IB/iser: Use beacon to indicate all completions were consumed

Avoid post_send counting (atomic) in the IO path just to keep track of
how many completions we need to consume.  Use a beacon post to indicate
that all prior posts completed.

Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

diff --git a/drivers/infiniband/ulp/iser/iscsi_iser.h b/drivers/infiniband/ulp/iser/iscsi_iser.h
index 1617c5c..4fcb256 100644 (file)
--- a/drivers/infiniband/ulp/iser/iscsi_iser.h
+++ b/drivers/infiniband/ulp/iser/iscsi_iser.h
@@ -150,6 +150,7 @@
 #define ISER_RSV                       0x04
 
 #define ISER_FASTREG_LI_WRID           0xffffffffffffffffULL
+#define ISER_BEACON_WRID               0xfffffffffffffffeULL
 
 struct iser_hdr {
        u8      flags;
@@ -335,11 +336,11 @@ struct fast_reg_descriptor {
  * @cma_id:              rdma_cm connection maneger handle
  * @qp:                  Connection Queue-pair
  * @post_recv_buf_count: post receive counter
- * @post_send_buf_count: post send counter
  * @rx_wr:               receive work request for batch posts
  * @device:              reference to iser device
  * @comp:                iser completion context
  * @pi_support:          Indicate device T10-PI support
+ * @beacon:              beacon send wr to signal all flush errors were drained
  * @flush_comp:          completes when all connection completions consumed
  * @lock:                protects fmr/fastreg pool
  * @union.fmr:
@@ -355,11 +356,11 @@ struct ib_conn {
        struct rdma_cm_id           *cma_id;
        struct ib_qp                *qp;
        int                          post_recv_buf_count;
-       atomic_t                     post_send_buf_count;
        struct ib_recv_wr            rx_wr[ISER_MIN_POSTED_RX];
        struct iser_device          *device;
        struct iser_comp            *comp;
        bool                         pi_support;
+       struct ib_send_wr            beacon;
        struct completion            flush_comp;
        spinlock_t                   lock;
        union {

diff --git a/drivers/infiniband/ulp/iser/iser_initiator.c b/drivers/infiniband/ulp/iser/iser_initiator.c
index 359c0b8..ffbdf92 100644 (file)
--- a/drivers/infiniband/ulp/iser/iser_initiator.c
+++ b/drivers/infiniband/ulp/iser/iser_initiator.c
@@ -350,12 +350,10 @@ static int iser_post_rx_bufs(struct iscsi_conn *conn, struct iscsi_hdr *req)
                return 0;
 
        /*
-        * Check that there is one posted recv buffer (for the last login
-        * response) and no posted send buffers left - they must have been
-        * consumed during previous login phases.
+        * Check that there is one posted recv buffer
+        * (for the last login response).
         */
        WARN_ON(ib_conn->post_recv_buf_count != 1);
-       WARN_ON(atomic_read(&ib_conn->post_send_buf_count) != 0);
 
        if (session->discovery_sess) {
                iser_info("Discovery session, re-using login RX buffer\n");
@@ -634,8 +632,6 @@ void iser_snd_completion(struct iser_tx_desc *tx_desc,
                tx_desc = NULL;
        }
 
-       atomic_dec(&ib_conn->post_send_buf_count);
-
        if (tx_desc && tx_desc->type == ISCSI_TX_CONTROL) {
                /* this arithmetic is legal by libiscsi dd_data allocation */
                task = (void *) ((long)(void *)tx_desc -

diff --git a/drivers/infiniband/ulp/iser/iser_verbs.c b/drivers/infiniband/ulp/iser/iser_verbs.c
index eedc27a..805a9bd 100644 (file)
--- a/drivers/infiniband/ulp/iser/iser_verbs.c
+++ b/drivers/infiniband/ulp/iser/iser_verbs.c
@@ -41,7 +41,8 @@
 #define ISCSI_ISER_MAX_CONN    8
 #define ISER_MAX_RX_LEN                (ISER_QP_MAX_RECV_DTOS * ISCSI_ISER_MAX_CONN)
 #define ISER_MAX_TX_LEN                (ISER_QP_MAX_REQ_DTOS  * ISCSI_ISER_MAX_CONN)
-#define ISER_MAX_CQ_LEN                (ISER_MAX_RX_LEN + ISER_MAX_TX_LEN)
+#define ISER_MAX_CQ_LEN                (ISER_MAX_RX_LEN + ISER_MAX_TX_LEN + \
+                                ISCSI_ISER_MAX_CONN)
 
 static int iser_cq_poll_limit = 512;
 
