From: Michael S. Tsirkin <[EMAIL PROTECTED]> Locking during the poll cq operation can be reduced by locking the cq while qp is being removed from the qp array. This also avoids an extra atomic operation for reference counting.
Signed-off-by: Michael S. Tsirkin <[EMAIL PROTECTED]> Signed-off-by: Roland Dreier <[EMAIL PROTECTED]> --- linux-export.orig/drivers/infiniband/hw/mthca/mthca_cq.c 2005-03-03 14:12:52.368554099 -0800 +++ linux-export/drivers/infiniband/hw/mthca/mthca_cq.c 2005-03-03 14:12:52.923433653 -0800 @@ -418,14 +418,14 @@ spin_unlock(&(*cur_qp)->lock); } - spin_lock(&dev->qp_table.lock); + /* + * We do not have to take the QP table lock here, + * because CQs will be locked while QPs are removed + * from the table. + */ *cur_qp = mthca_array_get(&dev->qp_table.qp, be32_to_cpu(cqe->my_qpn) & (dev->limits.num_qps - 1)); - if (*cur_qp) - atomic_inc(&(*cur_qp)->refcount); - spin_unlock(&dev->qp_table.lock); - if (!*cur_qp) { mthca_warn(dev, "CQ entry for unknown QP %06x\n", be32_to_cpu(cqe->my_qpn) & 0xffffff); @@ -537,12 +537,8 @@ inc_cons_index(dev, cq, freed); } - if (qp) { + if (qp) spin_unlock(&qp->lock); - if (atomic_dec_and_test(&qp->refcount)) - wake_up(&qp->wait); - } - spin_unlock_irqrestore(&cq->lock, flags); --- linux-export.orig/drivers/infiniband/hw/mthca/mthca_qp.c 2005-02-03 16:59:28.000000000 -0800 +++ linux-export/drivers/infiniband/hw/mthca/mthca_qp.c 2005-03-03 14:12:52.924433436 -0800 @@ -1083,9 +1083,21 @@ return 0; err_out_free: - spin_lock_irq(&dev->qp_table.lock); + /* + * Lock CQs here, so that CQ polling code can do QP lookup + * without taking a lock. + */ + spin_lock_irq(&send_cq->lock); + if (send_cq != recv_cq) + spin_lock(&recv_cq->lock); + + spin_lock(&dev->qp_table.lock); mthca_array_clear(&dev->qp_table.qp, mqpn); - spin_unlock_irq(&dev->qp_table.lock); + spin_unlock(&dev->qp_table.lock); + + if (send_cq != recv_cq) + spin_unlock(&recv_cq->lock); + spin_unlock_irq(&send_cq->lock); err_out: dma_free_coherent(&dev->pdev->dev, sqp->header_buf_size, @@ -1100,11 +1112,28 @@ u8 status; int size; int i; + struct mthca_cq *send_cq; + struct mthca_cq *recv_cq; + + send_cq = to_mcq(qp->ibqp.send_cq); + recv_cq = to_mcq(qp->ibqp.recv_cq); - spin_lock_irq(&dev->qp_table.lock); + /* + * Lock CQs here, so that CQ polling code can do QP lookup + * without taking a lock. + */ + spin_lock_irq(&send_cq->lock); + if (send_cq != recv_cq) + spin_lock(&recv_cq->lock); + + spin_lock(&dev->qp_table.lock); mthca_array_clear(&dev->qp_table.qp, qp->qpn & (dev->limits.num_qps - 1)); - spin_unlock_irq(&dev->qp_table.lock); + spin_unlock(&dev->qp_table.lock); + + if (send_cq != recv_cq) + spin_unlock(&recv_cq->lock); + spin_unlock_irq(&send_cq->lock); atomic_dec(&qp->refcount); wait_event(qp->wait, !atomic_read(&qp->refcount)); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/