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

[Netanel Belgazal <netanel@annapurnalabs.com>]

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@annapurnalabs.com>
>> ---
>>   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 {