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

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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: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Edward Cree 2018-07-02 16:13:40 +01:00 committed by David S. Miller
parent 7da517a3bc
commit 4ce0017a37
2 changed files with 66 additions and 8 deletions
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30
include/linux/list.h
View File

@ -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)

44
net/core/dev.c
View File

@ -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;