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ice: xsk: Avoid potential dead AF_XDP Tx processing
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Commit 9610bd9 ("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: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Alexander Lobakin <alexandr.lobakin@intel.com>
Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>
Link: https://lore.kernel.org/bpf/20220125160446.78976-7-maciej.fijalkowski@intel.com
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Maciej Fijalkowski authored and Daniel Borkmann committed Jan 27, 2022
1 parent d1bc532 commit 86e3f78
Showing 1 changed file with 2 additions and 0 deletions.
2 changes: 2 additions & 0 deletions drivers/net/ethernet/intel/ice/ice_txrx.c
Original file line number Diff line number Diff line change
Expand Up @@ -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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