[dpdk-stable] [dpdk-dev] [PATCH] net/ixgbe: fix busy polling while fiber link update

[Zhang, Qi Z]

Hi Ilya:

> -----Original Message-----
> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Ilya Maximets
> Sent: Friday, August 31, 2018 8:40 PM
> To: dev at dpdk.org
> Cc: Lu, Wenzhuo <wenzhuo.lu at intel.com>; Ananyev, Konstantin
> <konstantin.ananyev at intel.com>; Laurent Hardy
> <laurent.hardy at 6wind.com>; Dai, Wei <wei.dai at intel.com>; Ilya Maximets
> <i.maximets at samsung.com>; stable at dpdk.org
> Subject: [dpdk-dev] [PATCH] net/ixgbe: fix busy polling while fiber link update
> 
> If the multispeed fiber link is in DOWN state, ixgbe_setup_link could take
> around a second of busy polling. This is highly inconvenient for the case where
> single thread periodically checks the link statuses. For example, OVS main
> thread periodically updates the link statuses and hangs for a really long time
> busy waiting on ixgbe_setup_link() for a DOWN fiber ports. For case with 3
> down ports it hangs for a 3 seconds and unable to do anything including
> packet processing.
> Fix that by shifting that workaround to a separate thread by alarm handler that
> will try to set up link if it is DOWN.

Does that mean we will block the interrupt thread for 3 seconds?
Also, can we guarantee there will not be any race condition if we call ixgbe_setup_link at another thread, the base code API is not assumed to be thread-safe as I know.

Regards
Qi

> 
> Fixes: c12d22f65b13 ("net/ixgbe: ensure link status is updated")
> CC: stable at dpdk.org
> 
> Signed-off-by: Ilya Maximets <i.maximets at samsung.com>
> ---
>  drivers/net/ixgbe/ixgbe_ethdev.c | 43 ++++++++++++++++++++++++--------
>  1 file changed, 32 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/net/ixgbe/ixgbe_ethdev.c
> b/drivers/net/ixgbe/ixgbe_ethdev.c
> index 26b192737..a33b9a6e8 100644
> --- a/drivers/net/ixgbe/ixgbe_ethdev.c
> +++ b/drivers/net/ixgbe/ixgbe_ethdev.c
> @@ -221,6 +221,8 @@ static int ixgbe_dev_interrupt_action(struct
> rte_eth_dev *dev,
>  				      struct rte_intr_handle *handle);  static void
> ixgbe_dev_interrupt_handler(void *param);  static void
> ixgbe_dev_interrupt_delayed_handler(void *param);
> +static void ixgbe_dev_setup_link_alarm_handler(void *param);
> +
>  static int ixgbe_add_rar(struct rte_eth_dev *dev, struct ether_addr
> *mac_addr,
>  			 uint32_t index, uint32_t pool);
>  static void ixgbe_remove_rar(struct rte_eth_dev *dev, uint32_t index); @@
> -2791,6 +2793,8 @@ ixgbe_dev_stop(struct rte_eth_dev *dev)
> 
>  	PMD_INIT_FUNC_TRACE();
> 
> +	rte_eal_alarm_cancel(ixgbe_dev_setup_link_alarm_handler, dev);
> +
>  	/* disable interrupts */
>  	ixgbe_disable_intr(hw);
> 
> @@ -3969,6 +3973,25 @@ ixgbevf_check_link(struct ixgbe_hw *hw,
> ixgbe_link_speed *speed,
>  	return ret_val;
>  }
> 
> +static void
> +ixgbe_dev_setup_link_alarm_handler(void *param) {
> +	struct rte_eth_dev *dev = (struct rte_eth_dev *)param;
> +	struct ixgbe_hw *hw =
> IXGBE_DEV_PRIVATE_TO_HW(dev->data->dev_private);
> +	struct ixgbe_interrupt *intr =
> +		IXGBE_DEV_PRIVATE_TO_INTR(dev->data->dev_private);
> +	u32 speed;
> +	bool autoneg = false;
> +
> +	speed = hw->phy.autoneg_advertised;
> +	if (!speed)
> +		ixgbe_get_link_capabilities(hw, &speed, &autoneg);
> +
> +	ixgbe_setup_link(hw, speed, true);
> +
> +	intr->flags &= ~IXGBE_FLAG_NEED_LINK_CONFIG; }
> +
>  /* return 0 means link status changed, -1 means not changed */  int
> ixgbe_dev_link_update_share(struct rte_eth_dev *dev, @@ -3981,9 +4004,7
> @@ ixgbe_dev_link_update_share(struct rte_eth_dev *dev,
>  		IXGBE_DEV_PRIVATE_TO_INTR(dev->data->dev_private);
>  	int link_up;
>  	int diag;
> -	u32 speed = 0;
>  	int wait = 1;
> -	bool autoneg = false;
> 
>  	memset(&link, 0, sizeof(link));
>  	link.link_status = ETH_LINK_DOWN;
> @@ -3993,13 +4014,8 @@ ixgbe_dev_link_update_share(struct rte_eth_dev
> *dev,
> 
>  	hw->mac.get_link_status = true;
> 
> -	if ((intr->flags & IXGBE_FLAG_NEED_LINK_CONFIG) &&
> -		ixgbe_get_media_type(hw) == ixgbe_media_type_fiber) {
> -		speed = hw->phy.autoneg_advertised;
> -		if (!speed)
> -			ixgbe_get_link_capabilities(hw, &speed, &autoneg);
> -		ixgbe_setup_link(hw, speed, true);
> -	}
> +	if (intr->flags & IXGBE_FLAG_NEED_LINK_CONFIG)
> +		return rte_eth_linkstatus_set(dev, &link);
> 
>  	/* check if it needs to wait to complete, if lsc interrupt is enabled */
>  	if (wait_to_complete == 0 || dev->data->dev_conf.intr_conf.lsc != 0) @@
> -4017,11 +4033,14 @@ ixgbe_dev_link_update_share(struct rte_eth_dev *dev,
>  	}
> 
>  	if (link_up == 0) {
> -		intr->flags |= IXGBE_FLAG_NEED_LINK_CONFIG;
> +		if (ixgbe_get_media_type(hw) == ixgbe_media_type_fiber) {
> +			intr->flags |= IXGBE_FLAG_NEED_LINK_CONFIG;
> +			rte_eal_alarm_set(10,
> +				ixgbe_dev_setup_link_alarm_handler, dev);
> +		}
>  		return rte_eth_linkstatus_set(dev, &link);
>  	}
> 
> -	intr->flags &= ~IXGBE_FLAG_NEED_LINK_CONFIG;
>  	link.link_status = ETH_LINK_UP;
>  	link.link_duplex = ETH_LINK_FULL_DUPLEX;
> 
> @@ -5128,6 +5147,8 @@ ixgbevf_dev_stop(struct rte_eth_dev *dev)
> 
>  	PMD_INIT_FUNC_TRACE();
> 
> +	rte_eal_alarm_cancel(ixgbe_dev_setup_link_alarm_handler, dev);
> +
>  	ixgbevf_intr_disable(dev);
> 
>  	hw->adapter_stopped = 1;
> --
> 2.17.1