mac80211: allow checksum offload only in fast-xmit (2d981fdd) · Commits · 戴 / test

When we go through the complete TX processing, there are a number of things like fragmentation and software crypto that require the checksum to be calculated already. In favour of maintainability, instead of adding the necessary call to skb_checksum_help() in all the places that need it, just do it once before the regular TX processing. Right now this only affects the TI wlcore and QCA ath10k drivers since they're the only ones using checksum offload. The previous commits enabled fast-xmit for them in almost all cases. For wlcore this even fixes a corner case: when a key fails to be programmed to hardware software encryption gets used, encrypting frames with a bad checksum. Signed-off-by:

Johannes Berg <johannes.berg@intel.com>

net/mac80211/tx.c

+20 −4

Original line number	Diff line number	Diff line
		@@ -2851,10 +2851,8 @@ void __ieee80211_subif_start_xmit(struct sk_buff *skb,

		rcu_read_lock();

		if (ieee80211_lookup_ra_sta(sdata, skb, &sta)) {
		kfree_skb(skb);
		goto out;
		}
		if (ieee80211_lookup_ra_sta(sdata, skb, &sta))
		goto out_free;

		if (!IS_ERR_OR_NULL(sta)) {
		struct ieee80211_fast_tx *fast_tx;
		@@ -2866,6 +2864,21 @@ void __ieee80211_subif_start_xmit(struct sk_buff *skb,
		goto out;
		}

		/* the frame could be fragmented, software-encrypted, and other things
		* so we cannot really handle checksum offload with it - fix it up in
		* software before we handle anything else.
		*/
		if (skb->ip_summed == CHECKSUM_PARTIAL) {
		if (skb->encapsulation)
		skb_set_inner_transport_header(skb,
		skb_checksum_start_offset(skb));
		else
		skb_set_transport_header(skb,
		skb_checksum_start_offset(skb));
		if (skb_checksum_help(skb))
		goto out_free;
		}

		skb = ieee80211_build_hdr(sdata, skb, info_flags, sta);
		if (IS_ERR(skb))
		goto out;
		@@ -2875,6 +2888,9 @@ void __ieee80211_subif_start_xmit(struct sk_buff *skb,
		dev->trans_start = jiffies;

		ieee80211_xmit(sdata, sta, skb);
		goto out;
		out_free:
		kfree_skb(skb);
		out:
		rcu_read_unlock();
		}

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