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charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Maxime, On Fri, Sep 09, 2022 at 05:24:51PM +0200, Maxime Chevallier wrote: > +int dsa_oob_tag_push(struct sk_buff *skb, struct dsa_oob_tag_info *ti) > +{ > + struct dsa_oob_tag_info *tag_info; > + > + tag_info = (struct dsa_oob_tag_info *)skb->head; > + > + tag_info->proto = ti->proto; > + tag_info->dp = ti->dp; > + > + return 0; > +} > +EXPORT_SYMBOL(dsa_oob_tag_push); > + > +int dsa_oob_tag_pop(struct sk_buff *skb, struct dsa_oob_tag_info *ti) > +{ > + struct dsa_oob_tag_info *tag_info; > + > + tag_info = (struct dsa_oob_tag_info *)skb->head; > + > + if (tag_info->proto != DSA_TAG_PROTO_OOB) > + return -EINVAL; > + > + ti->proto = tag_info->proto; > + ti->dp = tag_info->dp; > + > + return 0; > +} > +EXPORT_SYMBOL(dsa_oob_tag_pop); > + > +static struct sk_buff *oob_tag_xmit(struct sk_buff *skb, > + struct net_device *dev) > +{ > + struct dsa_port *dp = dsa_slave_to_port(dev); > + struct dsa_oob_tag_info tag_info; > + > + tag_info.dp = dp->index; > + tag_info.proto = DSA_TAG_PROTO_OOB; > + > + if (dsa_oob_tag_push(skb, &tag_info)) > + return NULL; > + > + return skb; > +} I don't have too many comments on this patch set, except for a very fundamental one. It is impossible to pass a DSA out of band header between the switch tagging protocol driver and the host Ethernet controller via the beginning of skb->head, and just putting some magic bytes there and hoping that no random junk in the buffer will have the same value (and that skb_push() calls will not eat into your tag_info structure which isn't accounted for in any way by skb->data). Please create an skb extension for this, it is the only unambiguous way to deal with the given hardware, which will not give lots of headaches in the future. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel