diff mbox series

[rdma-next,v3,1/2] net: mana: Change the function signature of mana_get_primary_netdev_rcu

Message ID 1741132802-26795-1-git-send-email-longli@linuxonhyperv.com (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series [rdma-next,v3,1/2] net: mana: Change the function signature of mana_get_primary_netdev_rcu | expand

Checks

Context Check Description
netdev/tree_selection success Not a local patch

Commit Message

Long Li March 5, 2025, midnight UTC 
From: Long Li <longli@microsoft.com>

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 by calling dev_put().

Signed-off-by: Long Li <longli@microsoft.com>
---
 drivers/infiniband/hw/mana/device.c           |  7 +++----
 drivers/net/ethernet/microsoft/mana/mana_en.c | 11 +++++++----
 include/net/mana/mana.h                       |  2 +-
 3 files changed, 11 insertions(+), 9 deletions(-)

Comments

Jakub Kicinski March 5, 2025, 1:28 a.m. UTC | #1 
On Tue,  4 Mar 2025 16:00:01 -0800 longli@linuxonhyperv.com wrote:
> +	dev_hold(ndev);

netdev_hold(), please
Long Li March 5, 2025, 4:28 a.m. UTC | #2 
> On Tue,  4 Mar 2025 16:00:01 -0800 longli@linuxonhyperv.com wrote:
> > +	dev_hold(ndev);
> 
> netdev_hold(), please

Will change to netdev_hold().

Is it mandatory to use a tracker, or is it okay to use NULL like the following code:
https://web.git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_main.c?h=v6.14-rc5#n837

Thanks,
Long
Jason Gunthorpe March 5, 2025, 6:50 p.m. UTC | #3 
On Tue, Mar 04, 2025 at 04:00:01PM -0800, longli@linuxonhyperv.com wrote:
>  
> -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)
>  {
>  	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;
>  
> +	rcu_read_lock();
> +
>  	/* 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
>  		ndev = ac->ports[port_index];
>  
> +	dev_hold(ndev);
> +	rcu_read_unlock();

That's much better, yes

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason
diff mbox series

Patch

diff --git a/drivers/infiniband/hw/mana/device.c b/drivers/infiniband/hw/mana/device.c
index 3416a85f8738..afe3d8d20b3b 100644
--- a/drivers/infiniband/hw/mana/device.c
+++ b/drivers/infiniband/hw/mana/device.c
@@ -84,10 +84,8 @@  static int mana_ib_probe(struct auxiliary_device *adev,
 	dev->ib_dev.num_comp_vectors = mdev->gdma_context->max_num_queues;
 	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);
 	if (!ndev) {
-		rcu_read_unlock();
 		ret = -ENODEV;
 		ibdev_err(&dev->ib_dev, "Failed to get netdev for IB port 1");
 		goto free_ib_device;
@@ -95,7 +93,8 @@  static int mana_ib_probe(struct auxiliary_device *adev,
 	ether_addr_copy(mac_addr, ndev->dev_addr);
 	addrconf_addr_eui48((u8 *)&dev->ib_dev.node_guid, ndev->dev_addr);
 	ret = ib_device_set_netdev(&dev->ib_dev, ndev, 1);
-	rcu_read_unlock();
+	/* mana_get_primary_netdev() returns ndev with refcount held */
+	dev_put(ndev);
 	if (ret) {
 		ibdev_err(&dev->ib_dev, "Failed to set ib netdev, ret %d", ret);
 		goto free_ib_device;
diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c b/drivers/net/ethernet/microsoft/mana/mana_en.c
index aa1e47233fe5..cfa664d5a137 100644
--- a/drivers/net/ethernet/microsoft/mana/mana_en.c
+++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
@@ -3131,21 +3131,24 @@  void mana_remove(struct gdma_dev *gd, bool suspending)
 	kfree(ac);
 }
 
-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)
 {
 	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;
 
+	rcu_read_lock();
+
 	/* 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
 		ndev = ac->ports[port_index];
 
+	dev_hold(ndev);
+	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 0d00b24eacaf..770359ce7d3b 100644
--- a/include/net/mana/mana.h
+++ b/include/net/mana/mana.h
@@ -827,5 +827,5 @@  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);
 #endif /* _MANA_H */