@@ -457,10 +458,10 @@ static int iser_create_ib_conn_res(struct ib_conn *ib_conn)
        init_attr.sq_sig_type   = IB_SIGNAL_REQ_WR;
        init_attr.qp_type       = IB_QPT_RC;
        if (ib_conn->pi_support) {
-               init_attr.cap.max_send_wr = ISER_QP_SIG_MAX_REQ_DTOS;
+               init_attr.cap.max_send_wr = ISER_QP_SIG_MAX_REQ_DTOS + 1;
                init_attr.create_flags |= IB_QP_CREATE_SIGNATURE_EN;
        } else {
-               init_attr.cap.max_send_wr  = ISER_QP_MAX_REQ_DTOS;
+               init_attr.cap.max_send_wr  = ISER_QP_MAX_REQ_DTOS + 1;
        }
 
        ret = rdma_create_qp(ib_conn->cma_id, device->pd, &init_attr);
@@ -634,6 +635,7 @@ void iser_conn_release(struct iser_conn *iser_conn)
 int iser_conn_terminate(struct iser_conn *iser_conn)
 {
        struct ib_conn *ib_conn = &iser_conn->ib_conn;
+       struct ib_send_wr *bad_wr;
        int err = 0;
 
        /* terminate the iser conn only if the conn state is UP */
@@ -658,6 +660,11 @@ int iser_conn_terminate(struct iser_conn *iser_conn)
                        iser_err("Failed to disconnect, conn: 0x%p err %d\n",
                                 iser_conn, err);
 
+               /* post an indication that all flush errors were consumed */
+               err = ib_post_send(ib_conn->qp, &ib_conn->beacon, &bad_wr);
+               if (err)
+                       iser_err("conn %p failed to post beacon", ib_conn);
+
                wait_for_completion(&ib_conn->flush_comp);
        }
 
@@ -867,7 +874,6 @@ void iser_conn_init(struct iser_conn *iser_conn)
 {
        iser_conn->state = ISER_CONN_INIT;
        iser_conn->ib_conn.post_recv_buf_count = 0;
-       atomic_set(&iser_conn->ib_conn.post_send_buf_count, 0);
        init_completion(&iser_conn->ib_conn.flush_comp);
        init_completion(&iser_conn->stop_completion);
        init_completion(&iser_conn->ib_completion);
@@ -900,6 +906,9 @@ int iser_connect(struct iser_conn   *iser_conn,
 
        iser_conn->state = ISER_CONN_PENDING;
 
+       ib_conn->beacon.wr_id = ISER_BEACON_WRID;
+       ib_conn->beacon.opcode = IB_WR_SEND;
+
        ib_conn->cma_id = rdma_create_id(iser_cma_handler,
                                         (void *)iser_conn,
                                         RDMA_PS_TCP, IB_QPT_RC);
@@ -1106,13 +1115,10 @@ int iser_post_send(struct ib_conn *ib_conn, struct iser_tx_desc *tx_desc)
        send_wr.opcode     = IB_WR_SEND;
        send_wr.send_flags = IB_SEND_SIGNALED;
 
-       atomic_inc(&ib_conn->post_send_buf_count);
-
        ib_ret = ib_post_send(ib_conn->qp, &send_wr, &send_wr_failed);
-       if (ib_ret) {
+       if (ib_ret)
                iser_err("ib_post_send failed, ret:%d\n", ib_ret);
-               atomic_dec(&ib_conn->post_send_buf_count);
-       }
+
        return ib_ret;
 }
 
@@ -1164,7 +1170,6 @@ iser_handle_comp_error(struct ib_conn *ib_conn,
        if (is_iser_tx_desc(iser_conn, (void *)wc->wr_id)) {
                struct iser_tx_desc *desc = (struct iser_tx_desc *)wc->wr_id;
 
-               atomic_dec(&ib_conn->post_send_buf_count);
                if (desc->type == ISCSI_TX_DATAOUT)
                        kmem_cache_free(ig.desc_cache, desc);
        } else {
@@ -1196,7 +1201,6 @@ static void iser_handle_wc(struct ib_wc *wc)
                if (wc->opcode == IB_WC_SEND) {
                        tx_desc = (struct iser_tx_desc *)wc->wr_id;
                        iser_snd_completion(tx_desc, ib_conn);
-                       atomic_dec(&ib_conn->post_send_buf_count);
                } else {
                        iser_err("Unknown wc opcode %d\n", wc->opcode);
                }
@@ -1207,12 +1211,12 @@ static void iser_handle_wc(struct ib_wc *wc)
                else
                        iser_dbg("flush error: wr id %llx\n", wc->wr_id);
 
-               if (wc->wr_id != ISER_FASTREG_LI_WRID)
+               if (wc->wr_id != ISER_FASTREG_LI_WRID &&
+                   wc->wr_id != ISER_BEACON_WRID)
                        iser_handle_comp_error(ib_conn, wc);
 
                /* complete in case all flush errors were consumed */
-               if (ib_conn->post_recv_buf_count == 0 &&
-                   atomic_read(&ib_conn->post_send_buf_count) == 0)
+               if (wc->wr_id == ISER_BEACON_WRID)
                        complete(&ib_conn->flush_comp);
        }
 }