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Date: Sun, 4 Dec 2016 20:24:35 -0800
From: Matt Wilson <msw@...n.com>
To: Netanel Belgazal <netanel@...apurnalabs.com>
CC: <linux-kernel@...r.kernel.org>, <davem@...emloft.net>,
<netdev@...r.kernel.org>, <dwmw@...zon.com>,
<zorik@...apurnalabs.com>, <alex@...apurnalabs.com>,
<saeed@...apurnalabs.com>, <msw@...zon.com>, <aliguori@...zon.com>,
<nafea@...apurnalabs.com>
Subject: Re: [PATCH V2 net 07/20] net/ena: refactor ena_get_stats64 to be
atomic context safe
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.
--msw
> Signed-off-by: Netanel Belgazal <netanel@...apurnalabs.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 {
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