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Subject: Re: [PATCH v3 01/13] mac80211: rework tx encapsulation offload API
From:   Johannes Berg <johannes@sipsolutions.net>
To:     Felix Fietkau <nbd@nbd.name>, linux-wireless@vger.kernel.org
Date:   Thu, 27 Aug 2020 14:42:07 +0200
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I was going to not worry about it, but now that I'm replying anyway ...

> +++ b/net/mac80211/iface.c
> @@ -43,6 +43,7 @@
>   */
>  
>  static void ieee80211_iface_work(struct work_struct *work);
> +static void ieee80211_set_vif_encap_ops(struct ieee80211_sub_if_data *sdata);

Do we really need that, can can't reorder things?

> +static bool ieee80211_iftype_supports_encap_offload(enum nl80211_iftype iftype)
> +{
> +	switch (iftype) {
> +	case NL80211_IFTYPE_AP:
> +	case NL80211_IFTYPE_P2P_GO:
> +	case NL80211_IFTYPE_P2P_CLIENT:

The P2P ones cannot happen here due to the iftype munging that mac80211
does, suggest you add a comment about that and remove them.

> +		list_for_each_entry(key, &sdata->key_list, list) {
> +			if (key->conf.cipher == WLAN_CIPHER_SUITE_AES_CMAC ||
> +			    key->conf.cipher == WLAN_CIPHER_SUITE_BIP_GMAC_128 ||
> +			    key->conf.cipher == WLAN_CIPHER_SUITE_BIP_GMAC_256 ||
> +			    key->conf.cipher == WLAN_CIPHER_SUITE_BIP_CMAC_256)
> +				continue;

I had to read that a few times to understand it ... maybe add a comment
that the management frame keys aren't relevant? :)


But anyway, what I was really not sure about is this function:

> +static void ieee80211_set_vif_encap_ops(struct ieee80211_sub_if_data *sdata)
> +{
> +	struct ieee80211_local *local = sdata->local;
> +	struct ieee80211_sub_if_data *bss = sdata;
> +	struct ieee80211_key *key;
> +	bool enabled;
> +
> +	if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN) {
> +		if (!sdata->bss)
> +			return;
> +
> +		bss = container_of(sdata->bss, struct ieee80211_sub_if_data, u.ap);
> +	}
> +
> +	if (!ieee80211_hw_check(&local->hw, SUPPORTS_TX_ENCAP_OFFLOAD) ||
> +	    !ieee80211_iftype_supports_encap_offload(bss->vif.type))
> +		return;

There are a lot of returns here, some of which make sense, but the
sdata->bss one seems dynamic and doesn't really make sense? Could it
change?

Or maybe we don't care because if it's not linked to a BSS it cannot be
transmitting?

johannes