iser-target: avoid posting a recv buffer twice

We pre-allocate our send-queues and might overflow them
in case we have multi work-request operations which tend
to occur for large RDMA transfers over devices with limited
allowed sg elements. When we get to a queue-full condition
we might retry again later, so track our receive buffers
so we don't repost them for a retry case.

Reported-by: Potnuri Bharat Teja <bharat@chelsio.com>
Tested-by: Potnuri Bharat Teja <bharat@chelsio.com>
Reviewed-by: Potnuri Bharat Teja <bharat@chelsio.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

diff --git a/drivers/infiniband/ulp/isert/ib_isert.c b/drivers/infiniband/ulp/isert/ib_isert.c
index 9b33c0c..fcbed35 100644 (file)
--- a/drivers/infiniband/ulp/isert/ib_isert.c
+++ b/drivers/infiniband/ulp/isert/ib_isert.c
@@ -817,6 +817,7 @@ isert_post_recvm(struct isert_conn *isert_conn, u32 count)
                rx_wr->sg_list = &rx_desc->rx_sg;
                rx_wr->num_sge = 1;
                rx_wr->next = rx_wr + 1;
+               rx_desc->in_use = false;
        }
        rx_wr--;
        rx_wr->next = NULL; /* mark end of work requests list */
@@ -835,6 +836,15 @@ isert_post_recv(struct isert_conn *isert_conn, struct iser_rx_desc *rx_desc)
        struct ib_recv_wr *rx_wr_failed, rx_wr;
        int ret;
 
+       if (!rx_desc->in_use) {
+               /*
+                * if the descriptor is not in-use we already reposted it
+                * for recv, so just silently return
+                */
+               return 0;
+       }
+
+       rx_desc->in_use = false;
        rx_wr.wr_cqe = &rx_desc->rx_cqe;
        rx_wr.sg_list = &rx_desc->rx_sg;
        rx_wr.num_sge = 1;
@@ -1397,6 +1407,8 @@ isert_recv_done(struct ib_cq *cq, struct ib_wc *wc)
                return;
        }
 
+       rx_desc->in_use = true;
+
        ib_dma_sync_single_for_cpu(ib_dev, rx_desc->dma_addr,
                        ISER_RX_PAYLOAD_SIZE, DMA_FROM_DEVICE);
 

diff --git a/drivers/infiniband/ulp/isert/ib_isert.h b/drivers/infiniband/ulp/isert/ib_isert.h
index c02ada5..87d994d 100644 (file)
--- a/drivers/infiniband/ulp/isert/ib_isert.h
+++ b/drivers/infiniband/ulp/isert/ib_isert.h
@@ -60,7 +60,7 @@
 
 #define ISER_RX_PAD_SIZE       (ISCSI_DEF_MAX_RECV_SEG_LEN + 4096 - \
                (ISER_RX_PAYLOAD_SIZE + sizeof(u64) + sizeof(struct ib_sge) + \
-                sizeof(struct ib_cqe)))
+                sizeof(struct ib_cqe) + sizeof(bool)))
 
 #define ISCSI_ISER_SG_TABLESIZE                256
 
@@ -85,6 +85,7 @@ struct iser_rx_desc {
        u64             dma_addr;
        struct ib_sge   rx_sg;
        struct ib_cqe   rx_cqe;
+       bool            in_use;
        char            pad[ISER_RX_PAD_SIZE];
 } __packed;