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Message-Id: <1254406141-16445-1-git-send-email-sjayaraman@suse.de>
Date: Thu, 1 Oct 2009 19:39:01 +0530
From: Suresh Jayaraman <sjayaraman@...e.de>
To: Linus Torvalds <torvalds@...ux-foundation.org>,
Andrew Morton <akpm@...ux-foundation.org>,
linux-kernel@...r.kernel.org, linux-mm@...ck.org
Cc: netdev@...r.kernel.org, Neil Brown <neilb@...e.de>,
Miklos Szeredi <mszeredi@...e.cz>, Wouter Verhelst <w@...r.be>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
trond.myklebust@....uio.no, Suresh Jayaraman <sjayaraman@...e.de>
Subject: [PATCH 22/31] netvm: skb processing
From: Peter Zijlstra <a.p.zijlstra@...llo.nl>
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@...llo.nl>
Signed-off-by: Suresh Jayaraman <sjayaraman@...e.de>
---
include/net/sock.h | 5 ++++
net/core/dev.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++-----
net/core/sock.c | 16 ++++++++++++++
3 files changed, 73 insertions(+), 5 deletions(-)
Index: mmotm/include/net/sock.h
===================================================================
--- mmotm.orig/include/net/sock.h
+++ mmotm/include/net/sock.h
@@ -619,8 +619,13 @@ static inline void sk_add_backlog(struct
skb->next = NULL;
}
+extern int __sk_backlog_rcv(struct sock *sk, struct sk_buff *skb);
+
static inline int sk_backlog_rcv(struct sock *sk, struct sk_buff *skb)
{
+ if (skb_emergency(skb))
+ return __sk_backlog_rcv(sk, skb);
+
return sk->sk_backlog_rcv(sk, skb);
}
Index: mmotm/net/core/dev.c
===================================================================
--- mmotm.orig/net/core/dev.c
+++ mmotm/net/core/dev.c
@@ -2225,6 +2225,30 @@ void netif_nit_deliver(struct sk_buff *s
rcu_read_unlock();
}
+/*
+ * Filter the protocols for which the reserves are adequate.
+ *
+ * Before adding a protocol make sure that it is either covered by the existing
+ * reserves, or add reserves covering the memory need of the new protocol's
+ * packet processing.
+ */
+static int skb_emergency_protocol(struct sk_buff *skb)
+{
+ 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:
+ return 0;
+ }
+
+ return 1;
+}
+
/**
* netif_receive_skb - process receive buffer from network
* @skb: buffer to process
@@ -2247,13 +2271,26 @@ int netif_receive_skb(struct sk_buff *sk
struct net_device *null_or_orig;
int ret = NET_RX_DROP;
__be16 type;
+ unsigned long pflags = current->flags;
if (skb->vlan_tci && vlan_hwaccel_do_receive(skb))
return NET_RX_SUCCESS;
+ /* Emergency skb are special, they should
+ * - be delivered to SOCK_MEMALLOC 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 (netpoll_receive_skb(skb))
- return NET_RX_DROP;
+ goto out;
if (!skb->tstamp.tv64)
net_timestamp(skb);
@@ -2287,6 +2324,9 @@ 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 == null_or_orig || ptype->dev == skb->dev ||
ptype->dev == orig_dev) {
@@ -2296,19 +2336,23 @@ int netif_receive_skb(struct sk_buff *sk
}
}
+skip_taps:
#ifdef CONFIG_NET_CLS_ACT
skb = handle_ing(skb, &pt_prev, &ret, orig_dev);
if (!skb)
- goto out;
+ goto unlock;
ncls:
#endif
+ if (!skb_emergency_protocol(skb))
+ goto drop;
+
skb = handle_bridge(skb, &pt_prev, &ret, orig_dev);
if (!skb)
- goto out;
+ goto unlock;
skb = handle_macvlan(skb, &pt_prev, &ret, orig_dev);
if (!skb)
- goto out;
+ goto unlock;
type = skb->protocol;
list_for_each_entry_rcu(ptype,
@@ -2325,6 +2369,7 @@ 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. :-)
@@ -2332,8 +2377,10 @@ ncls:
ret = NET_RX_DROP;
}
-out:
+unlock:
rcu_read_unlock();
+out:
+ tsk_restore_flags(current, pflags, PF_MEMALLOC);
return ret;
}
Index: mmotm/net/core/sock.c
===================================================================
--- mmotm.orig/net/core/sock.c
+++ mmotm/net/core/sock.c
@@ -315,6 +315,22 @@ int sk_clear_memalloc(struct sock *sk)
return set;
}
EXPORT_SYMBOL_GPL(sk_clear_memalloc);
+
+int __sk_backlog_rcv(struct sock *sk, struct sk_buff *skb)
+{
+ int ret;
+ unsigned long pflags = current->flags;
+
+ /* these should have been dropped before queueing */
+ BUG_ON(!sk_has_memalloc(sk));
+
+ current->flags |= PF_MEMALLOC;
+ ret = sk->sk_backlog_rcv(sk, skb);
+ tsk_restore_flags(current, pflags, PF_MEMALLOC);
+
+ return ret;
+}
+EXPORT_SYMBOL(__sk_backlog_rcv);
#endif
static int sock_set_timeout(long *timeo_p, char __user *optval, int optlen)
--
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