Re: [PATCH net-next v5 3/3] net: airoha: defer GDM3/GDM4 WAN mode and GDM2 loopback to QoS offload

[Lorenzo Bianconi <lorenzo@kernel.org>]

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Commenting on sashiko's report:
https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260611-airoha-ethtool-priv_flags-v5-0-c11de08486d1%40kernel.org

[...]

> +static int airoha_enable_qos_for_gdm34(struct net_device *netdev,
> +				       struct netlink_ext_ack *extack)
> +{
> +	struct airoha_gdm_dev *wan_dev, *dev = netdev_priv(netdev);
> +	struct airoha_gdm_port *port = dev->port;
> +	struct airoha_eth *eth = dev->eth;
> +	int err = -EBUSY;
> +
> +	if (port->id != AIROHA_GDM3_IDX &&
> +	    port->id != AIROHA_GDM4_IDX) {
> +		/* HW QoS is always supported by GDM1 and GDM2 */
> +		return 0;
> +	}
> +
> +	if (!airoha_is_lan_gdm_dev(dev)) /* Already enabled */
> +		return 0;
> +
> +	mutex_lock(&flow_offload_mutex);
> +
> +	wan_dev = airoha_get_wan_gdm_dev(eth);
> +	if (wan_dev) {
> +		if ((wan_dev->flags & AIROHA_PRIV_F_QOS) ||
> +		    wan_dev->port->id == AIROHA_GDM2_IDX) {
> +			NL_SET_ERR_MSG_MOD(extack,
> +					   "QoS configured for WAN device");
> +			goto error_unlock;
> +		}
> +		airoha_disable_qos_for_gdm34(netdev_from_priv(wan_dev));
> +	}
> +
> +	dev->flags |= AIROHA_PRIV_F_WAN;
> +	airoha_dev_set_qdma(dev);
> +	err = airoha_enable_gdm2_loopback(dev);
> +	if (err)
> +		goto error_disable_wan;
> +
> +	err = airoha_set_macaddr(dev, netdev->dev_addr);
> +	if (err)
> +		goto error_disable_loopback;
> +
> +	if (netif_running(netdev)) {
> +		u32 pse_port;
> +
> +		pse_port = airoha_ppe_is_enabled(eth, 1) ? FE_PSE_PORT_PPE2
> +							 : FE_PSE_PORT_PPE1;
> +		airoha_set_gdm_port_fwd_cfg(eth, REG_GDM_FWD_CFG(port->id),
> +					    pse_port);
> +	}
> +
> +	mutex_unlock(&flow_offload_mutex);
> +
> +	return 0;
> +
> +error_disable_loopback:
> +	airoha_disable_gdm2_loopback(dev);
> +error_disable_wan:
> +	dev->flags &= ~AIROHA_PRIV_F_WAN;
> +	airoha_dev_set_qdma(dev);
> +error_unlock:
> +	mutex_unlock(&flow_offload_mutex);
> +
> +	return err;
> +}

- The error_disable_loopback / error_disable_wan / error_unlock paths only
  revert the requesting dev. The earlier airoha_disable_qos_for_gdm34(wan_dev)
  demotion is never undone.
  Could a TC_HTB_CREATE that returns an error to userspace then leave the
  system with no WAN GDM3/GDM4 device, with the previously-working sibling
  silently flipped to LAN, its QDMA migrated to QDMA0, GDM2 loopback torn
  down, and its forwarding rewritten to PPE1?
  Should the failure paths re-promote wan_dev (re-call airoha_enable_qos_for_gdm34
  or an equivalent restore helper on it) before unlocking and returning?

  - This is the same item reported by sashiko-gemini in [0]. In my previous
    reply I have explained why I do not think it worths to re-promote the
    original interface in case of failure in airoha_enable_qos_for_gdm34().

Regards,
Lorenzo


[0] https://sashiko.dev/#/patchset/20260611-airoha-ethtool-priv_flags-v5-0-c11de08486d1%40kernel.org

