[PATCH V1 rdma-next 11/24] RDMA/mlx5: Introduce per-CQ poll_one hook in mlx5_ib_cq

[Yishai Hadas <yishaih@nvidia.com>]

Add a poll_one function pointer to struct mlx5_ib_cq and initialize it
to mlx5_poll_one in both mlx5_ib_create_cq() (kernel-ULP CQs) and
mlx5_ib_create_user_cq() (uverbs CQs, the path used by both the
modern ioctl-based and legacy write-based CQ creation commands).
mlx5_ib_poll_cq() is updated to dispatch through the pointer instead
of calling mlx5_poll_one() directly.

This is a pure refactor with no behaviour change. The indirection
allows a specialised poll_one implementation to be installed on a
specific CQ, which a follow-up patch uses to verify the UMR CQ against
a hostile NIC.

Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
---
 drivers/infiniband/hw/mlx5/cq.c      | 9 ++++++++-
 drivers/infiniband/hw/mlx5/mlx5_ib.h | 2 ++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/hw/mlx5/cq.c b/drivers/infiniband/hw/mlx5/cq.c
index 55ffd7d4de51..11c1153747c2 100644
--- a/drivers/infiniband/hw/mlx5/cq.c
+++ b/drivers/infiniband/hw/mlx5/cq.c
@@ -633,7 +633,7 @@ int mlx5_ib_poll_cq(struct ib_cq *ibcq, int num_entries, struct ib_wc *wc)
 		soft_polled = poll_soft_wc(cq, num_entries, wc, false);
 
 	for (npolled = 0; npolled < num_entries - soft_polled; npolled++) {
-		if (mlx5_poll_one(cq, &cur_qp, wc + soft_polled + npolled))
+		if (cq->poll_one(cq, &cur_qp, wc + soft_polled + npolled))
 			break;
 	}
 
@@ -1010,6 +1010,8 @@ int mlx5_ib_create_user_cq(struct ib_cq *ibcq,
 
 	cq->mcq.comp = mlx5_add_cq_to_tasklet;
 	cq->mcq.tasklet_ctx.comp = mlx5_ib_cq_comp;
+	/* Set before the CQ is created, see mlx5_ib_create_cq() */
+	cq->poll_one = mlx5_poll_one;
 
 	err = mlx5_core_create_cq(dev->mdev, &cq->mcq, cqb, inlen, out, sizeof(out));
 	if (err)
@@ -1093,6 +1095,11 @@ int mlx5_ib_create_cq(struct ib_cq *ibcq, const struct ib_cq_init_attr *attr,
 	MLX5_SET64(cqc, cqc, dbr_addr, cq->db.dma);
 
 	cq->mcq.comp = mlx5_ib_cq_comp;
+	/*
+	 * Set before mlx5_core_create_cq(). No real CQE can arrive before a
+	 * QP uses the CQ, but a forged one can make mlx5_ib_poll_cq() call it.
+	 */
+	cq->poll_one = mlx5_poll_one;
 
 	err = mlx5_core_create_cq(dev->mdev, &cq->mcq, cqb, inlen, out,
 				  sizeof(out));
diff --git a/drivers/infiniband/hw/mlx5/mlx5_ib.h b/drivers/infiniband/hw/mlx5/mlx5_ib.h
index 980b41800df5..4833f42b3fd1 100644
--- a/drivers/infiniband/hw/mlx5/mlx5_ib.h
+++ b/drivers/infiniband/hw/mlx5/mlx5_ib.h
@@ -592,6 +592,8 @@ struct mlx5_ib_cq {
 	enum ib_cq_notify_flags notify_flags;
 	struct work_struct	notify_work;
 	u16			private_flags; /* Use mlx5_ib_cq_pr_flags */
+	int (*poll_one)(struct mlx5_ib_cq *cq, struct mlx5_ib_qp **cur_qp,
+			struct ib_wc *wc);
 };
 
 struct mlx5_ib_wc {
-- 
2.18.1