[PATCH V1 rdma-next 08/15] RDMA/mlx5: Fix mlx5_ib_dev_res_init() failure when XRC cap is absent

[Yishai Hadas <yishaih@nvidia.com>]

mlx5_ib_dev_res_init() returns -EOPNOTSUPP when the firmware XRC
capability is absent, failing driver probe on XRC-less devices.

Make XRC optional throughout the devr resource path: initialize cq_lock
and srq_lock unconditionally (needed for every QP creation), skip xrcd
allocation and the XRC-type placeholder SRQ (s0) when xrc=0, and guard
their cleanup paths accordingly.

Fixes: f4375443b786 ("RDMA/mlx5: Get XRCD number directly for the internal use")
Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
---
 drivers/infiniband/hw/mlx5/main.c | 56 +++++++++++++++++++------------
 1 file changed, 34 insertions(+), 22 deletions(-)

diff --git a/drivers/infiniband/hw/mlx5/main.c b/drivers/infiniband/hw/mlx5/main.c
index 373ee1f42d4a..8b8a0f26cf19 100644
--- a/drivers/infiniband/hw/mlx5/main.c
+++ b/drivers/infiniband/hw/mlx5/main.c
@@ -3373,7 +3373,7 @@ int mlx5_ib_dev_res_srq_init(struct mlx5_ib_dev *dev)
 {
 	struct mlx5_ib_resources *devr = &dev->devr;
 	struct ib_srq_init_attr attr;
-	struct ib_srq *s0, *s1;
+	struct ib_srq *s0 = NULL, *s1;
 	int ret = 0;
 
 	/*
@@ -3391,19 +3391,27 @@ int mlx5_ib_dev_res_srq_init(struct mlx5_ib_dev *dev)
 	if (ret)
 		goto unlock;
 
-	memset(&attr, 0, sizeof(attr));
-	attr.attr.max_sge = 1;
-	attr.attr.max_wr = 1;
-	attr.srq_type = IB_SRQT_XRC;
-	attr.ext.cq = devr->c0;
-
-	s0 = ib_create_srq(devr->p0, &attr);
-	if (IS_ERR(s0)) {
-		ret = PTR_ERR(s0);
-		mlx5_ib_err(dev,
-			    "Couldn't create SRQ 0 for res init, err=%pe\n",
-			    s0);
-		goto unlock;
+	/*
+	 * s0 is an XRC-type placeholder SRQ used as the default XRQN for
+	 * XRC QPs.  Skip it when XRC is absent; all devr->s0 accesses in
+	 * qp.c are inside XRC QP paths that the verbs layer blocks before
+	 * reaching this driver when xrc=0, so NULL is safe.
+	 */
+	if (MLX5_CAP_GEN(dev->mdev, xrc)) {
+		memset(&attr, 0, sizeof(attr));
+		attr.attr.max_sge = 1;
+		attr.attr.max_wr = 1;
+		attr.srq_type = IB_SRQT_XRC;
+		attr.ext.cq = devr->c0;
+
+		s0 = ib_create_srq(devr->p0, &attr);
+		if (IS_ERR(s0)) {
+			ret = PTR_ERR(s0);
+			mlx5_ib_err(dev,
+				    "Couldn't create SRQ 0 for res init, err=%pe\n",
+				    s0);
+			goto unlock;
+		}
 	}
 
 	memset(&attr, 0, sizeof(attr));
@@ -3417,7 +3425,8 @@ int mlx5_ib_dev_res_srq_init(struct mlx5_ib_dev *dev)
 		mlx5_ib_err(dev,
 			    "Couldn't create SRQ 1 for res init, err=%pe\n",
 			    s1);
-		ib_destroy_srq(s0);
+		if (s0)
+			ib_destroy_srq(s0);
 		goto unlock;
 	}
 
@@ -3434,8 +3443,11 @@ static int mlx5_ib_dev_res_init(struct mlx5_ib_dev *dev)
 	struct mlx5_ib_resources *devr = &dev->devr;
 	int ret;
 
+	mutex_init(&devr->cq_lock);
+	mutex_init(&devr->srq_lock);
+
 	if (!MLX5_CAP_GEN(dev->mdev, xrc))
-		return -EOPNOTSUPP;
+		return 0;
 
 	ret = mlx5_cmd_xrcd_alloc(dev->mdev, &devr->xrcdn0, 0);
 	if (ret)
@@ -3447,9 +3459,6 @@ static int mlx5_ib_dev_res_init(struct mlx5_ib_dev *dev)
 		return ret;
 	}
 
-	mutex_init(&devr->cq_lock);
-	mutex_init(&devr->srq_lock);
-
 	return 0;
 }
 
@@ -3460,10 +3469,13 @@ static void mlx5_ib_dev_res_cleanup(struct mlx5_ib_dev *dev)
 	/* After s0/s1 init, they are not unset during the device lifetime. */
 	if (devr->s1) {
 		ib_destroy_srq(devr->s1);
-		ib_destroy_srq(devr->s0);
+		if (devr->s0)
+			ib_destroy_srq(devr->s0);
+	}
+	if (MLX5_CAP_GEN(dev->mdev, xrc)) {
+		mlx5_cmd_xrcd_dealloc(dev->mdev, devr->xrcdn1, 0);
+		mlx5_cmd_xrcd_dealloc(dev->mdev, devr->xrcdn0, 0);
 	}
-	mlx5_cmd_xrcd_dealloc(dev->mdev, devr->xrcdn1, 0);
-	mlx5_cmd_xrcd_dealloc(dev->mdev, devr->xrcdn0, 0);
 	/* After p0/c0 init, they are not unset during the device lifetime. */
 	if (devr->c0) {
 		ib_destroy_cq(devr->c0);
-- 
2.18.1