Commit 2b67f944 authored by Felix Fietkau's avatar Felix Fietkau Committed by Johannes Berg
Browse files

cfg80211: reuse existing page fragments in A-MSDU rx 



This massively reduces data copying and thus improves rx performance

Signed-off-by: default avatarFelix Fietkau <nbd@openwrt.org>
Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
parent 2bf0ccc7

net/wireless/util.c

+77 −5
Original line number Diff line number Diff line
@@ -644,23 +644,93 @@ int ieee80211_data_from_8023(struct sk_buff *skb, const u8 *addr, 
}

EXPORT_SYMBOL(ieee80211_data_from_8023);



static void

__frame_add_frag(struct sk_buff *skb, struct page *page,

		 void *ptr, int len, int size)

{

	struct skb_shared_info *sh = skb_shinfo(skb);

	int page_offset;



	atomic_inc(&page->_count);

	page_offset = ptr - page_address(page);

	skb_add_rx_frag(skb, sh->nr_frags, page, page_offset, len, size);

}



static void

__ieee80211_amsdu_copy_frag(struct sk_buff *skb, struct sk_buff *frame,

			    int offset, int len)

{

	struct skb_shared_info *sh = skb_shinfo(skb);

	const skb_frag_t *frag = &sh->frags[-1];

	struct page *frag_page;

	void *frag_ptr;

	int frag_len, frag_size;

	int head_size = skb->len - skb->data_len;

	int cur_len;



	frag_page = virt_to_head_page(skb->head);

	frag_ptr = skb->data;

	frag_size = head_size;



	while (offset >= frag_size) {

		offset -= frag_size;

		frag++;

		frag_page = skb_frag_page(frag);

		frag_ptr = skb_frag_address(frag);

		frag_size = skb_frag_size(frag);

	}



	frag_ptr += offset;

	frag_len = frag_size - offset;



	cur_len = min(len, frag_len);



	__frame_add_frag(frame, frag_page, frag_ptr, cur_len, frag_size);

	len -= cur_len;



	while (len > 0) {

		frag++;

		frag_len = skb_frag_size(frag);

		cur_len = min(len, frag_len);

		__frame_add_frag(frame, skb_frag_page(frag),

				 skb_frag_address(frag), cur_len, frag_len);

		len -= cur_len;

	}

}



static struct sk_buff *

__ieee80211_amsdu_copy(struct sk_buff *skb, unsigned int hlen,

		       int offset, int len)

		       int offset, int len, bool reuse_frag)

{

	struct sk_buff *frame;

	int cur_len = len;



	if (skb->len - offset < len)

		return NULL;



	/*

	 * When reusing framents, copy some data to the head to simplify

	 * ethernet header handling and speed up protocol header processing

	 * in the stack later.

	 */

	if (reuse_frag)

		cur_len = min_t(int, len, 32);



	/*

	 * Allocate and reserve two bytes more for payload

	 * alignment since sizeof(struct ethhdr) is 14.

	 */

	frame = dev_alloc_skb(hlen + sizeof(struct ethhdr) + 2 + len);

	frame = dev_alloc_skb(hlen + sizeof(struct ethhdr) + 2 + cur_len);



	skb_reserve(frame, hlen + sizeof(struct ethhdr) + 2);

	skb_copy_bits(skb, offset, skb_put(frame, len), len);

	skb_copy_bits(skb, offset, skb_put(frame, cur_len), cur_len);



	len -= cur_len;

	if (!len)

		return frame;



	offset += cur_len;

	__ieee80211_amsdu_copy_frag(skb, frame, offset, len);



	return frame;

}
@@ -676,6 +746,7 @@ void ieee80211_amsdu_to_8023s(struct sk_buff *skb, struct sk_buff_head *list, 
	u8 *payload;

	int offset = 0, remaining, err;

	struct ethhdr eth;

	bool reuse_frag = skb->head_frag && !skb_has_frag_list(skb);

	bool reuse_skb = false;

	bool last = false;
@@ -703,12 +774,13 @@ void ieee80211_amsdu_to_8023s(struct sk_buff *skb, struct sk_buff_head *list, 
		offset += sizeof(struct ethhdr);

		/* reuse skb for the last subframe */

		last = remaining <= subframe_len + padding;

		if (!skb_is_nonlinear(skb) && last) {

		if (!skb_is_nonlinear(skb) && !reuse_frag && last) {

			skb_pull(skb, offset);

			frame = skb;

			reuse_skb = true;

		} else {

			frame = __ieee80211_amsdu_copy(skb, hlen, offset, len);

			frame = __ieee80211_amsdu_copy(skb, hlen, offset, len,

						       reuse_frag);

			if (!frame)

				goto purge;