Hi,
This patch fills in some missing pieces:
* Support v4 udp: same as v4 tcp, when in reserve, drop packets on
noncritical sockets
* Support v4 icmp: when in reserve, drop icmp traffic
* Add reserve skb support to e1000 driver
* API for dropping packets before delivery (dev_drop_skb)
* Atomic_t for reserve accounting
Now ready for proof-of-concept testing. High level API boilerplate will come
later.
Regards,
Daniel
diff -up --recursive 2.6.12.3.clean/drivers/net/e1000/e1000_main.c
2.6.12.3/drivers/net/e1000/e1000_main.c
--- 2.6.12.3.clean/drivers/net/e1000/e1000_main.c 2005-07-15
17:18:57.000000000 -0400
+++ 2.6.12.3/drivers/net/e1000/e1000_main.c 2005-08-06 16:46:13.000000000
-0400
@@ -3242,7 +3242,7 @@ e1000_alloc_rx_buffers_ps(struct e1000_a
cpu_to_le64(ps_page_dma->ps_page_dma[j]);
}
- skb = dev_alloc_skb(adapter->rx_ps_bsize0 + NET_IP_ALIGN);
+ skb = dev_memalloc_skb(netdev, adapter->rx_ps_bsize0 +
NET_IP_ALIGN);
if(unlikely(!skb))
break;
@@ -3253,8 +3253,6 @@ e1000_alloc_rx_buffers_ps(struct e1000_a
*/
skb_reserve(skb, NET_IP_ALIGN);
- skb->dev = netdev;
-
buffer_info->skb = skb;
buffer_info->length = adapter->rx_ps_bsize0;
buffer_info->dma = pci_map_single(pdev, skb->data,
diff -up --recursive 2.6.12.3.clean/include/linux/gfp.h
2.6.12.3/include/linux/gfp.h
--- 2.6.12.3.clean/include/linux/gfp.h 2005-07-15 17:18:57.000000000 -0400
+++ 2.6.12.3/include/linux/gfp.h 2005-08-05 21:53:09.000000000 -0400
@@ -39,6 +39,7 @@ struct vm_area_struct;
#define __GFP_COMP 0x4000u /* Add compound page metadata */
#define __GFP_ZERO 0x8000u /* Return zeroed page on success */
#define __GFP_NOMEMALLOC 0x10000u /* Don't use emergency reserves */
+#define __GFP_MEMALLOC 0x20000u /* Use emergency reserves */
#define __GFP_BITS_SHIFT 20 /* Room for 20 __GFP_FOO bits */
#define __GFP_BITS_MASK ((1 << __GFP_BITS_SHIFT) - 1)
diff -up --recursive 2.6.12.3.clean/include/linux/netdevice.h
2.6.12.3/include/linux/netdevice.h
--- 2.6.12.3.clean/include/linux/netdevice.h 2005-07-15 17:18:57.000000000
-0400
+++ 2.6.12.3/include/linux/netdevice.h 2005-08-06 16:37:14.000000000 -0400
@@ -371,6 +371,8 @@ struct net_device
struct Qdisc *qdisc_ingress;
struct list_head qdisc_list;
unsigned long tx_queue_len; /* Max frames per queue allowed
*/
+ int rx_reserve;
+ atomic_t rx_reserve_used;
/* ingress path synchronizer */
spinlock_t ingress_lock;
@@ -662,6 +664,49 @@ static inline void dev_kfree_skb_any(str
dev_kfree_skb(skb);
}
+/*
+ * Support for critical network IO under low memory conditions
+ */
+static inline int dev_reserve_used(struct net_device *dev)
+{
+ return atomic_read(&dev->rx_reserve_used);
+}
+
+static inline struct sk_buff *__dev_memalloc_skb(struct net_device *dev,
+ unsigned length, int gfp_mask)
+{
+ struct sk_buff *skb = __dev_alloc_skb(length, gfp_mask);
+ if (skb)
+ goto done;
+ if (dev_reserve_used(dev) >= dev->rx_reserve)
+ return NULL;
+ if (!__dev_alloc_skb(length, gfp_mask|__GFP_MEMALLOC))
+ return NULL;;
+ atomic_inc(&dev->rx_reserve_used);
+done:
+ skb->dev = dev;
+ return skb;
+}
+
+static inline struct sk_buff *dev_memalloc_skb(struct net_device *dev,
+ unsigned length)
+{
+ return __dev_memalloc_skb(dev, length, GFP_ATOMIC);
+}
+
+static inline void dev_unreserve(struct net_device *dev)
+{
+ if (atomic_dec_return(&dev->rx_reserve_used) < 0)
+ atomic_inc(&dev->rx_reserve_used);
+}
+
+static inline void dev_drop_skb(struct sk_buff *skb)
+{
+ struct net_device *dev = skb->dev;
+ __kfree_skb(skb);
+ dev_unreserve(dev);
+}
+
#define HAVE_NETIF_RX 1
extern int netif_rx(struct sk_buff *skb);
extern int netif_rx_ni(struct sk_buff *skb);
diff -up --recursive 2.6.12.3.clean/include/net/sock.h
2.6.12.3/include/net/sock.h
