[PATCH iwl-net v2 1/5] ice: check the auxiliary device pointer under adev_mutex

[Petr Oros <poros@redhat.com>]

ice_set_channels() and the mqprio path of ice_setup_tc() test
cdev->adev before taking pf->adev_mutex and dereference it afterwards.
ice_unplug_aux_dev() clears the pointer under the mutex from the
service task, from ice_prepare_for_reset() and from the devlink RoCE
and iWARP parameter handlers, none of which hold the RTNL lock, so the
pointer can go away between the test and the device_lock() call.

Take pf->adev_mutex first and test the pointer under it. Without a
device the mutex is released again and the rebuild runs unlocked as
before.

Fixes: a6a0974aae42 ("ice: Prevent set_channel from changing queues while RDMA active")
Fixes: 4b31fd4d77ff ("ice: Fix RDMA VSI removal during queue rebuild")
Signed-off-by: Petr Oros <poros@redhat.com>
---
v2:
- new patch, the pointer test raced with ice_unplug_aux_dev()
---
 drivers/net/ethernet/intel/ice/ice_ethtool.c | 22 +++++++++++++-------
 drivers/net/ethernet/intel/ice/ice_main.c    | 22 +++++++++++++-------
 2 files changed, 28 insertions(+), 16 deletions(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_ethtool.c b/drivers/net/ethernet/intel/ice/ice_ethtool.c
index bf9a821c543b7f..5482a64c81c95a 100644
--- a/drivers/net/ethernet/intel/ice/ice_ethtool.c
+++ b/drivers/net/ethernet/intel/ice/ice_ethtool.c
@@ -3888,6 +3888,7 @@ static int ice_vsi_set_dflt_rss_lut(struct ice_vsi *vsi, int req_rss_size)
 static int ice_set_channels(struct net_device *dev, struct ethtool_channels *ch)
 {
 	struct ice_netdev_priv *np = netdev_priv(dev);
+	struct auxiliary_device *adev = NULL;
 	struct ice_vsi *vsi = np->vsi;
 	struct ice_pf *pf = vsi->back;
 	int new_rx = 0, new_tx = 0;
@@ -3942,14 +3943,19 @@ static int ice_set_channels(struct net_device *dev, struct ethtool_channels *ch)
 		return -EINVAL;
 	}
 
-	if (pf->cdev_info && pf->cdev_info->adev) {
+	if (pf->cdev_info) {
 		mutex_lock(&pf->adev_mutex);
-		device_lock(&pf->cdev_info->adev->dev);
-		locked = true;
-		if (pf->cdev_info->adev->dev.driver) {
-			netdev_err(dev, "Cannot change channels when RDMA is active\n");
-			ret = -EBUSY;
-			goto adev_unlock;
+		adev = pf->cdev_info->adev;
+		if (adev) {
+			device_lock(&adev->dev);
+			locked = true;
+			if (adev->dev.driver) {
+				netdev_err(dev, "Cannot change channels when RDMA is active\n");
+				ret = -EBUSY;
+				goto adev_unlock;
+			}
+		} else {
+			mutex_unlock(&pf->adev_mutex);
 		}
 	}
 
@@ -3965,7 +3971,7 @@ static int ice_set_channels(struct net_device *dev, struct ethtool_channels *ch)
 
 adev_unlock:
 	if (locked) {
-		device_unlock(&pf->cdev_info->adev->dev);
+		device_unlock(&adev->dev);
 		mutex_unlock(&pf->adev_mutex);
 	}
 	return ret;
diff --git a/drivers/net/ethernet/intel/ice/ice_main.c b/drivers/net/ethernet/intel/ice/ice_main.c
index d88835482d3aac..984479f1e1f6d9 100644
--- a/drivers/net/ethernet/intel/ice/ice_main.c
+++ b/drivers/net/ethernet/intel/ice/ice_main.c
@@ -9406,6 +9406,7 @@ ice_setup_tc(struct net_device *netdev, enum tc_setup_type type,
 	struct ice_netdev_priv *np = netdev_priv(netdev);
 	enum flow_block_binder_type binder_type;
 	struct iidc_rdma_core_dev_info *cdev;
+	struct auxiliary_device *adev = NULL;
 	struct ice_pf *pf = np->vsi->back;
 	flow_setup_cb_t *flower_handler;
 	bool locked = false;
@@ -9438,14 +9439,19 @@ ice_setup_tc(struct net_device *netdev, enum tc_setup_type type,
 		}
 
 		cdev = pf->cdev_info;
-		if (cdev && cdev->adev) {
+		if (cdev) {
 			mutex_lock(&pf->adev_mutex);
-			device_lock(&cdev->adev->dev);
-			locked = true;
-			if (cdev->adev->dev.driver) {
-				netdev_err(netdev, "Cannot change qdisc when RDMA is active\n");
-				err = -EBUSY;
-				goto adev_unlock;
+			adev = cdev->adev;
+			if (adev) {
+				device_lock(&adev->dev);
+				locked = true;
+				if (adev->dev.driver) {
+					netdev_err(netdev, "Cannot change qdisc when RDMA is active\n");
+					err = -EBUSY;
+					goto adev_unlock;
+				}
+			} else {
+				mutex_unlock(&pf->adev_mutex);
 			}
 		}
 
@@ -9456,7 +9462,7 @@ ice_setup_tc(struct net_device *netdev, enum tc_setup_type type,
 
 adev_unlock:
 		if (locked) {
-			device_unlock(&cdev->adev->dev);
+			device_unlock(&adev->dev);
 			mutex_unlock(&pf->adev_mutex);
 		}
 		return err;
-- 
2.56.0