lkml.org 
[lkml]   [2007]   [Feb]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH 19/29] netvm: skb processing
In order to make sure emergency packets receive all memory needed to proceed
ensure processing of emergency skbs happens under PF_MEMALLOC.

Use the (new) sk_backlog_rcv() wrapper to ensure this for backlog processing.

Skip taps, since those are user-space again.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
include/net/sock.h | 4 ++++
net/core/dev.c | 42 +++++++++++++++++++++++++++++++++++++-----
net/core/sock.c | 19 +++++++++++++++++++
3 files changed, 60 insertions(+), 5 deletions(-)
Index: linux-2.6-git/net/core/dev.c
===================================================================
--- linux-2.6-git.orig/net/core/dev.c 2007-02-14 12:16:03.000000000 +0100
+++ linux-2.6-git/net/core/dev.c 2007-02-14 12:28:33.000000000 +0100
@@ -1767,10 +1767,23 @@ int netif_receive_skb(struct sk_buff *sk
struct net_device *orig_dev;
int ret = NET_RX_DROP;
__be16 type;
+ unsigned long pflags = current->flags;
+
+ /* Emergency skb are special, they should
+ * - be delivered to SOCK_VMIO sockets only
+ * - stay away from userspace
+ * - have bounded memory usage
+ *
+ * Use PF_MEMALLOC as a poor mans memory pool - the grouping kind.
+ * This saves us from propagating the allocation context down to all
+ * allocation sites.
+ */
+ if (skb_emergency(skb))
+ current->flags |= PF_MEMALLOC;

/* if we've gotten here through NAPI, check netpoll */
if (skb->dev->poll && netpoll_rx(skb))
- return NET_RX_DROP;
+ goto out;

if (!skb->tstamp.off_sec)
net_timestamp(skb);
@@ -1781,7 +1794,7 @@ int netif_receive_skb(struct sk_buff *sk
orig_dev = skb_bond(skb);

if (!orig_dev)
- return NET_RX_DROP;
+ goto out;

__get_cpu_var(netdev_rx_stat).total++;

@@ -1799,6 +1812,9 @@ int netif_receive_skb(struct sk_buff *sk
}
#endif

+ if (skb_emergency(skb))
+ goto skip_taps;
+
list_for_each_entry_rcu(ptype, &ptype_all, list) {
if (!ptype->dev || ptype->dev == skb->dev) {
if (pt_prev)
@@ -1807,6 +1823,7 @@ int netif_receive_skb(struct sk_buff *sk
}
}

+skip_taps:
#ifdef CONFIG_NET_CLS_ACT
if (pt_prev) {
ret = deliver_skb(skb, pt_prev, orig_dev);
@@ -1819,15 +1836,27 @@ int netif_receive_skb(struct sk_buff *sk

if (ret == TC_ACT_SHOT || (ret == TC_ACT_STOLEN)) {
kfree_skb(skb);
- goto out;
+ goto unlock;
}

skb->tc_verd = 0;
ncls:
#endif

+ if (skb_emergency(skb))
+ switch(skb->protocol) {
+ case __constant_htons(ETH_P_ARP):
+ case __constant_htons(ETH_P_IP):
+ case __constant_htons(ETH_P_IPV6):
+ case __constant_htons(ETH_P_8021Q):
+ break;
+
+ default:
+ goto drop;
+ }
+
if (handle_bridge(&skb, &pt_prev, &ret, orig_dev))
- goto out;
+ goto unlock;

type = skb->protocol;
list_for_each_entry_rcu(ptype, &ptype_base[ntohs(type)&15], list) {
@@ -1842,6 +1871,7 @@ ncls:
if (pt_prev) {
ret = pt_prev->func(skb, skb->dev, pt_prev, orig_dev);
} else {
+drop:
kfree_skb(skb);
/* Jamal, now you will not able to escape explaining
* me how you were going to use this. :-)
@@ -1849,8 +1879,10 @@ ncls:
ret = NET_RX_DROP;
}

-out:
+unlock:
rcu_read_unlock();
+out:
+ current->flags = pflags;
return ret;
}

Index: linux-2.6-git/include/net/sock.h
===================================================================
--- linux-2.6-git.orig/include/net/sock.h 2007-02-14 12:32:03.000000000 +0100
+++ linux-2.6-git/include/net/sock.h 2007-02-14 12:32:37.000000000 +0100
@@ -510,10 +510,14 @@ static inline void sk_add_backlog(struct
skb->next = NULL;
}

+#ifndef CONFIG_NETVM
static inline int sk_backlog_rcv(struct sock *sk, struct sk_buff *skb)
{
return sk->sk_backlog_rcv(sk, skb);
}
+#else
+extern int sk_backlog_rcv(struct sock *sk, struct sk_buff *skb);
+#endif

#define sk_wait_event(__sk, __timeo, __condition) \
({ int rc; \
Index: linux-2.6-git/net/core/sock.c
===================================================================
--- linux-2.6-git.orig/net/core/sock.c 2007-02-14 12:32:07.000000000 +0100
+++ linux-2.6-git/net/core/sock.c 2007-02-14 12:37:11.000000000 +0100
@@ -332,6 +332,25 @@ int sk_clear_vmio(struct sock *sk)
}
EXPORT_SYMBOL_GPL(sk_clear_vmio);

+#ifdef CONFIG_NETVM
+int sk_backlog_rcv(struct sock *sk, struct sk_buff *skb)
+{
+ if (skb_emergency(skb)) {
+ int ret;
+ unsigned long pflags = current->flags;
+ /* these should have been dropped before queueing */
+ BUG_ON(!sk_has_vmio(sk));
+ current->flags |= PF_MEMALLOC;
+ ret = sk->sk_backlog_rcv(sk, skb);
+ current->flags = pflags;
+ return ret;
+ }
+
+ return sk->sk_backlog_rcv(sk, skb);
+}
+EXPORT_SYMBOL(sk_backlog_rcv);
+#endif
+
static int sock_set_timeout(long *timeo_p, char __user *optval, int optlen)
{
struct timeval tv;
--

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-02-21 16:13    [from the cache]
©2003-2011 Jasper Spaans