Re: [PATCH v3 09/15] net/sfc: use new rte_eth_linkstatus functions

[Stephen Hemminger <stephen@networkplumber.org>]

On Tue, 9 Jan 2018 13:35:58 +0300
Andrew Rybchenko <arybchenko@solarflare.com> wrote:

> On 01/08/2018 08:45 PM, Stephen Hemminger wrote:
> > Use the new API (_rte_eth_linkstatus_set) to handle link status update.
> >
> > Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> > ---
> >   drivers/net/sfc/sfc_ethdev.c | 27 +++++++--------------------
> >   drivers/net/sfc/sfc_ev.c     | 23 ++++-------------------
> >   2 files changed, 11 insertions(+), 39 deletions(-)
> >
> > diff --git a/drivers/net/sfc/sfc_ethdev.c b/drivers/net/sfc/sfc_ethdev.c
> > index 2f5f86f84877..e0a12b32b1a3 100644
> > --- a/drivers/net/sfc/sfc_ethdev.c
> > +++ b/drivers/net/sfc/sfc_ethdev.c
> > @@ -238,22 +238,12 @@ static int
> >   sfc_dev_link_update(struct rte_eth_dev *dev, int wait_to_complete)
> >   {
> >   	struct sfc_adapter *sa = dev->data->dev_private;
> > -	struct rte_eth_link *dev_link = &dev->data->dev_link;
> > -	struct rte_eth_link old_link;
> >   	struct rte_eth_link current_link;
> >   
> >   	sfc_log_init(sa, "entry");
> >   
> > -retry:
> > -	EFX_STATIC_ASSERT(sizeof(*dev_link) == sizeof(rte_atomic64_t));
> > -	*(int64_t *)&old_link = rte_atomic64_read((rte_atomic64_t *)dev_link);
> > -
> >   	if (sa->state != SFC_ADAPTER_STARTED) {
> >   		sfc_port_link_mode_to_info(EFX_LINK_UNKNOWN, &current_link);
> > -		if (!rte_atomic64_cmpset((volatile uint64_t *)dev_link,
> > -					 *(uint64_t *)&old_link,
> > -					 *(uint64_t *)&current_link))
> > -			goto retry;
> >   	} else if (wait_to_complete) {
> >   		efx_link_mode_t link_mode;
> >   
> > @@ -261,21 +251,18 @@ sfc_dev_link_update(struct rte_eth_dev *dev, int wait_to_complete)
> >   			link_mode = EFX_LINK_UNKNOWN;
> >   		sfc_port_link_mode_to_info(link_mode, &current_link);
> >   
> > -		if (!rte_atomic64_cmpset((volatile uint64_t *)dev_link,
> > -					 *(uint64_t *)&old_link,
> > -					 *(uint64_t *)&current_link))
> > -			goto retry;
> >   	} else {
> >   		sfc_ev_mgmt_qpoll(sa);
> > -		*(int64_t *)&current_link =
> > -			rte_atomic64_read((rte_atomic64_t *)dev_link);
> > +		_rte_eth_linkstatus_get(dev, &current_link);
> >   	}
> >   
> > -	if (old_link.link_status != current_link.link_status)
> > -		sfc_info(sa, "Link status is %s",
> > -			 current_link.link_status ? "UP" : "DOWN");
> > +	if (_rte_eth_linkstatus_set(dev, &current_link) == 0)
> > +		return 0;
> > +
> > +	sfc_info(sa, "Link status is %s",
> > +		 current_link.link_status ? "UP" : "DOWN");
> >   
> > -	return old_link.link_status == current_link.link_status ? 0 : -1;
> > +	return -1;
> >   }
> >   
> >   static void
> > diff --git a/drivers/net/sfc/sfc_ev.c b/drivers/net/sfc/sfc_ev.c
> > index a16dc27b380e..3e96536a9d60 100644
> > --- a/drivers/net/sfc/sfc_ev.c
> > +++ b/drivers/net/sfc/sfc_ev.c
> > @@ -404,29 +404,14 @@ sfc_ev_link_change(void *arg, efx_link_mode_t link_mode)
> >   {
> >   	struct sfc_evq *evq = arg;
> >   	struct sfc_adapter *sa = evq->sa;
> > -	struct rte_eth_link *dev_link = &sa->eth_dev->data->dev_link;
> >   	struct rte_eth_link new_link;
> > -	uint64_t new_link_u64;
> > -	uint64_t old_link_u64;
> > -
> > -	EFX_STATIC_ASSERT(sizeof(*dev_link) == sizeof(rte_atomic64_t));
> >   
> >   	sfc_port_link_mode_to_info(link_mode, &new_link);
> > +	if (_rte_eth_linkstatus_set(sa->eth_dev, &new_link) == 0)
> > +		return B_FALSE;
> >   
> > -	new_link_u64 = *(uint64_t *)&new_link;
> > -	do {
> > -		old_link_u64 = rte_atomic64_read((rte_atomic64_t *)dev_link);
> > -		if (old_link_u64 == new_link_u64)
> > -			break;
> > -
> > -		if (rte_atomic64_cmpset((volatile uint64_t *)dev_link,
> > -					old_link_u64, new_link_u64)) {
> > -			evq->sa->port.lsc_seq++;
> > -			break;
> > -		}
> > -	} while (B_TRUE);
> > -
> > -	return B_FALSE;
> > +	evq->sa->port.lsc_seq++;
> > +	return B_TRUE;  
> 
> It still returns B_TRUE, but should return B_FALSE as before.
> Also before the patch lsc_seq is incremented in the case of any
> changes in link status, but now in the case of up/down change only.

The old code looked broken and did not match the comments.
It always returned B_FALSE independent of whether link status changed
or not.