> +
>  static int airoha_tc_htb_destroy(struct net_device *netdev)
>  {
>  	struct airoha_gdm_dev *dev = netdev_priv(netdev);
> @@ -3038,6 +3205,8 @@ static int airoha_tc_htb_destroy(struct net_device *netdev)
>  	for_each_set_bit(q, dev->qos_sq_bmap, AIROHA_NUM_QOS_CHANNELS)
>  		airoha_tc_remove_htb_queue(netdev, q);
>  
> +	dev->flags &= ~AIROHA_PRIV_F_QOS;
> +
>  	return 0;
>  }
>  
> @@ -3057,24 +3226,33 @@ static int airoha_tc_get_htb_get_leaf_queue(struct net_device *netdev,
>  	return 0;
>  }
>  
> -static int airoha_tc_setup_qdisc_htb(struct net_device *dev,
> +static int airoha_tc_setup_qdisc_htb(struct net_device *netdev,
>  				     struct tc_htb_qopt_offload *opt)
>  {
>  	switch (opt->command) {
> -	case TC_HTB_CREATE:
> +	case TC_HTB_CREATE: {
> +		struct airoha_gdm_dev *dev = netdev_priv(netdev);
> +		int err;
> +
> +		err = airoha_enable_qos_for_gdm34(netdev, opt->extack);
> +		if (err)
> +			return err;
> +
> +		dev->flags |= AIROHA_PRIV_F_QOS;
>  		break;
> +	}
>  	case TC_HTB_DESTROY:
> -		return airoha_tc_htb_destroy(dev);
> +		return airoha_tc_htb_destroy(netdev);
>  	case TC_HTB_NODE_MODIFY:
> -		return airoha_tc_htb_modify_queue(dev, opt);
> +		return airoha_tc_htb_modify_queue(netdev, opt);
>  	case TC_HTB_LEAF_ALLOC_QUEUE:
> -		return airoha_tc_htb_alloc_leaf_queue(dev, opt);
> +		return airoha_tc_htb_alloc_leaf_queue(netdev, opt);
>  	case TC_HTB_LEAF_DEL:
>  	case TC_HTB_LEAF_DEL_LAST:
>  	case TC_HTB_LEAF_DEL_LAST_FORCE:
> -		return airoha_tc_htb_delete_leaf_queue(dev, opt);
> +		return airoha_tc_htb_delete_leaf_queue(netdev, opt);
>  	case TC_HTB_LEAF_QUERY_QUEUE:
> -		return airoha_tc_get_htb_get_leaf_queue(dev, opt);
> +		return airoha_tc_get_htb_get_leaf_queue(netdev, opt);
>  	default:
>  		return -EOPNOTSUPP;
>  	}
> diff --git a/drivers/net/ethernet/airoha/airoha_eth.h b/drivers/net/ethernet/airoha/airoha_eth.h
> index 24fd8dcf7fca..d1390ffcea7c 100644
> --- a/drivers/net/ethernet/airoha/airoha_eth.h
> +++ b/drivers/net/ethernet/airoha/airoha_eth.h
> @@ -540,11 +540,12 @@ struct airoha_qdma {
>  
>  enum airoha_priv_flags {
>  	AIROHA_PRIV_F_WAN = BIT(0),
> +	AIROHA_PRIV_F_QOS = BIT(1),
>  };
>  
>  struct airoha_gdm_dev {
> +	struct airoha_qdma __rcu *qdma;
>  	struct airoha_gdm_port *port;
> -	struct airoha_qdma *qdma;
>  	struct airoha_eth *eth;
>  
>  	DECLARE_BITMAP(qos_sq_bmap, AIROHA_NUM_QOS_CHANNELS);
> @@ -676,6 +677,16 @@ int airoha_get_fe_port(struct airoha_gdm_dev *dev);
>  bool airoha_is_valid_gdm_dev(struct airoha_eth *eth,
>  			     struct airoha_gdm_dev *dev);
>  
> +extern struct mutex flow_offload_mutex;
> +
> +static inline struct airoha_qdma *
> +airoha_qdma_deref(struct airoha_gdm_dev *dev)
> +{
> +	return rcu_dereference_protected(dev->qdma,
> +					 lockdep_rtnl_is_held() ||
> +					 lockdep_is_held(&flow_offload_mutex));
> +}
> +
>  void airoha_ppe_set_cpu_port(struct airoha_gdm_dev *dev, u8 ppe_id, u8 fport);
>  bool airoha_ppe_is_enabled(struct airoha_eth *eth, int index);
>  void airoha_ppe_check_skb(struct airoha_ppe_dev *dev, struct sk_buff *skb,
> diff --git a/drivers/net/ethernet/airoha/airoha_ppe.c b/drivers/net/ethernet/airoha/airoha_ppe.c
> index 91bcc55a6ac6..1d1b1a57d795 100644
> --- a/drivers/net/ethernet/airoha/airoha_ppe.c
> +++ b/drivers/net/ethernet/airoha/airoha_ppe.c
> @@ -15,7 +15,10 @@
>  #include "airoha_regs.h"
>  #include "airoha_eth.h"
>  
> -static DEFINE_MUTEX(flow_offload_mutex);
> +/* Serialize airoha_gdm_dev flags, QDMA pointer and PPE CPU port
> + * configuration.
> + */
> +DEFINE_MUTEX(flow_offload_mutex);
>  static DEFINE_SPINLOCK(ppe_lock);
>  
>  static const struct rhashtable_params airoha_flow_table_params = {
> @@ -86,8 +89,8 @@ static u32 airoha_ppe_get_timestamp(struct airoha_ppe *ppe)
>  
>  void airoha_ppe_set_cpu_port(struct airoha_gdm_dev *dev, u8 ppe_id, u8 fport)
>  {
> -	struct airoha_qdma *qdma = dev->qdma;
> -	struct airoha_eth *eth = qdma->eth;
> +	struct airoha_qdma *qdma = airoha_qdma_deref(dev);
> +	struct airoha_eth *eth = dev->eth;
>  	u8 qdma_id = qdma - &eth->qdma[0];
>  	u32 fe_cpu_port;
>  
> diff --git a/drivers/net/ethernet/airoha/airoha_regs.h b/drivers/net/ethernet/airoha/airoha_regs.h
> index 436f3c8779c1..4e17dfbcf2b8 100644
> --- a/drivers/net/ethernet/airoha/airoha_regs.h
> +++ b/drivers/net/ethernet/airoha/airoha_regs.h
> @@ -376,6 +376,7 @@
>  
>  #define REG_SRC_PORT_FC_MAP6		0x2298
>  #define FC_ID_OF_SRC_PORT_MASK(_n)	GENMASK(4 + ((_n) << 3), ((_n) << 3))
> +#define FC_MAP6_DEF_VALUE		0x1b1a1918
>  
>  #define REG_CDM5_RX_OQ1_DROP_CNT	0x29d4
>  
> 
> -- 
> 2.54.0
> 

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