;
 
                 default:
                         return -EINVAL;
@@ -926,10 +983,18 @@ int rds_sendmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg,
                 goto out;
 
         if ((rm->m_rdma_cookie || rm->rdma.m_rdma_op.r_active) &&
-            !conn->c_trans->xmit_rdma) {
+               !conn->c_trans->xmit_rdma) {
                 if (printk_ratelimit())
                         printk(KERN_NOTICE "rdma_op %p conn xmit_rdma %p\n",
-                                &rm->rdma.m_rdma_op, conn->c_trans->xmit_rdma);
+                               &rm->rdma.m_rdma_op, conn->c_trans->xmit_rdma);
+                ret = -EOPNOTSUPP;
+                goto out;
+        }
+
+        if (rm->atomic.op_active && !conn->c_trans->xmit_atomic) {
+                if (printk_ratelimit())
+                        printk(KERN_NOTICE "atomic_op %p conn xmit_atomic %p\n",
+                               &rm->atomic, conn->c_trans->xmit_atomic);
                 ret = -EOPNOTSUPP;
                 goto out;
         }
diff --git a/net/rds/stats.c b/net/rds/stats.c
index 7598eb07cfb1..c66d95d9c262 100644
--- a/net/rds/stats.c
+++ b/net/rds/stats.c
@@ -75,6 +75,8 @@ static const char *const rds_stat_names[] = {
         "cong_update_received",
         "cong_send_error",
         "cong_send_blocked",
+        "s_atomic_cswp",
+        "s_atomic_fadd",
 };
 
 void rds_stats_info_copy(struct rds_info_iterator *iter,