Re: [PATCH bpf-next v2 2/4] ice: xsk: avoid potential dead AF_XDP Tx processing
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From: Magnus Karlsson <hidden>
Date: 2021-12-21 07:38:15
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bpf
On Fri, Dec 17, 2021 at 12:38 AM Maciej Fijalkowski [off-list ref] wrote:
Commit 9610bd988df9 ("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 default @next_rs and @next_dd
values when cleaning the Tx ring.Thank you Maciej. Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>
quoted hunk ↗ jump to hunk
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com> --- drivers/net/ethernet/intel/ice/ice_txrx.c | 2 ++ 1 file changed, 2 insertions(+)diff --git a/drivers/net/ethernet/intel/ice/ice_txrx.c b/drivers/net/ethernet/intel/ice/ice_txrx.c index bc3ba19dc88f..0f3f92ce8a95 100644 --- a/drivers/net/ethernet/intel/ice/ice_txrx.c +++ b/drivers/net/ethernet/intel/ice/ice_txrx.c@@ -172,6 +172,8 @@ 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_TX_THRESH - 1; + tx_ring->next_rs = ICE_TX_THRESH - 1; if (!tx_ring->netdev) return; --2.33.1