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Commit 4ce0017a authored by Edward Cree's avatar Edward Cree Committed by David S. Miller
Browse files

net: core: another layer of lists, around PF_MEMALLOC skb handling 



First example of a layer splitting the list (rather than merely taking
 individual packets off it).
Involves new list.h function, list_cut_before(), like list_cut_position()
 but cuts on the other side of the given entry.

Signed-off-by: default avatarEdward Cree <ecree@solarflare.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 7da517a3

include/linux/list.h

+30 −0
Original line number Diff line number Diff line
@@ -285,6 +285,36 @@ static inline void list_cut_position(struct list_head *list, 
		__list_cut_position(list, head, entry);

}



/**

 * list_cut_before - cut a list into two, before given entry

 * @list: a new list to add all removed entries

 * @head: a list with entries

 * @entry: an entry within head, could be the head itself

 *

 * This helper moves the initial part of @head, up to but

 * excluding @entry, from @head to @list.  You should pass

 * in @entry an element you know is on @head.  @list should

 * be an empty list or a list you do not care about losing

 * its data.

 * If @entry == @head, all entries on @head are moved to

 * @list.

 */

static inline void list_cut_before(struct list_head *list,

				   struct list_head *head,

				   struct list_head *entry)

{

	if (head->next == entry) {

		INIT_LIST_HEAD(list);

		return;

	}

	list->next = head->next;

	list->next->prev = list;

	list->prev = entry->prev;

	list->prev->next = list;

	head->next = entry;

	entry->prev = head;

}



static inline void __list_splice(const struct list_head *list,

				 struct list_head *prev,

				 struct list_head *next)

net/core/dev.c

+36 −8
Original line number Diff line number Diff line
@@ -4784,6 +4784,14 @@ int netif_receive_skb_core(struct sk_buff *skb) 
}

EXPORT_SYMBOL(netif_receive_skb_core);



static void __netif_receive_skb_list_core(struct list_head *head, bool pfmemalloc)

{

	struct sk_buff *skb, *next;



	list_for_each_entry_safe(skb, next, head, list)

		__netif_receive_skb_core(skb, pfmemalloc);

}



static int __netif_receive_skb(struct sk_buff *skb)

{

	int ret;
@@ -4809,6 +4817,34 @@ static int __netif_receive_skb(struct sk_buff *skb) 
	return ret;

}



static void __netif_receive_skb_list(struct list_head *head)

{

	unsigned long noreclaim_flag = 0;

	struct sk_buff *skb, *next;

	bool pfmemalloc = false; /* Is current sublist PF_MEMALLOC? */



	list_for_each_entry_safe(skb, next, head, list) {

		if ((sk_memalloc_socks() && skb_pfmemalloc(skb)) != pfmemalloc) {

			struct list_head sublist;



			/* Handle the previous sublist */

			list_cut_before(&sublist, head, &skb->list);

			__netif_receive_skb_list_core(&sublist, pfmemalloc);

			pfmemalloc = !pfmemalloc;

			/* See comments in __netif_receive_skb */

			if (pfmemalloc)

				noreclaim_flag = memalloc_noreclaim_save();

			else

				memalloc_noreclaim_restore(noreclaim_flag);

		}

	}

	/* Handle the remaining sublist */

	__netif_receive_skb_list_core(head, pfmemalloc);

	/* Restore pflags */

	if (pfmemalloc)

		memalloc_noreclaim_restore(noreclaim_flag);

}



static int generic_xdp_install(struct net_device *dev, struct netdev_bpf *xdp)

{

	struct bpf_prog *old = rtnl_dereference(dev->xdp_prog);
@@ -4843,14 +4879,6 @@ static int generic_xdp_install(struct net_device *dev, struct netdev_bpf *xdp) 
	return ret;

}



static void __netif_receive_skb_list(struct list_head *head)

{

	struct sk_buff *skb, *next;



	list_for_each_entry_safe(skb, next, head, list)

		__netif_receive_skb(skb);

}



static int netif_receive_skb_internal(struct sk_buff *skb)

{

	int ret;