[SRU][N:linux-azure][PATCH 2/3] net: mana: Change the function signature of mana_get_primary_netdev_rcu

[John Cabaj]

From: Long Li <longli at microsoft.com>

BugLink: https://bugs.launchpad.net/bugs/2119572

Change mana_get_primary_netdev_rcu() to mana_get_primary_netdev(), and
return the ndev with refcount held. The caller is responsible for dropping
the refcount.

Also drop the check for IFF_SLAVE as it is not necessary if the upper
device is present.

Signed-off-by: Long Li <longli at microsoft.com>
Link: https://patch.msgid.link/1741821332-9392-1-git-send-email-longli@linuxonhyperv.com
Signed-off-by: Leon Romanovsky <leon at kernel.org>
(backported from commit a8445cfec101c42e9d64cdb2dac13973b22c205c)
[john-cabaj: leaving out unnecessary struct dma_pool *av_pool and
reverting stringified namespace]
Signed-off-by: John Cabaj <john.cabaj at canonical.com>
---
 drivers/infiniband/hw/mana/device.c           |  7 +++---
 drivers/infiniband/hw/mana/mana_ib.h          |  1 +
 drivers/net/ethernet/microsoft/mana/mana_en.c | 22 ++++++++++++-------
 include/net/mana/mana.h                       |  4 +++-
 4 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/drivers/infiniband/hw/mana/device.c b/drivers/infiniband/hw/mana/device.c
index 648bb31c8682..d69204e00e4a 100644
--- a/drivers/infiniband/hw/mana/device.c
+++ b/drivers/infiniband/hw/mana/device.c
@@ -78,16 +78,15 @@ static int mana_ib_probe(struct auxiliary_device *adev,
 	dev->ib_dev.num_comp_vectors = 1;
 	dev->ib_dev.dev.parent = mdev->gdma_context->dev;
 
-	rcu_read_lock(); /* required to get primary netdev */
-	ndev = mana_get_primary_netdev_rcu(mc, 0);
+	ndev = mana_get_primary_netdev(mc, 0, &dev->dev_tracker);
 	if (!ndev) {
-		rcu_read_unlock();
 		ret = -ENODEV;
 		ibdev_err(&dev->ib_dev, "Failed to get netdev for IB port 1");
 		goto free_ib_device;
 	}
 	ret = ib_device_set_netdev(&dev->ib_dev, ndev, 1);
-	rcu_read_unlock();
+	/* mana_get_primary_netdev() returns ndev with refcount held */
+	netdev_put(ndev, &dev->dev_tracker);
 	if (ret) {
 		ibdev_err(&dev->ib_dev, "Failed to set ib netdev, ret %d", ret);
 		goto free_ib_device;
diff --git a/drivers/infiniband/hw/mana/mana_ib.h b/drivers/infiniband/hw/mana/mana_ib.h
index 6acb5c281c36..a056b51475ee 100644
--- a/drivers/infiniband/hw/mana/mana_ib.h
+++ b/drivers/infiniband/hw/mana/mana_ib.h
@@ -55,6 +55,7 @@ struct mana_ib_dev {
 	struct ib_device ib_dev;
 	struct gdma_dev *gdma_dev;
 	struct mana_ib_adapter_caps adapter_caps;
+	netdevice_tracker dev_tracker;
 };
 
 struct mana_ib_wq {
diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c b/drivers/net/ethernet/microsoft/mana/mana_en.c
index 89ef53b4d2d1..39bd924530cb 100644
--- a/drivers/net/ethernet/microsoft/mana/mana_en.c
+++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
@@ -3185,21 +3185,27 @@ void mana_remove(struct gdma_dev *gd, bool suspending)
 	dev_dbg(dev, "%s succeeded\n", __func__);
 }
 
-struct net_device *mana_get_primary_netdev_rcu(struct mana_context *ac, u32 port_index)
+struct net_device *mana_get_primary_netdev(struct mana_context *ac,
+					   u32 port_index,
+					   netdevice_tracker *tracker)
 {
 	struct net_device *ndev;
 
-	RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
-			 "Taking primary netdev without holding the RCU read lock");
 	if (port_index >= ac->num_ports)
 		return NULL;
 
-	/* When mana is used in netvsc, the upper netdevice should be returned. */
-	if (ac->ports[port_index]->flags & IFF_SLAVE)
-		ndev = netdev_master_upper_dev_get_rcu(ac->ports[port_index]);
-	else
+	rcu_read_lock();
+
+	/* If mana is used in netvsc, the upper netdevice should be returned. */
+	ndev = netdev_master_upper_dev_get_rcu(ac->ports[port_index]);
+
+	/* If there is no upper device, use the parent Ethernet device */
+	if (!ndev)
 		ndev = ac->ports[port_index];
 
+	netdev_hold(ndev, tracker, GFP_ATOMIC);
+	rcu_read_unlock();
+
 	return ndev;
 }
-EXPORT_SYMBOL_NS(mana_get_primary_netdev_rcu, NET_MANA);
+EXPORT_SYMBOL_NS(mana_get_primary_netdev, NET_MANA);
diff --git a/include/net/mana/mana.h b/include/net/mana/mana.h
index 23edf649e65a..2e08c68a7fb4 100644
--- a/include/net/mana/mana.h
+++ b/include/net/mana/mana.h
@@ -828,5 +828,7 @@ int mana_cfg_vport(struct mana_port_context *apc, u32 protection_dom_id,
 		   u32 doorbell_pg_id);
 void mana_uncfg_vport(struct mana_port_context *apc);
 
-struct net_device *mana_get_primary_netdev_rcu(struct mana_context *ac, u32 port_index);
+struct net_device *mana_get_primary_netdev(struct mana_context *ac,
+					   u32 port_index,
+					   netdevice_tracker *tracker);
 #endif /* _MANA_H */
-- 
2.43.0