diff mbox series

[v2,iwl-net,1/8] ice: respect netif readiness in AF_XDP ZC related ndo's

Message ID 20240529112337.3639084-2-maciej.fijalkowski@intel.com (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series ice: fix AF_XDP ZC timeout and concurrency issues | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for net
netdev/apply fail Patch does not apply to net-0

Commit Message

Maciej Fijalkowski May 29, 2024, 11:23 a.m. UTC 
From: Michal Kubiak <michal.kubiak@intel.com>

Address a scenario in which XSK ZC Tx produces descriptors to XDP Tx
ring when link is either not yet fully initialized or process of
stopping the netdev has already started. To avoid this, add checks
against carrier readiness in ice_xsk_wakeup() and in ice_xmit_zc().
One could argue that bailing out early in ice_xsk_wakeup() would be
sufficient but given the fact that we produce Tx descriptors on behalf
of NAPI that is triggered for Rx traffic, the latter is also needed.

Bringing link up is an asynchronous event executed within
ice_service_task so even though interface has been brought up there is
still a time frame where link is not yet ok.

Without this patch, when AF_XDP ZC Tx is used simultaneously with stack
Tx, Tx timeouts occur after going through link flap (admin brings
interface down then up again). HW seem to be unable to transmit
descriptor to the wire after HW tail register bump which in turn causes
bit __QUEUE_STATE_STACK_XOFF to be set forever as
netdev_tx_completed_queue() sees no cleaned bytes on the input.

Fixes: 126cdfe1007a ("ice: xsk: Improve AF_XDP ZC Tx and use batching API")
Fixes: 2d4238f55697 ("ice: Add support for AF_XDP")
Signed-off-by: Michal Kubiak <michal.kubiak@intel.com>
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
---
 drivers/net/ethernet/intel/ice/ice_xsk.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

Comments

Rout, ChandanX June 4, 2024, 6:47 a.m. UTC | #1 
>-----Original Message-----
>From: Intel-wired-lan <intel-wired-lan-bounces@osuosl.org> On Behalf Of
>Fijalkowski, Maciej
>Sent: Wednesday, May 29, 2024 4:54 PM
>To: intel-wired-lan@lists.osuosl.org
>Cc: Fijalkowski, Maciej <maciej.fijalkowski@intel.com>; Zaremba, Larysa
><larysa.zaremba@intel.com>; netdev@vger.kernel.org; Kubiak, Michal
><michal.kubiak@intel.com>; Nguyen, Anthony L
><anthony.l.nguyen@intel.com>; Karlsson, Magnus
><magnus.karlsson@intel.com>
>Subject: [Intel-wired-lan] [PATCH v2 iwl-net 1/8] ice: respect netif readiness in
>AF_XDP ZC related ndo's
>
>From: Michal Kubiak <michal.kubiak@intel.com>
>
>Address a scenario in which XSK ZC Tx produces descriptors to XDP Tx ring
>when link is either not yet fully initialized or process of stopping the netdev has
>already started. To avoid this, add checks against carrier readiness in
>ice_xsk_wakeup() and in ice_xmit_zc().
>One could argue that bailing out early in ice_xsk_wakeup() would be sufficient
>but given the fact that we produce Tx descriptors on behalf of NAPI that is
>triggered for Rx traffic, the latter is also needed.
>
>Bringing link up is an asynchronous event executed within ice_service_task so
>even though interface has been brought up there is still a time frame where link
>is not yet ok.
>
>Without this patch, when AF_XDP ZC Tx is used simultaneously with stack Tx, Tx
>timeouts occur after going through link flap (admin brings interface down then
>up again). HW seem to be unable to transmit descriptor to the wire after HW
>tail register bump which in turn causes bit __QUEUE_STATE_STACK_XOFF to be
>set forever as
>netdev_tx_completed_queue() sees no cleaned bytes on the input.
>
>Fixes: 126cdfe1007a ("ice: xsk: Improve AF_XDP ZC Tx and use batching API")
>Fixes: 2d4238f55697 ("ice: Add support for AF_XDP")
>Signed-off-by: Michal Kubiak <michal.kubiak@intel.com>
>Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
>---
> drivers/net/ethernet/intel/ice/ice_xsk.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>

Tested-by: Chandan Kumar Rout <chandanx.rout@intel.com> (A Contingent Worker at Intel)
diff mbox series

Patch

diff --git a/drivers/net/ethernet/intel/ice/ice_xsk.c b/drivers/net/ethernet/intel/ice/ice_xsk.c
index 2015f66b0cf9..1bd4b054dd80 100644
--- a/drivers/net/ethernet/intel/ice/ice_xsk.c
+++ b/drivers/net/ethernet/intel/ice/ice_xsk.c
@@ -1048,6 +1048,10 @@  bool ice_xmit_zc(struct ice_tx_ring *xdp_ring)
 
 	ice_clean_xdp_irq_zc(xdp_ring);
 
+	if (!netif_carrier_ok(xdp_ring->vsi->netdev) ||
+	    !netif_running(xdp_ring->vsi->netdev))
+		return true;
+
 	budget = ICE_DESC_UNUSED(xdp_ring);
 	budget = min_t(u16, budget, ICE_RING_QUARTER(xdp_ring));
 
@@ -1091,7 +1095,7 @@  ice_xsk_wakeup(struct net_device *netdev, u32 queue_id,
 	struct ice_vsi *vsi = np->vsi;
 	struct ice_tx_ring *ring;
 
-	if (test_bit(ICE_VSI_DOWN, vsi->state))
+	if (test_bit(ICE_VSI_DOWN, vsi->state) || !netif_carrier_ok(netdev))
 		return -ENETDOWN;
 
 	if (!ice_is_xdp_ena_vsi(vsi))