netdev - Re: [PATCH net-next 3/3] cls_flower: Allow flow offloading though masked key exist.

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Message-ID: <20200619140157.GB2182@nanopsycho>
Date:   Fri, 19 Jun 2020 16:01:57 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     dsatish <satish.d@...convergence.com>
Cc:     davem@...emloft.net, jhs@...atatu.com, xiyou.wangcong@...il.com,
        kuba@...nel.org, netdev@...r.kernel.org,
        simon.horman@...ronome.com, kesavac@...il.com,
        prathibha.nagooru@...convergence.com,
        intiyaz.basha@...convergence.com, jai.rana@...convergence.com
Subject: Re: [PATCH net-next 3/3] cls_flower: Allow flow offloading though
 masked key exist.

Fri, Jun 19, 2020 at 11:41:56AM CEST, satish.d@...convergence.com wrote:
>A packet reaches OVS user space, only if, either there is no rule in
>datapath/hardware or there is race condition that the flow is added
>to hardware but before it is processed another packet arrives.
>
>It is possible hardware as part of its limitations/optimizations
>remove certain flows. To handle such cases where the hardware lost
>the flows, tc can offload to hardware if it receives a flow for which
>there exists an entry in its flow table. To handle such cases TC when
>it returns EEXIST error, also programs the flow in hardware, if
>hardware offload is enabled.
>
>Signed-off-by: Chandra Kesava <kesavac@...il.com>
>Signed-off-by: Prathibha Nagooru <prathibha.nagooru@...convergence.com>
>Signed-off-by: Satish Dhote <satish.d@...convergence.com>
>---
> net/sched/cls_flower.c | 23 +++++++++++++++++++----
> 1 file changed, 19 insertions(+), 4 deletions(-)
>
>diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
>index f1a5352cbb04..d718233cd5b9 100644
>--- a/net/sched/cls_flower.c
>+++ b/net/sched/cls_flower.c
>@@ -431,7 +431,8 @@ static void fl_hw_destroy_filter(struct tcf_proto *tp, struct cls_fl_filter *f,
> 
> static int fl_hw_replace_filter(struct tcf_proto *tp,
> 				struct cls_fl_filter *f, bool rtnl_held,
>-				struct netlink_ext_ack *extack)
>+				struct netlink_ext_ack *extack,
>+				unsigned long cookie)
> {
> 	struct tcf_block *block = tp->chain->block;
> 	struct flow_cls_offload cls_flower = {};
>@@ -444,7 +445,7 @@ static int fl_hw_replace_filter(struct tcf_proto *tp,
> 
> 	tc_cls_common_offload_init(&cls_flower.common, tp, f->flags, extack);
> 	cls_flower.command = FLOW_CLS_REPLACE;
>-	cls_flower.cookie = (unsigned long) f;
>+	cls_flower.cookie = cookie;
> 	cls_flower.rule->match.dissector = &f->mask->dissector;
> 	cls_flower.rule->match.mask = &f->mask->key;
> 	cls_flower.rule->match.key = &f->mkey;
>@@ -2024,11 +2025,25 @@ static int fl_change(struct net *net, struct sk_buff *in_skb,
> 	fl_init_unmasked_key_dissector(&fnew->unmasked_key_dissector);
> 
> 	err = fl_ht_insert_unique(fnew, fold, &in_ht);
>-	if (err)
>+	if (err) {
>+		/* It is possible Hardware lost the flow even though TC has it,
>+		 * and flow miss in hardware causes controller to offload flow again.

What? Seems that you have a buggy HW what should be fixed...

What is "controller"?


>+		 */
>+		if (err == -EEXIST && !tc_skip_hw(fnew->flags)) {
>+			struct cls_fl_filter *f =
>+				__fl_lookup(fnew->mask, &fnew->mkey);
>+
>+			if (f)
>+				fl_hw_replace_filter(tp, fnew, rtnl_held,
>+						     extack,
>+						     (unsigned long)(f));
>+		}
> 		goto errout_mask;
>+	}
> 
> 	if (!tc_skip_hw(fnew->flags)) {
>-		err = fl_hw_replace_filter(tp, fnew, rtnl_held, extack);
>+		err = fl_hw_replace_filter(tp, fnew, rtnl_held, extack,
>+					   (unsigned long)fnew);
> 		if (err)
> 			goto errout_ht;
> 	}
>-- 
>2.17.1
>