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Message-ID: <87wmgfvua8.fsf@intel.com>
Date: Wed, 04 Dec 2024 16:38:07 -0800
From: Vinicius Costa Gomes <vinicius.gomes@...el.com>
To: Song Yoong Siang <yoong.siang.song@...el.com>, Alexei Starovoitov
<ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, "David S .
Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, Jesper
Dangaard Brouer <hawk@...nel.org>, John Fastabend
<john.fastabend@...il.com>, Tony Nguyen <anthony.l.nguyen@...el.com>,
Przemek Kitszel <przemyslaw.kitszel@...el.com>, Andrew Lunn
<andrew+netdev@...n.ch>, Eric Dumazet <edumazet@...gle.com>, Paolo Abeni
<pabeni@...hat.com>, Richard Cochran <richardcochran@...il.com>
Cc: intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org, bpf@...r.kernel.org
Subject: Re: [PATCH iwl-next 1/1] igc: Improve XDP_SETUP_PROG process
Song Yoong Siang <yoong.siang.song@...el.com> writes:
> Improve XDP_SETUP_PROG process by avoiding unnecessary link down/up event
> and hardware device reset.
>
Some examples of problems that these hardware resets are causing would
be good.
> Signed-off-by: Song Yoong Siang <yoong.siang.song@...el.com>
> ---
The duplication of code doesn't look that good. Initialization is
tricky, it seems to make it easy to update one place and forget to
update the other.
A couple of ideas:
- separate the code into functions that can be used from the "usual"
igc_open()/igc_close() flow;
- it seems that igc_close()/igc_open() are too big a hammer for
installing a new XDP program: what do we really need? (my mental model
is: 1. stop new traffic from going into any queue; 2. wait for any
packets "in progress"; 3. install the program; 4. resume operations;
what else?)
> drivers/net/ethernet/intel/igc/igc.h | 2 +
> drivers/net/ethernet/intel/igc/igc_main.c | 138 ++++++++++++++++++++++
> drivers/net/ethernet/intel/igc/igc_xdp.c | 4 +-
> 3 files changed, 142 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/igc/igc.h b/drivers/net/ethernet/intel/igc/igc.h
> index eac0f966e0e4..b1e46fcaae1a 100644
> --- a/drivers/net/ethernet/intel/igc/igc.h
> +++ b/drivers/net/ethernet/intel/igc/igc.h
> @@ -341,6 +341,8 @@ void igc_up(struct igc_adapter *adapter);
> void igc_down(struct igc_adapter *adapter);
> int igc_open(struct net_device *netdev);
> int igc_close(struct net_device *netdev);
> +void igc_xdp_open(struct net_device *netdev);
> +void igc_xdp_close(struct net_device *netdev);
> int igc_setup_tx_resources(struct igc_ring *ring);
> int igc_setup_rx_resources(struct igc_ring *ring);
> void igc_free_tx_resources(struct igc_ring *ring);
> diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
> index 27872bdea9bd..098529a80b88 100644
> --- a/drivers/net/ethernet/intel/igc/igc_main.c
> +++ b/drivers/net/ethernet/intel/igc/igc_main.c
> @@ -6145,6 +6145,144 @@ int igc_close(struct net_device *netdev)
> return 0;
> }
>
> +void igc_xdp_open(struct net_device *netdev)
> +{
> + struct igc_adapter *adapter = netdev_priv(netdev);
> + struct pci_dev *pdev = adapter->pdev;
> + struct igc_hw *hw = &adapter->hw;
> + int err = 0;
> + int i = 0;
> +
> + /* disallow open during test */
> + if (test_bit(__IGC_TESTING, &adapter->state))
> + return;
> +
> + pm_runtime_get_sync(&pdev->dev);
> +
> + igc_ptp_reset(adapter);
> +
> + /* allocate transmit descriptors */
> + err = igc_setup_all_tx_resources(adapter);
> + if (err)
> + goto err_setup_tx;
> +
> + /* allocate receive descriptors */
> + err = igc_setup_all_rx_resources(adapter);
> + if (err)
> + goto err_setup_rx;
> +
> + igc_setup_tctl(adapter);
> + igc_setup_rctl(adapter);
> + igc_configure_tx(adapter);
> + igc_configure_rx(adapter);
> + igc_rx_fifo_flush_base(&adapter->hw);
> +
