Re: [PATCH V2 net 07/20] net/ena: refactor ena_get_stats64 to be atomic context safe

[Netanel Belgazal]

On 12/05/2016 06:24 AM, Matt Wilson wrote:
> On Sun, Dec 04, 2016 at 03:19:25PM +0200, Netanel Belgazal wrote:
> > ndo_get_stat64 can be called from atomic context.
> > However the current implementation sends an admin command to retrieve
> > the statistics from the device.
> > This admin commands uses sleep.
> Suggest some comment edits:
>
> ndo_get_stat64() can be called from atomic context, but the current
> implementation sends an admin command to retrieve the statistics from
> the device. This admin command can sleep.
>
> > Refactor the implementation of ena_get_stats64 to take the
> > {rx,tx}bytes/cnt from the driver's inner counters
> > and to take the rx drops counter
> > from the asynchronous keep alive (heart bit) event.
> This patch re-factors the implementation of ena_get_stats64() to use
> the {rx,tx}bytes/count from the driver's inner counters, and to obtain
> the rx drop counter from the asynchronous keep alive (heart bit)
> event.
Applied
> --msw
>
> > Signed-off-by: Netanel Belgazal <netanel@xxxxxxxxxxxxxxxxx>
> > ---
> >   drivers/net/ethernet/amazon/ena/ena_admin_defs.h |  8 ++++
> >   drivers/net/ethernet/amazon/ena/ena_netdev.c     | 57 +++++++++++++++++-------
> >   drivers/net/ethernet/amazon/ena/ena_netdev.h     |  1 +
> >   3 files changed, 51 insertions(+), 15 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/amazon/ena/ena_admin_defs.h b/drivers/net/ethernet/amazon/ena/ena_admin_defs.h
> > index f48c886..6d70bf5 100644
> > --- a/drivers/net/ethernet/amazon/ena/ena_admin_defs.h
> > +++ b/drivers/net/ethernet/amazon/ena/ena_admin_defs.h
> > @@ -873,6 +873,14 @@ struct ena_admin_aenq_link_change_desc {
> >   	u32 flags;
> >   };
> >   
> > +struct ena_admin_aenq_keep_alive_desc {
> > +	struct ena_admin_aenq_common_desc aenq_common_desc;
> > +
> > +	u32 rx_drops_low;
> > +
> > +	u32 rx_drops_high;
> > +};
> > +
> >   struct ena_admin_ena_mmio_req_read_less_resp {
> >   	u16 req_id;
> >   
> > diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.c b/drivers/net/ethernet/amazon/ena/ena_netdev.c
> > index ad5f78f..962ffb5 100644
> > --- a/drivers/net/ethernet/amazon/ena/ena_netdev.c
> > +++ b/drivers/net/ethernet/amazon/ena/ena_netdev.c
> > @@ -2176,28 +2176,46 @@ static struct rtnl_link_stats64 *ena_get_stats64(struct net_device *netdev,
> >   						 struct rtnl_link_stats64 *stats)
> >   {
> >   	struct ena_adapter *adapter = netdev_priv(netdev);
> > -	struct ena_admin_basic_stats ena_stats;
> > -	int rc;
> > +	struct ena_ring *rx_ring, *tx_ring;
> > +	unsigned int start;
> > +	u64 rx_drops;
> > +	int i;
> >   
> >   	if (!test_bit(ENA_FLAG_DEV_UP, &adapter->flags))
> >   		return NULL;
> >   
> > -	rc = ena_com_get_dev_basic_stats(adapter->ena_dev, &ena_stats);
> > -	if (rc)
> > -		return NULL;
> > +	for (i = 0; i < adapter->num_queues; i++) {
> > +		u64 bytes, packets;
> > +
> > +		tx_ring = &adapter->tx_ring[i];
> > +
> > +		do {
> > +			start = u64_stats_fetch_begin_irq(&tx_ring->syncp);
> > +			packets = tx_ring->tx_stats.cnt;
> > +			bytes = tx_ring->tx_stats.bytes;
> > +		} while (u64_stats_fetch_retry_irq(&tx_ring->syncp, start));
> > +
> > +		stats->tx_packets += packets;
> > +		stats->tx_bytes += bytes;
> >   
> > -	stats->tx_bytes = ((u64)ena_stats.tx_bytes_high << 32) |
> > -		ena_stats.tx_bytes_low;
> > -	stats->rx_bytes = ((u64)ena_stats.rx_bytes_high << 32) |
> > -		ena_stats.rx_bytes_low;
> > +		rx_ring = &adapter->rx_ring[i];
> > +
> > +		do {
> > +			start = u64_stats_fetch_begin_irq(&rx_ring->syncp);
> > +			packets = rx_ring->rx_stats.cnt;
> > +			bytes = rx_ring->rx_stats.bytes;
> > +		} while (u64_stats_fetch_retry_irq(&rx_ring->syncp, start));
> >   
> > -	stats->rx_packets = ((u64)ena_stats.rx_pkts_high << 32) |
> > -		ena_stats.rx_pkts_low;
> > -	stats->tx_packets = ((u64)ena_stats.tx_pkts_high << 32) |
> > -		ena_stats.tx_pkts_low;
> > +		stats->rx_packets += packets;
> > +		stats->rx_bytes += bytes;
> > +	}
> > +
> > +	do {
> > +		start = u64_stats_fetch_begin_irq(&adapter->syncp);
> > +		rx_drops = adapter->dev_stats.rx_drops;
> > +	} while (u64_stats_fetch_retry_irq(&adapter->syncp, start));
> >   
> > -	stats->rx_dropped = ((u64)ena_stats.rx_drops_high << 32) |
> > -		ena_stats.rx_drops_low;
> > +	stats->rx_dropped = rx_drops;
> >   
> >   	stats->multicast = 0;
> >   	stats->collisions = 0;
> > @@ -3221,8 +3239,17 @@ static void ena_keep_alive_wd(void *adapter_data,
> >   			      struct ena_admin_aenq_entry *aenq_e)
> >   {
> >   	struct ena_adapter *adapter = (struct ena_adapter *)adapter_data;
> > +	struct ena_admin_aenq_keep_alive_desc *desc;
> > +	u64 rx_drops;
> >   
> > +	desc = (struct ena_admin_aenq_keep_alive_desc *)aenq_e;
> >   	adapter->last_keep_alive_jiffies = jiffies;
> > +
> > +	rx_drops = ((u64)desc->rx_drops_high << 32) | desc->rx_drops_low;
> > +
> > +	u64_stats_update_begin(&adapter->syncp);
> > +	adapter->dev_stats.rx_drops = rx_drops;
> > +	u64_stats_update_end(&adapter->syncp);
> >   }
> >   
> >   static void ena_notification(void *adapter_data,
> > diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.h b/drivers/net/ethernet/amazon/ena/ena_netdev.h
> > index 69d7e9e..f0ddc11 100644
> > --- a/drivers/net/ethernet/amazon/ena/ena_netdev.h
> > +++ b/drivers/net/ethernet/amazon/ena/ena_netdev.h
> > @@ -241,6 +241,7 @@ struct ena_stats_dev {
> >   	u64 interface_up;
> >   	u64 interface_down;
> >   	u64 admin_q_pause;
> > +	u64 rx_drops;
> >   };
> >   
> >   enum ena_flags_t {