Commit 9f6b619e authored by Mina Almasry's avatar Mina Almasry Committed by Jakub Kicinski
Browse files

net: support non paged skb frags 



Make skb_frag_page() fail in the case where the frag is not backed
by a page, and fix its relevant callers to handle this case.

Signed-off-by: default avatarMina Almasry <almasrymina@google.com>
Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarJakub Kicinski <kuba@kernel.org>
Link: https://patch.msgid.link/20240910171458.219195-8-almasrymina@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 0f921404

include/linux/skbuff.h

+41 −1
Original line number Diff line number Diff line
@@ -3524,21 +3524,58 @@ static inline void skb_frag_off_copy(skb_frag_t *fragto, 
	fragto->offset = fragfrom->offset;

}



/* Return: true if the skb_frag contains a net_iov. */

static inline bool skb_frag_is_net_iov(const skb_frag_t *frag)

{

	return netmem_is_net_iov(frag->netmem);

}



/**

 * skb_frag_net_iov - retrieve the net_iov referred to by fragment

 * @frag: the fragment

 *

 * Return: the &struct net_iov associated with @frag. Returns NULL if this

 * frag has no associated net_iov.

 */

static inline struct net_iov *skb_frag_net_iov(const skb_frag_t *frag)

{

	if (!skb_frag_is_net_iov(frag))

		return NULL;



	return netmem_to_net_iov(frag->netmem);

}



/**

 * skb_frag_page - retrieve the page referred to by a paged fragment

 * @frag: the paged fragment

 *

 * Returns the &struct page associated with @frag.

 * Return: the &struct page associated with @frag. Returns NULL if this frag

 * has no associated page.

 */

static inline struct page *skb_frag_page(const skb_frag_t *frag)

{

	if (skb_frag_is_net_iov(frag))

		return NULL;



	return netmem_to_page(frag->netmem);

}



/**

 * skb_frag_netmem - retrieve the netmem referred to by a fragment

 * @frag: the fragment

 *

 * Return: the &netmem_ref associated with @frag.

 */

static inline netmem_ref skb_frag_netmem(const skb_frag_t *frag)

{

	return frag->netmem;

}



int skb_pp_cow_data(struct page_pool *pool, struct sk_buff **pskb,

		    unsigned int headroom);

int skb_cow_data_for_xdp(struct page_pool *pool, struct sk_buff **pskb,

			 struct bpf_prog *prog);



/**

 * skb_frag_address - gets the address of the data contained in a paged fragment

 * @frag: the paged fragment buffer
@@ -3548,6 +3585,9 @@ int skb_cow_data_for_xdp(struct page_pool *pool, struct sk_buff **pskb, 
 */

static inline void *skb_frag_address(const skb_frag_t *frag)

{

	if (!skb_frag_page(frag))

		return NULL;



	return page_address(skb_frag_page(frag)) + skb_frag_off(frag);

}

include/linux/skbuff_ref.h

+4 −5
Original line number Diff line number Diff line
@@ -34,14 +34,13 @@ static inline void skb_frag_ref(struct sk_buff *skb, int f) 


bool napi_pp_put_page(netmem_ref netmem);



static inline void

skb_page_unref(struct page *page, bool recycle)

static inline void skb_page_unref(netmem_ref netmem, bool recycle)

{

#ifdef CONFIG_PAGE_POOL

	if (recycle && napi_pp_put_page(page_to_netmem(page)))

	if (recycle && napi_pp_put_page(netmem))

		return;

#endif

	put_page(page);

	put_page(netmem_to_page(netmem));

}



/**
@@ -54,7 +53,7 @@ skb_page_unref(struct page *page, bool recycle) 
 */

static inline void __skb_frag_unref(skb_frag_t *frag, bool recycle)

{

	skb_page_unref(skb_frag_page(frag), recycle);

	skb_page_unref(skb_frag_netmem(frag), recycle);

}



/**

net/core/dev.c

+2 −1
Original line number Diff line number Diff line
@@ -3434,8 +3434,9 @@ static int illegal_highdma(struct net_device *dev, struct sk_buff *skb) 
	if (!(dev->features & NETIF_F_HIGHDMA)) {

		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {

			skb_frag_t *frag = &skb_shinfo(skb)->frags[i];

			struct page *page = skb_frag_page(frag);



			if (PageHighMem(skb_frag_page(frag)))

			if (page && PageHighMem(page))

				return 1;

		}

	}

net/core/gro.c

+2 −1
Original line number Diff line number Diff line
@@ -408,7 +408,8 @@ static inline void skb_gro_reset_offset(struct sk_buff *skb, u32 nhoff) 
	pinfo = skb_shinfo(skb);

	frag0 = &pinfo->frags[0];



	if (pinfo->nr_frags && !PageHighMem(skb_frag_page(frag0)) &&

	if (pinfo->nr_frags && skb_frag_page(frag0) &&

	    !PageHighMem(skb_frag_page(frag0)) &&

	    (!NET_IP_ALIGN || !((skb_frag_off(frag0) + nhoff) & 3))) {

		NAPI_GRO_CB(skb)->frag0 = skb_frag_address(frag0);

		NAPI_GRO_CB(skb)->frag0_len = min_t(unsigned int,

net/core/skbuff.c

+11 −0
Original line number Diff line number Diff line
@@ -1371,6 +1371,14 @@ void skb_dump(const char *level, const struct sk_buff *skb, bool full_pkt) 
		struct page *p;

		u8 *vaddr;



		if (skb_frag_is_net_iov(frag)) {

			printk("%sskb frag %d: not readable\n", level, i);

			len -= skb_frag_size(frag);

			if (!len)

				break;

			continue;

		}



		skb_frag_foreach_page(frag, skb_frag_off(frag),

				      skb_frag_size(frag), p, p_off, p_len,

				      copied) {
@@ -3163,6 +3171,9 @@ static bool __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe, 
	for (seg = 0; seg < skb_shinfo(skb)->nr_frags; seg++) {

		const skb_frag_t *f = &skb_shinfo(skb)->frags[seg];



		if (WARN_ON_ONCE(!skb_frag_page(f)))

			return false;



		if (__splice_segment(skb_frag_page(f),

				     skb_frag_off(f), skb_frag_size(f),

				     offset, len, spd, false, sk, pipe))