[dpdk-dev] [PATCH v5 02/15] ethdev: add linkstatus get/set helper functions

[Andrew Rybchenko]

On 01/16/2018 09:37 PM, Stephen Hemminger wrote:
> Many drivers are all doing copy/paste of the same code to atomically
> update the link status. Reduce duplication, and allow for future
> changes by having common function for this.
>
> Signed-off-by: Stephen Hemminger <stephen at networkplumber.org>
> ---
>   lib/librte_ether/rte_ethdev.c | 22 +++------------
>   lib/librte_ether/rte_ethdev.h | 62 +++++++++++++++++++++++++++++++++++++++++++
>   2 files changed, 66 insertions(+), 18 deletions(-)
>
> diff --git a/lib/librte_ether/rte_ethdev.c b/lib/librte_ether/rte_ethdev.c
> index a524af740f4a..d6433af35a19 100644
> --- a/lib/librte_ether/rte_ethdev.c
> +++ b/lib/librte_ether/rte_ethdev.c
> @@ -1447,20 +1447,6 @@ rte_eth_allmulticast_get(uint16_t port_id)
>   	return dev->data->all_multicast;
>   }
>   
> -static inline int
> -rte_eth_dev_atomic_read_link_status(struct rte_eth_dev *dev,
> -				struct rte_eth_link *link)
> -{
> -	struct rte_eth_link *dst = link;
> -	struct rte_eth_link *src = &(dev->data->dev_link);
> -
> -	if (rte_atomic64_cmpset((uint64_t *)dst, *(uint64_t *)dst,
> -					*(uint64_t *)src) == 0)
> -		return -1;
> -
> -	return 0;
> -}
> -
>   void
>   rte_eth_link_get(uint16_t port_id, struct rte_eth_link *eth_link)
>   {
> @@ -1469,8 +1455,8 @@ rte_eth_link_get(uint16_t port_id, struct rte_eth_link *eth_link)
>   	RTE_ETH_VALID_PORTID_OR_RET(port_id);
>   	dev = &rte_eth_devices[port_id];
>   
> -	if (dev->data->dev_conf.intr_conf.lsc != 0)
> -		rte_eth_dev_atomic_read_link_status(dev, eth_link);
> +	if (dev->data->dev_conf.intr_conf.lsc)
> +		rte_eth_linkstatus_get(dev, eth_link);
>   	else {
>   		RTE_FUNC_PTR_OR_RET(*dev->dev_ops->link_update);
>   		(*dev->dev_ops->link_update)(dev, 1);
> @@ -1486,8 +1472,8 @@ rte_eth_link_get_nowait(uint16_t port_id, struct rte_eth_link *eth_link)
>   	RTE_ETH_VALID_PORTID_OR_RET(port_id);
>   	dev = &rte_eth_devices[port_id];
>   
> -	if (dev->data->dev_conf.intr_conf.lsc != 0)
> -		rte_eth_dev_atomic_read_link_status(dev, eth_link);
> +	if (dev->data->dev_conf.intr_conf.lsc)
> +		rte_eth_linkstatus_get(dev, eth_link);
>   	else {
>   		RTE_FUNC_PTR_OR_RET(*dev->dev_ops->link_update);
>   		(*dev->dev_ops->link_update)(dev, 0);
> diff --git a/lib/librte_ether/rte_ethdev.h b/lib/librte_ether/rte_ethdev.h
> index b10e2a92da71..ec8255656967 100644
> --- a/lib/librte_ether/rte_ethdev.h
> +++ b/lib/librte_ether/rte_ethdev.h
> @@ -2218,6 +2218,68 @@ int rte_eth_dev_set_link_down(uint16_t port_id);
>    */
>   void rte_eth_dev_close(uint16_t port_id);
>   
> +
> +/**
> + * @internal
> + * Atomically set the link status for the specific device.
> + * It is for use by DPDK device driver use only.
> + * User applications should not call it
> + *
> + * @param dev
> + *  Pointer to struct rte_eth_dev.
> + * @param link
> + *  New link status value.
> + * @return
> + *  1 if link status has changed;
> + *  0 if link status is unchanged.

Here "link status" is used as up/down status of the link.

> + */
> +static inline int
> +rte_eth_linkstatus_set(struct rte_eth_dev *dev,
> +		       const struct rte_eth_link *new_link)

Here (and function and the second parameter description) "link status"
is used as all information about link.
rte_ethdev API calls it just "link" (link_update, link_get_wait/nowait).
It is not a big problem, but it is better to avoid it.

Thanks.

> +{
> +	volatile uint64_t *dev_link
> +		 = (volatile uint64_t *)&(dev->data->dev_link);
> +	union {
> +		uint64_t val64;
> +		struct rte_eth_link link;
> +	} orig;
> +
> +	RTE_BUILD_BUG_ON(sizeof(*new_link) != sizeof(uint64_t));
> +
> +	orig.val64 = rte_atomic64_exchange(dev_link,
> +					   *(const uint64_t *)new_link);
> +
> +	return orig.link.link_status != new_link->link_status;
> +}
> +
> +/**
> + * @internal
> + * Atomically get the link speed and status.
> + *
> + * @param dev
> + *  Pointer to struct rte_eth_dev.
> + * @param link
> + *  link status value.
> + */
> +static inline void
> +rte_eth_linkstatus_get(const struct rte_eth_dev *dev,
> +		       struct rte_eth_link *link)
> +{
> +	volatile uint64_t *src = (uint64_t *)&(dev->data->dev_link);
> +	uint64_t *dst = (uint64_t *)link;
> +
> +	RTE_BUILD_BUG_ON(sizeof(*link) != sizeof(uint64_t));
> +
> +	/* can't use rte_atomic64_read because it returns signed int */
> +#ifdef __LP64__
> +	*dst = *src;
> +#else
> +	do {
> +		*dst = *src;
> +	} while (!rte_atomic64_cmpset(src, *dst, *dst));
> +#endif
> +}
> +
>   /**
>    * Reset a Ethernet device and keep its port id.
>    *