[PATCH 3.16 132/410] IB/mlx4: Fix incorrectly releasing steerable UD QPs when have only ETH ports

[Ben Hutchings]

3.16.57-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Jack Morgenstein <jackm@xxxxxxxxxxxxxxxxxx>

commit 852f6927594d0d3e8632c889b2ab38cbc46476ad upstream.

Allocating steerable UD QPs depends on having at least one IB port,
while releasing those QPs does not.

As a result, when there are only ETH ports, the IB (RoCE) driver
requests releasing a qp range whose base qp is zero, with
qp count zero.

When SR-IOV is enabled, and the VF driver is running on a VM over
a hypervisor which treats such qp release calls as errors
(rather than NOPs), we see lines in the VM message log like:

 mlx4_core 0002:00:02.0: Failed to release qp range base:0 cnt:0

Fix this by adding a check for a zero count in mlx4_release_qp_range()
(which thus treats releasing 0 qps as a nop), and eliminating the
check for device managed flow steering when releasing steerable UD QPs.
(Freeing ib_uc_qpns_bitmap unconditionally is also OK, since it
remains NULL when steerable UD QPs are not allocated).

Fixes: 4196670be786 ("IB/mlx4: Don't allocate range of steerable UD QPs for Ethernet-only device")
Signed-off-by: Jack Morgenstein <jackm@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Leon Romanovsky <leon@xxxxxxxxxx>
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/infiniband/hw/mlx4/main.c       | 13 +++++--------
 drivers/net/ethernet/mellanox/mlx4/qp.c |  3 +++
 2 files changed, 8 insertions(+), 8 deletions(-)

--- a/drivers/infiniband/hw/mlx4/main.c
+++ b/drivers/infiniband/hw/mlx4/main.c
@@ -2272,9 +2272,8 @@ err_steer_free_bitmap:
 	kfree(ibdev->ib_uc_qpns_bitmap);
 
 err_steer_qp_release:
-	if (ibdev->steering_support == MLX4_STEERING_MODE_DEVICE_MANAGED)
-		mlx4_qp_release_range(dev, ibdev->steer_qpn_base,
-				      ibdev->steer_qpn_count);
+	mlx4_qp_release_range(dev, ibdev->steer_qpn_base,
+			      ibdev->steer_qpn_count);
 err_counter:
 	for (; i; --i)
 		if (ibdev->counters[i - 1] != -1)
@@ -2373,11 +2372,9 @@ static void mlx4_ib_remove(struct mlx4_d
 		ibdev->iboe.nb.notifier_call = NULL;
 	}
 
-	if (ibdev->steering_support == MLX4_STEERING_MODE_DEVICE_MANAGED) {
-		mlx4_qp_release_range(dev, ibdev->steer_qpn_base,
-				      ibdev->steer_qpn_count);
-		kfree(ibdev->ib_uc_qpns_bitmap);
-	}
+	mlx4_qp_release_range(dev, ibdev->steer_qpn_base,
+			      ibdev->steer_qpn_count);
+	kfree(ibdev->ib_uc_qpns_bitmap);
 
 	if (ibdev->iboe.nb_inet.notifier_call) {
 		if (unregister_inetaddr_notifier(&ibdev->iboe.nb_inet))
--- a/drivers/net/ethernet/mellanox/mlx4/qp.c
+++ b/drivers/net/ethernet/mellanox/mlx4/qp.c
@@ -257,6 +257,9 @@ void mlx4_qp_release_range(struct mlx4_d
 	u64 in_param = 0;
 	int err;
 
+	if (!cnt)
+		return;
+
 	if (mlx4_is_mfunc(dev)) {
 		set_param_l(&in_param, base_qpn);
 		set_param_h(&in_param, cnt);