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([2620:10d:c091:500::1:63f7]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-5070d510ab5sm106352601cf.4.2026.02.24.12.58.28 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 24 Feb 2026 12:58:28 -0800 (PST) Message-ID: <0a850f65-be67-4a66-941f-17d8440e987b@gmail.com> Date: Tue, 24 Feb 2026 15:58:27 -0500 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [net-next, v2 1/2] psp: Support for transmit on logical device when the underlying transport device supports PSP. To: Kiran Kella , davem@davemloft.net, edumazet@google.com, kuba@kernel.org, willemb@google.com, pabeni@redhat.com, andrew+netdev@lunn.ch, horms@kernel.org Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, jayakrishnan.udayavarma@broadcom.com, ajit.khaparde@broadcom.com, akhilesh.samineni@broadcom.com References: <20260223191154.2800616-1-kiran.kella@broadcom.com> <20260223191154.2800616-2-kiran.kella@broadcom.com> Content-Language: en-US From: Daniel Zahka In-Reply-To: <20260223191154.2800616-2-kiran.kella@broadcom.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2/23/26 2:11 PM, Kiran Kella wrote: > This is achieved by propagating the psp_dev from the lower device > to the upper devices in the device stack via a netdevice notifier. > The lowest device owns the psp_dev pointer while the upper devices > just borrow the pointer. When the lower device is unlinked, the > borrowed pointer is cleared in the upper device. > Assumption being that psp_dev is set on the lowest device before > any upper devices are stacked on that lowest device. > > Signed-off-by: Kiran Kella > Reviewed-by: Ajit Kumar Khaparde > Reviewed-by: Akhilesh Samineni > --- > net/psp/psp_main.c | 109 ++++++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 108 insertions(+), 1 deletion(-) > > diff --git a/net/psp/psp_main.c b/net/psp/psp_main.c > index a8534124f626..fac785dcfa0f 100644 > --- a/net/psp/psp_main.c > +++ b/net/psp/psp_main.c > @@ -3,6 +3,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -110,13 +111,45 @@ void psp_dev_free(struct psp_dev *psd) > kfree_rcu(psd, rcu); > } > > +/** > + * psp_clear_upper_dev_psp_dev() - Clear borrowed psp_dev pointer on upper > + * device > + * @upper_dev: Upper device that may have borrowed psp_dev pointer > + * @priv: netdev_nested_priv containing the psp_dev being unregistered > + * > + * Callback for netdev_walk_all_upper_dev_rcu() to clear borrowed psp_dev > + * pointers on upper devices when the underlying psp_dev is being unregistered. > + * > + * Return: 0 to continue walking, non-zero to stop. > + */ > +static int psp_clear_upper_dev_psp_dev(struct net_device *upper_dev, > + struct netdev_nested_priv *priv) > +{ > + struct psp_dev *psd = priv->data; > + struct psp_dev *upper_psd; > + > + upper_psd = rcu_dereference(upper_dev->psp_dev); > + if (upper_psd == psd) > + rcu_assign_pointer(upper_dev->psp_dev, NULL); > + > + return 0; > +} > + > /** > * psp_dev_unregister() - unregister PSP device > * @psd: PSP device structure > + * > + * Unregisters a PSP device and clears all borrowed psp_dev pointers on > + * upper devices (e.g., VLAN subinterfaces) that reference this device. > + * This prevents use-after-free if upper devices still have borrowed > + * pointers when the psp_dev structure is freed. > */ > void psp_dev_unregister(struct psp_dev *psd) > { > struct psp_assoc *pas, *next; > + struct netdev_nested_priv priv = { > + .data = psd, > + }; > > mutex_lock(&psp_devs_lock); > mutex_lock(&psd->lock); > @@ -137,6 +170,12 @@ void psp_dev_unregister(struct psp_dev *psd) > > rcu_assign_pointer(psd->main_netdev->psp_dev, NULL); > > + /* Clear borrowed psp_dev pointers on all upper devices */ > + rcu_read_lock(); > + netdev_walk_all_upper_dev_rcu(psd->main_netdev, > + psp_clear_upper_dev_psp_dev, &priv); > + rcu_read_unlock(); > + > psd->ops = NULL; > psd->drv_priv = NULL; > > @@ -313,11 +352,79 @@ int psp_dev_rcv(struct sk_buff *skb, u16 dev_id, u8 generation, bool strip_icv) > } > EXPORT_SYMBOL(psp_dev_rcv); > > +/** > + * psp_netdevice_event() - Handle netdevice events for PSP device propagation > + * @nb: notifier block > + * @event: netdevice event > + * @ptr: netdevice notifier info > + * > + * Propagates psp_dev pointer from lower devices to upper devices when > + * upper devices are created (e.g., VLAN subinterfaces). > + * Excluding from this logic, the upper devices that have multiple lower > + * devices eg., bond devices. > + * > + * Return: NOTIFY_DONE > + */ > +static int psp_netdevice_event(struct notifier_block *nb, > + unsigned long event, void *ptr) > +{ > + struct netdev_notifier_changeupper_info *info; > + struct net_device *dev, *upper_dev; > + struct psp_dev *psd; > + > + if (event != NETDEV_CHANGEUPPER) > + return NOTIFY_DONE; > + > + info = ptr; > + dev = netdev_notifier_info_to_dev(ptr); > + upper_dev = info->upper_dev; > + > + if (netif_is_lag_master(upper_dev)) > + return NOTIFY_DONE; > + > + if (info->linking) { > + /* Lower device is being linked to an upper device. > + * Propagate psp_dev from the immediate lower device to the > + * upper device. The immediate lower device would have already > + * got the psp_dev pointer set in a previous notification (or > + * owns it if it's the lowest device). > + * Upper devices just borrow the pointer. > + */ > + psd = rtnl_dereference(dev->psp_dev); > + if (psd) > + rcu_assign_pointer(upper_dev->psp_dev, psd); > + } else { > + /* Lower device is being unlinked from an upper device. > + * Clear the borrowed psp_dev pointer. > + */ > + psd = rtnl_dereference(upper_dev->psp_dev); > + if (psd) > + rcu_assign_pointer(upper_dev->psp_dev, NULL); > + } > + > + return NOTIFY_DONE; > +} > + > +static struct notifier_block psp_netdevice_notifier = { > + .notifier_call = psp_netdevice_event, > +}; > + > static int __init psp_init(void) > { > + int err; > + > mutex_init(&psp_devs_lock); > > - return genl_register_family(&psp_nl_family); > + err = register_netdevice_notifier(&psp_netdevice_notifier); > + if (err) > + return err; > + > + err = genl_register_family(&psp_nl_family); > + if (err) { > + unregister_netdevice_notifier(&psp_netdevice_notifier); > + return err; > + } > + return 0; > } > > subsys_initcall(psp_init); The lack of support for netns is a bit of a gap for this feature. It may make sense to see if what was posted in https://lore.kernel.org/netdev/20260224002410.1553838-1-weibunny@fb.com/ is sufficient for your use case, as it handles cases where upper devices are in a different netns from psd->main_netdev.