Commit 09c2c907 authored by Eric Dumazet's avatar Eric Dumazet Committed by Jakub Kicinski
Browse files

net: allow alloc_skb_with_frags() to allocate bigger packets 

Refactor alloc_skb_with_frags() to allow bigger packets allocations.

Instead of assuming that only order-0 allocations will be attempted,
use the caller supplied max order.

v2: try harder to use high-order pages, per Willem feedback.

Link: https://lore.kernel.org/netdev/CANn89iJQfmc_KeUr3TeXvsLQwo3ZymyoCr7Y6AnHrkWSuz0yAg@mail.gmail.com/


Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Cc: Tahsin Erdogan <trdgn@amazon.com>
Reviewed-by: default avatarWillem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20230801205254.400094-2-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 49c467dc

net/core/skbuff.c

+25 −31
Original line number Diff line number Diff line
@@ -6204,7 +6204,7 @@ EXPORT_SYMBOL_GPL(skb_mpls_dec_ttl); 
 *

 * @header_len: size of linear part

 * @data_len: needed length in frags

 * @max_page_order: max page order desired.

 * @order: max page order desired.

 * @errcode: pointer to error code if any

 * @gfp_mask: allocation mask

 *
@@ -6212,21 +6212,17 @@ EXPORT_SYMBOL_GPL(skb_mpls_dec_ttl); 
 */

struct sk_buff *alloc_skb_with_frags(unsigned long header_len,

				     unsigned long data_len,

				     int max_page_order,

				     int order,

				     int *errcode,

				     gfp_t gfp_mask)

{

	int npages = (data_len + (PAGE_SIZE - 1)) >> PAGE_SHIFT;

	unsigned long chunk;

	struct sk_buff *skb;

	struct page *page;

	int i;

	int nr_frags = 0;



	*errcode = -EMSGSIZE;

	/* Note this test could be relaxed, if we succeed to allocate

	 * high order pages...

	 */

	if (npages > MAX_SKB_FRAGS)

	if (unlikely(data_len > MAX_SKB_FRAGS * (PAGE_SIZE << order)))

		return NULL;



	*errcode = -ENOBUFS;
@@ -6234,34 +6230,32 @@ struct sk_buff *alloc_skb_with_frags(unsigned long header_len, 
	if (!skb)

		return NULL;



	skb->truesize += npages << PAGE_SHIFT;



	for (i = 0; npages > 0; i++) {

		int order = max_page_order;

	while (data_len) {

		if (nr_frags == MAX_SKB_FRAGS - 1)

			goto failure;

		while (order && PAGE_ALIGN(data_len) < (PAGE_SIZE << order))

			order--;



		while (order) {

			if (npages >= 1 << order) {

		if (order) {

			page = alloc_pages((gfp_mask & ~__GFP_DIRECT_RECLAIM) |

					   __GFP_COMP |

					   __GFP_NOWARN,

					   order);

				if (page)

					goto fill_page;

				/* Do not retry other high order allocations */

				order = 1;

				max_page_order = 0;

			}

			if (!page) {

				order--;

				continue;

			}

		} else {

			page = alloc_page(gfp_mask);

			if (!page)

				goto failure;

fill_page:

		}

		chunk = min_t(unsigned long, data_len,

			      PAGE_SIZE << order);

		skb_fill_page_desc(skb, i, page, 0, chunk);

		skb_fill_page_desc(skb, nr_frags, page, 0, chunk);

		nr_frags++;

		skb->truesize += (PAGE_SIZE << order);

		data_len -= chunk;

		npages -= 1 << order;

	}

	return skb;