On Thu, Jun 29, 2023 at 04:30:05PM -0400, Eric Garver wrote:
> This adds an explicit drop action. This is used by OVS to drop packets
> for which it cannot determine what to do. An explicit action in the
> kernel allows passing the reason _why_ the packet is being dropped. We
> can then use perf tracing to match on the drop reason.
>
> e.g. trace all OVS dropped skbs
>
> # perf trace -e skb:kfree_skb --filter="reason >= 0x30000"
> [..]
> 106.023 ping/2465 skb:kfree_skb(skbaddr: 0xffffa0e8765f2000, \
> location:0xffffffffc0d9b462, protocol: 2048, reason: 196610)
>
> reason: 196610 --> 0x30002 (OVS_XLATE_RECURSION_TOO_DEEP)
>
> Signed-off-by: Eric Garver <e...@garver.life>
...
> --- a/net/openvswitch/actions.c
> +++ b/net/openvswitch/actions.c
> @@ -32,6 +32,7 @@
> #include "vport.h"
> #include "flow_netlink.h"
> #include "openvswitch_trace.h"
> +#include "drop.h"
>
> struct deferred_action {
> struct sk_buff *skb;
> @@ -1477,6 +1478,18 @@ static int do_execute_actions(struct datapath *dp,
> struct sk_buff *skb,
> return dec_ttl_exception_handler(dp, skb,
> key, a);
> break;
> +
> + case OVS_ACTION_ATTR_DROP:
> + u32 reason = nla_get_u32(a);
> +
> + reason |= SKB_DROP_REASON_SUBSYS_OPENVSWITCH <<
> + SKB_DROP_REASON_SUBSYS_SHIFT;
> +
> + if (reason == OVS_XLATE_OK)
> + break;
> +
> + kfree_skb_reason(skb, reason);
> + return 0;
> }
Hi Eric,
thanks for your patches. This is an interesting new feature.
unfortunately clang-16 doesn't seem to like this very much.
I think that it is due to the declaration of reason not
being enclosed in a block - { }.
net/openvswitch/actions.c:1483:4: error: expected expression
u32 reason = nla_get_u32(a);
^
net/openvswitch/actions.c:1485:4: error: use of undeclared identifier 'reason'
reason |= SKB_DROP_REASON_SUBSYS_OPENVSWITCH <<
^
net/openvswitch/actions.c:1488:8: error: use of undeclared identifier 'reason'
if (reason == OVS_XLATE_OK)
^
net/openvswitch/actions.c:1491:26: error: use of undeclared identifier
'reason'
kfree_skb_reason(skb, reason);
^
4 errors generated.
net-next is currently closed.
So please provide a v2 once it reposts, after 10th July.
See:
https://www.kernel.org/doc/html/next/process/maintainer-netdev.html#development-cycle
--
pw-bot: changes-requested
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