> + /* call igc_desc_unused which always leaves
> + * at least 1 descriptor unused to make sure
> + * next_to_use != next_to_clean
> + */
> + for (i = 0; i < adapter->num_rx_queues; i++) {
> + struct igc_ring *ring = adapter->rx_ring[i];
> +
> + if (ring->xsk_pool)
> + igc_alloc_rx_buffers_zc(ring, igc_desc_unused(ring));
> + else
> + igc_alloc_rx_buffers(ring, igc_desc_unused(ring));
> + }
> +
> + err = igc_request_irq(adapter);
> + if (err)
> + goto err_req_irq;
> +
> + clear_bit(__IGC_DOWN, &adapter->state);
> +
> + for (i = 0; i < adapter->num_q_vectors; i++)
> + napi_enable(&adapter->q_vector[i]->napi);
> +
> + /* Clear any pending interrupts. */
> + rd32(IGC_ICR);
> + igc_irq_enable(adapter);
> +
> + pm_runtime_put(&pdev->dev);
> +
> + netif_tx_start_all_queues(netdev);
> + netif_carrier_on(netdev);
> +
> + return;
> +
> +err_req_irq:
> + igc_release_hw_control(adapter);
> + igc_power_down_phy_copper_base(&adapter->hw);
> + igc_free_all_rx_resources(adapter);
> +err_setup_rx:
> + igc_free_all_tx_resources(adapter);
> +err_setup_tx:
> + igc_reset(adapter);
> + pm_runtime_put(&pdev->dev);
> +}
> +
> +void igc_xdp_close(struct net_device *netdev)
> +{
> + struct igc_adapter *adapter = netdev_priv(netdev);
> + struct pci_dev *pdev = adapter->pdev;
> + struct igc_hw *hw = &adapter->hw;
> + u32 tctl, rctl;
> + int i = 0;
> +
> + WARN_ON(test_bit(__IGC_RESETTING, &adapter->state));
> +
> + pm_runtime_get_sync(&pdev->dev);
> +
> + set_bit(__IGC_DOWN, &adapter->state);
> +
> + igc_ptp_suspend(adapter);
> +
> + if (pci_device_is_present(pdev)) {
> + /* disable receives in the hardware */
> + rctl = rd32(IGC_RCTL);
> + wr32(IGC_RCTL, rctl & ~IGC_RCTL_EN);
> + /* flush and sleep below */
> + }
> + /* set trans_start so we don't get spurious watchdogs during reset */
> + netif_trans_update(netdev);
> +
> + netif_carrier_off(netdev);
> + netif_tx_stop_all_queues(netdev);
> +
> + if (pci_device_is_present(pdev)) {
> + /* disable transmits in the hardware */
> + tctl = rd32(IGC_TCTL);
> + tctl &= ~IGC_TCTL_EN;
> + wr32(IGC_TCTL, tctl);
> + /* flush both disables and wait for them to finish */
> + wrfl();
> + usleep_range(10000, 20000);
> +
> + igc_irq_disable(adapter);
> + }
> +
> + for (i = 0; i < adapter->num_q_vectors; i++) {
> + if (adapter->q_vector[i]) {
> + napi_synchronize(&adapter->q_vector[i]->napi);
> + napi_disable(&adapter->q_vector[i]->napi);
> + }
> + }
> +
> + del_timer_sync(&adapter->watchdog_timer);
> + del_timer_sync(&adapter->phy_info_timer);
> +
> + igc_disable_all_tx_rings_hw(adapter);
> + igc_clean_all_tx_rings(adapter);
> + igc_clean_all_rx_rings(adapter);
> +
> + igc_free_irq(adapter);
> +
> + igc_free_all_tx_resources(adapter);
> + igc_free_all_rx_resources(adapter);
> +
> + pm_runtime_put_sync(&pdev->dev);
> +}
> +
> /**
> * igc_ioctl - Access the hwtstamp interface
> * @netdev: network interface device structure
> diff --git a/drivers/net/ethernet/intel/igc/igc_xdp.c b/drivers/net/ethernet/intel/igc/igc_xdp.c
> index 869815f48ac1..f1d6ab56ab54 100644
> --- a/drivers/net/ethernet/intel/igc/igc_xdp.c
> +++ b/drivers/net/ethernet/intel/igc/igc_xdp.c
> @@ -25,7 +25,7 @@ int igc_xdp_set_prog(struct igc_adapter *adapter, struct bpf_prog *prog,
>
> need_update = !!adapter->xdp_prog != !!prog;
> if (if_running && need_update)
> - igc_close(dev);
> + igc_xdp_close(dev);
>
> old_prog = xchg(&adapter->xdp_prog, prog);
> if (old_prog)
> @@ -37,7 +37,7 @@ int igc_xdp_set_prog(struct igc_adapter *adapter, struct bpf_prog *prog,
> xdp_features_clear_redirect_target(dev);
>
> if (if_running && need_update)
> - igc_open(dev);
> + igc_xdp_open(dev);
>
> return 0;
> }
> --
> 2.34.1
>
>
Cheers,
--
Vinicius
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