Commit 86e3f78c authored by Maciej Fijalkowski's avatar Maciej Fijalkowski Committed by Daniel Borkmann

ice: xsk: Avoid potential dead AF_XDP Tx processing

Commit 9610bd98 ("ice: optimize XDP_TX workloads") introduced
@next_dd and @next_rs to ice_tx_ring struct. Currently, their state is
not restored in ice_clean_tx_ring(), which was not causing any troubles
as the XDP rings are gone after we're done with XDP prog on interface.

For upcoming usage of mentioned fields in AF_XDP, this might expose us
to a potential dead Tx side. Scenario would look like following (based
on xdpsock):

- two xdpsock instances are spawned in Tx mode
- one of them is killed
- XDP prog is kept on interface due to the other xdpsock still running
  * this means that XDP rings stayed in place
- xdpsock is launched again on same queue id that was terminated on
- @next_dd and @next_rs setting is bogus, therefore transmit side is
  broken

To protect us from the above, restore the initial @next_rs and @next_dd
values when cleaning the Tx ring.
Signed-off-by: default avatarMaciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Reviewed-by: default avatarAlexander Lobakin <alexandr.lobakin@intel.com>
Acked-by: default avatarMagnus Karlsson <magnus.karlsson@intel.com>
Link: https://lore.kernel.org/bpf/20220125160446.78976-7-maciej.fijalkowski@intel.com
parent d1bc532e
......@@ -173,6 +173,8 @@ void ice_clean_tx_ring(struct ice_tx_ring *tx_ring)
tx_ring->next_to_use = 0;
tx_ring->next_to_clean = 0;
tx_ring->next_dd = ICE_RING_QUARTER(tx_ring) - 1;
tx_ring->next_rs = ICE_RING_QUARTER(tx_ring) - 1;
if (!tx_ring->netdev)
return;
......
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