> When generic_xdp_tx() fails to transmit an skb, it reports the drop
> through trace_xdp_exception() with the action hardcoded to XDP_TX.
> That was right when generic XDP was added, and XDP_TX was the only
> caller. Since then, two XDP_REDIRECT paths have started to transmit
> through generic_xdp_tx() as well:
>
> - xdp_do_generic_redirect(), for a redirect to an ifindex
> - dev_map_generic_redirect(), for DEVMAP and DEVMAP_HASH redirects,
> including broadcast
>
> Drops on those paths are reported as XDP_TX, an action which the
> program never returned. Tools which count xdp:xdp_exception events per
> action, such as the samples/bpf programs built on xdp_sample, therefore
> attribute generic XDP redirect drops to the wrong action. Drivers with
> native XDP already report XDP_TX and XDP_REDIRECT drops separately.
>
> Add an "act" argument to generic_xdp_tx(), and have each caller pass
> the action that led to the transmission: XDP_TX from do_xdp_generic(),
> XDP_REDIRECT from the two redirect paths. generic_xdp_tx() is not
> exported, so these are all of its users.
>
> Fixes: 6103aa96ec07 ("net: implement XDP_REDIRECT for xdp generic")
> Fixes: 6d5fc1957989 ("xdp: Fix handling of devmap in generic XDP")
> Signed-off-by: Vladimir Oltean <[email protected]>
Sashiko has reviewed this patch and found no issues.
--
Sashiko AI review ยท
https://sashiko.dev/#/patchset/[email protected]?part=1