--- 2.6.12.3.clean/include/net/sock.h 2005-07-15 17:18:57.000000000 -0400
+++ 2.6.12.3/include/net/sock.h 2005-08-05 21:53:09.000000000 -0400
@@ -382,6 +382,7 @@ enum sock_flags {
SOCK_NO_LARGESEND, /* whether to sent large segments or not */
SOCK_LOCALROUTE, /* route locally only, %SO_DONTROUTE setting */
SOCK_QUEUE_SHRUNK, /* write queue has been shrunk recently */
+ SOCK_MEMALLOC, /* protocol can use memalloc reserve */
};
static inline void sock_set_flag(struct sock *sk, enum sock_flags flag)
@@ -399,6 +400,11 @@ static inline int sock_flag(struct sock
return test_bit(flag, &sk->sk_flags);
}
+static inline int is_memalloc_sock(struct sock *sk)
+{
+ return sock_flag(sk, SOCK_MEMALLOC);
+}
+
static inline void sk_acceptq_removed(struct sock *sk)
{
sk->sk_ack_backlog--;
diff -up --recursive 2.6.12.3.clean/mm/page_alloc.c 2.6.12.3/mm/page_alloc.c
--- 2.6.12.3.clean/mm/page_alloc.c 2005-07-15 17:18:57.000000000 -0400
+++ 2.6.12.3/mm/page_alloc.c 2005-08-05 21:53:09.000000000 -0400
@@ -802,8 +802,8 @@ __alloc_pages(unsigned int __nocast gfp_
/* This allocation should allow future memory freeing. */
- if (((p->flags & PF_MEMALLOC) || unlikely(test_thread_flag(TIF_MEMDIE)))
- && !in_interrupt()) {
+ if ((((p->flags & PF_MEMALLOC) ||
unlikely(test_thread_flag(TIF_MEMDIE)))
+ && !in_interrupt()) || (gfp_mask & __GFP_MEMALLOC)) {
if (!(gfp_mask & __GFP_NOMEMALLOC)) {
/* go through the zonelist yet again, ignoring mins */
for (i = 0; (z = zones[i]) != NULL; i++) {
diff -up --recursive 2.6.12.3.clean/net/ethernet/eth.c
2.6.12.3/net/ethernet/eth.c
--- 2.6.12.3.clean/net/ethernet/eth.c 2005-07-15 17:18:57.000000000 -0400
+++ 2.6.12.3/net/ethernet/eth.c 2005-08-06 02:32:02.000000000 -0400
@@ -281,6 +281,7 @@ void ether_setup(struct net_device *dev)
dev->mtu = 1500; /* eth_mtu */
dev->addr_len = ETH_ALEN;
dev->tx_queue_len = 1000; /* Ethernet wants good queues */
+ dev->rx_reserve = 50;
dev->flags = IFF_BROADCAST|IFF_MULTICAST;
memset(dev->broadcast,0xFF, ETH_ALEN);
diff -up --recursive 2.6.12.3.clean/net/ipv4/icmp.c 2.6.12.3/net/ipv4/icmp.c
--- 2.6.12.3.clean/net/ipv4/icmp.c 2005-07-15 17:18:57.000000000 -0400
+++ 2.6.12.3/net/ipv4/icmp.c 2005-08-06 16:58:17.000000000 -0400
@@ -944,6 +944,11 @@ int icmp_rcv(struct sk_buff *skb)
default:;
}
+ if (dev_reserve_used(skb->dev)) {
+ dev_unreserve(skb->dev);
+ goto drop;
+ }
+
if (!pskb_pull(skb, sizeof(struct icmphdr)))
goto error;
diff -up --recursive 2.6.12.3.clean/net/ipv4/tcp_ipv4.c
2.6.12.3/net/ipv4/tcp_ipv4.c
--- 2.6.12.3.clean/net/ipv4/tcp_ipv4.c 2005-07-15 17:18:57.000000000 -0400
+++ 2.6.12.3/net/ipv4/tcp_ipv4.c 2005-08-06 16:59:15.000000000 -0400
@@ -1766,6 +1766,12 @@ int tcp_v4_rcv(struct sk_buff *skb)
if (!sk)
goto no_tcp_socket;
+ if (unlikely(dev_reserve_used(skb->dev))) {
+ dev_unreserve(skb->dev);
+ if (!is_memalloc_sock(sk))
+ goto discard_and_relse;
+ }
+
process:
if (sk->sk_state == TCP_TIME_WAIT)
goto do_time_wait;
diff -up --recursive 2.6.12.3.clean/net/ipv4/udp.c 2.6.12.3/net/ipv4/udp.c
--- 2.6.12.3.clean/net/ipv4/udp.c 2005-07-15 17:18:57.000000000 -0400
+++ 2.6.12.3/net/ipv4/udp.c 2005-08-06 17:12:20.000000000 -0400
@@ -1152,6 +1152,12 @@ int udp_rcv(struct sk_buff *skb)
sk = udp_v4_lookup(saddr, uh->source, daddr, uh->dest,
skb->dev->ifindex);
if (sk != NULL) {
+ if (unlikely(dev_reserve_used(skb->dev))) {
+ dev_unreserve(skb->dev);
+ if (!is_memalloc_sock(sk))
+ goto drop_noncritical;
+ }
+
int ret = udp_queue_rcv_skb(sk, skb);
sock_put(sk);
@@ -1163,6 +1169,7 @@ int udp_rcv(struct sk_buff *skb)
return 0;
}
+drop_noncritical:
if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
goto drop;
-
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