netdev - Re: [PATCH net-next 4/7] net: openvswitch: add misc error drop reasons

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Date: Wed, 26 Jul 2023 10:32:52 +0200
From: Adrian Moreno <amorenoz@...hat.com>
To: Aaron Conole <aconole@...hat.com>
Cc: netdev@...r.kernel.org, dev@...nvswitch.org, i.maximets@....org,
 eric@...ver.life
Subject: Re: [PATCH net-next 4/7] net: openvswitch: add misc error drop
 reasons



On 7/24/23 17:23, Aaron Conole wrote:
> Adrian Moreno <amorenoz@...hat.com> writes:
> 
>> Use drop reasons from include/net/dropreason-core.h when a reasonable
>> candidate exists.
>>
>> Signed-off-by: Adrian Moreno <amorenoz@...hat.com>
>> ---
>>   net/openvswitch/actions.c   | 17 ++++++++++-------
>>   net/openvswitch/conntrack.c |  3 ++-
>>   net/openvswitch/drop.h      |  6 ++++++
>>   3 files changed, 18 insertions(+), 8 deletions(-)
>>
>> diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
>> index 9279bb186e9f..42fa1e7eb912 100644
>> --- a/net/openvswitch/actions.c
>> +++ b/net/openvswitch/actions.c
> 
> Did you consider putting in a drop reason when one of the actions fails
> setting err?  For example, if dec_ttl fails with some error other than
> EHOSTUNREACH, it will drop into the kfree_skb() case... maybe we should
> have an action_failed drop reason that can be passed there.
> 

Another good idea! Thanks Aaron.


>> @@ -782,7 +782,7 @@ static int ovs_vport_output(struct net *net, struct sock *sk,
>>   	struct vport *vport = data->vport;
>>   
>>   	if (skb_cow_head(skb, data->l2_len) < 0) {
>> -		kfree_skb(skb);
>> +		kfree_skb_reason(skb, SKB_DROP_REASON_NOMEM);
>>   		return -ENOMEM;
>>   	}
>>   
>> @@ -853,6 +853,7 @@ static void ovs_fragment(struct net *net, struct vport *vport,
>>   			 struct sk_buff *skb, u16 mru,
>>   			 struct sw_flow_key *key)
>>   {
>> +	enum ovs_drop_reason reason;
>>   	u16 orig_network_offset = 0;
>>   
>>   	if (eth_p_mpls(skb->protocol)) {
>> @@ -862,6 +863,7 @@ static void ovs_fragment(struct net *net, struct vport *vport,
>>   
>>   	if (skb_network_offset(skb) > MAX_L2_LEN) {
>>   		OVS_NLERR(1, "L2 header too long to fragment");
>> +		reason = OVS_DROP_FRAG_L2_TOO_LONG;
>>   		goto err;
>>   	}
>>   
>> @@ -902,12 +904,13 @@ static void ovs_fragment(struct net *net, struct vport *vport,
>>   		WARN_ONCE(1, "Failed fragment ->%s: eth=%04x, MRU=%d, MTU=%d.",
>>   			  ovs_vport_name(vport), ntohs(key->eth.type), mru,
>>   			  vport->dev->mtu);
>> +		reason = OVS_DROP_FRAG_INVALID_PROTO;
>>   		goto err;
>>   	}
>>   
>>   	return;
>>   err:
>> -	kfree_skb(skb);
>> +	kfree_skb_reason(skb, reason);
>>   }
>>   
>>   static void do_output(struct datapath *dp, struct sk_buff *skb, int out_port,
>> @@ -934,10 +937,10 @@ static void do_output(struct datapath *dp, struct sk_buff *skb, int out_port,
>>   
>>   			ovs_fragment(net, vport, skb, mru, key);
>>   		} else {
>> -			kfree_skb(skb);
>> +			kfree_skb_reason(skb, SKB_DROP_REASON_PKT_TOO_BIG);
>>   		}
>>   	} else {
>> -		kfree_skb(skb);
>> +		kfree_skb_reason(skb, SKB_DROP_REASON_DEV_READY);
>>   	}
>>   }
>>   
>> @@ -1011,7 +1014,7 @@ static int dec_ttl_exception_handler(struct datapath *dp, struct sk_buff *skb,
>>   		return clone_execute(dp, skb, key, 0, nla_data(actions),
>>   				     nla_len(actions), true, false);
>>   
>> -	consume_skb(skb);
>> +	kfree_skb_reason(skb, OVS_DROP_IP_TTL);
>>   	return 0;
>>   }
>>   
>> @@ -1564,7 +1567,7 @@ static int clone_execute(struct datapath *dp, struct sk_buff *skb,
>>   		/* Out of per CPU action FIFO space. Drop the 'skb' and
>>   		 * log an error.
>>   		 */
>> -		kfree_skb(skb);
>> +		kfree_skb_reason(skb, OVS_DROP_DEFERRED_LIMIT);
>>   
>>   		if (net_ratelimit()) {
>>   			if (actions) { /* Sample action */
>> @@ -1616,7 +1619,7 @@ int ovs_execute_actions(struct datapath *dp, struct sk_buff *skb,
>>   	if (unlikely(level > OVS_RECURSION_LIMIT)) {
>>   		net_crit_ratelimited("ovs: recursion limit reached on datapath %s, probable configuration error\n",
>>   				     ovs_dp_name(dp));
>> -		kfree_skb(skb);
>> +		kfree_skb_reason(skb, OVS_DROP_RECURSION_LIMIT);
>>   		err = -ENETDOWN;
>>   		goto out;
>>   	}
>> diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c
>> index fa955e892210..b03ebd4a8fae 100644
>> --- a/net/openvswitch/conntrack.c
>> +++ b/net/openvswitch/conntrack.c
>> @@ -29,6 +29,7 @@
>>   #include <net/netfilter/nf_conntrack_act_ct.h>
>>   
>>   #include "datapath.h"
>> +#include "drop.h"
>>   #include "conntrack.h"
>>   #include "flow.h"
>>   #include "flow_netlink.h"
>> @@ -1035,7 +1036,7 @@ int ovs_ct_execute(struct net *net, struct sk_buff *skb,
>>   
>>   	skb_push_rcsum(skb, nh_ofs);
>>   	if (err)
>> -		kfree_skb(skb);
>> +		kfree_skb_reason(skb, OVS_DROP_CONNTRACK);
>>   	return err;
>>   }
>>   
>> diff --git a/net/openvswitch/drop.h b/net/openvswitch/drop.h
>> index 2440c836727f..744b8d1b93a3 100644
>> --- a/net/openvswitch/drop.h
>> +++ b/net/openvswitch/drop.h
>> @@ -12,6 +12,12 @@
>>   	R(OVS_DROP_EXPLICIT_ACTION)		\
>>   	R(OVS_DROP_EXPLICIT_ACTION_ERROR)	\
>>   	R(OVS_DROP_METER)			\
>> +	R(OVS_DROP_RECURSION_LIMIT)		\
>> +	R(OVS_DROP_DEFERRED_LIMIT)		\
>> +	R(OVS_DROP_FRAG_L2_TOO_LONG)		\
>> +	R(OVS_DROP_FRAG_INVALID_PROTO)		\
>> +	R(OVS_DROP_CONNTRACK)			\
>> +	R(OVS_DROP_IP_TTL)			\
>>   	/* deliberate comment for trailing \ */
>>   
>>   enum ovs_drop_reason {
>