RDMA/qedr: SRQ's bug fixes

QP's with the same SRQ, working on different CQs and running in parallel
on different CPUs could lead to a race when maintaining the SRQ consumer
count, and leads to FW running out of SRQs. Update the consumer
atomically.  Make sure the wqe_prod is updated after the sge_prod due to
FW requirements.

Fixes: 3491c9e799fb ("qedr: Add support for kernel mode SRQ's")
Link: https://lore.kernel.org/r/20200708195526.31040-1-ybason@marvell.com
Signed-off-by: Michal Kalderon <mkalderon@marvell.com>
Signed-off-by: Yuval Basson <ybason@marvell.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

diff --git a/drivers/infiniband/hw/qedr/qedr.h b/drivers/infiniband/hw/qedr/qedr.h
index fdf90ec..aa33202 100644 (file)
--- a/drivers/infiniband/hw/qedr/qedr.h
+++ b/drivers/infiniband/hw/qedr/qedr.h
@@ -344,10 +344,10 @@ struct qedr_srq_hwq_info {
        u32 wqe_prod;
        u32 sge_prod;
        u32 wr_prod_cnt;
-       u32 wr_cons_cnt;
+       atomic_t wr_cons_cnt;
        u32 num_elems;
 
-       u32 *virt_prod_pair_addr;
+       struct rdma_srq_producers *virt_prod_pair_addr;
        dma_addr_t phy_prod_pair_addr;
 };
 

diff --git a/drivers/infiniband/hw/qedr/verbs.c b/drivers/infiniband/hw/qedr/verbs.c
index 3d7d561..42273aa 100644 (file)
--- a/drivers/infiniband/hw/qedr/verbs.c
+++ b/drivers/infiniband/hw/qedr/verbs.c
@@ -3686,7 +3686,7 @@ static u32 qedr_srq_elem_left(struct qedr_srq_hwq_info *hw_srq)
         * count and consumer count and subtract it from max
         * work request supported so that we get elements left.
         */
-       used = hw_srq->wr_prod_cnt - hw_srq->wr_cons_cnt;
+       used = hw_srq->wr_prod_cnt - (u32)atomic_read(&hw_srq->wr_cons_cnt);
 
        return hw_srq->max_wr - used;
 }
@@ -3701,7 +3701,6 @@ int qedr_post_srq_recv(struct ib_srq *ibsrq, const struct ib_recv_wr *wr,
        unsigned long flags;
        int status = 0;
        u32 num_sge;
-       u32 offset;
 
        spin_lock_irqsave(&srq->lock, flags);
 
@@ -3714,7 +3713,8 @@ int qedr_post_srq_recv(struct ib_srq *ibsrq, const struct ib_recv_wr *wr,
                if (!qedr_srq_elem_left(hw_srq) ||
                    wr->num_sge > srq->hw_srq.max_sges) {
                        DP_ERR(dev, "Can't post WR  (%d,%d) || (%d > %d)\n",
-                              hw_srq->wr_prod_cnt, hw_srq->wr_cons_cnt,
+                              hw_srq->wr_prod_cnt,
+                              atomic_read(&hw_srq->wr_cons_cnt),
                               wr->num_sge, srq->hw_srq.max_sges);
                        status = -ENOMEM;
                        *bad_wr = wr;
@@ -3748,22 +3748,20 @@ int qedr_post_srq_recv(struct ib_srq *ibsrq, const struct ib_recv_wr *wr,
                        hw_srq->sge_prod++;
                }
 
-               /* Flush WQE and SGE information before
+               /* Update WQE and SGE information before
                 * updating producer.
                 */
-               wmb();
+               dma_wmb();
 
                /* SRQ producer is 8 bytes. Need to update SGE producer index
                 * in first 4 bytes and need to update WQE producer in
                 * next 4 bytes.
                 */
-               *srq->hw_srq.virt_prod_pair_addr = hw_srq->sge_prod;
-               offset = offsetof(struct rdma_srq_producers, wqe_prod);
-               *((u8 *)srq->hw_srq.virt_prod_pair_addr + offset) =
-                       hw_srq->wqe_prod;
+               srq->hw_srq.virt_prod_pair_addr->sge_prod = hw_srq->sge_prod;
+               /* Make sure sge producer is updated first */
+               dma_wmb();
+               srq->hw_srq.virt_prod_pair_addr->wqe_prod = hw_srq->wqe_prod;
 
-               /* Flush producer after updating it. */
-               wmb();
                wr = wr->next;
        }
 
@@ -4182,7 +4180,7 @@ static int process_resp_one_srq(struct qedr_dev *dev, struct qedr_qp *qp,
        } else {
                __process_resp_one(dev, qp, cq, wc, resp, wr_id);
        }
-       srq->hw_srq.wr_cons_cnt++;
+       atomic_inc(&srq->hw_srq.wr_cons_cnt);
 
        return 1;
 }