Hi,
This patch provides support for registering multiple netpoll clients to the
same network device. Only one of these clients may register an rx_hook,
however. In practice, this restriction has not been problematic. It is
worth mentioning, though, that the current design can be easily extended to
allow for the registration of multiple rx_hooks.
The basic idea of the patch is that the rx_np pointer in the netpoll_info
structure points to the struct netpoll that has rx_hook filled in. Aside
from this one case, there is no need for a pointer from the struct
net_device to an individual struct netpoll.
A lock is introduced to protect the setting and clearing of the np_rx
pointer. The pointer will only be cleared upon netpoll client module
removal, and the lock should be uncontested.
-Jeff
Signed-off-by: Jeff Moyer <[email protected]>
---
--- linux-2.6.12/net/core/netpoll.c.orig 2005-06-22 20:13:21.823259533 -0400
+++ linux-2.6.12/net/core/netpoll.c 2005-06-22 20:13:33.304353028 -0400
@@ -349,11 +349,15 @@ static void arp_reply(struct sk_buff *sk
unsigned char *arp_ptr;
int size, type = ARPOP_REPLY, ptype = ETH_P_ARP;
u32 sip, tip;
+ unsigned long flags;
struct sk_buff *send_skb;
struct netpoll *np = NULL;
- if (npinfo)
- np = npinfo->np;
+ spin_lock_irqsave(&npinfo->rx_lock, flags);
+ if (npinfo->rx_np && npinfo->rx_np->dev == skb->dev)
+ np = npinfo->rx_np;
+ spin_unlock_irqrestore(&npinfo->rx_lock, flags);
+
if (!np)
return;
@@ -436,9 +440,9 @@ int __netpoll_rx(struct sk_buff *skb)
int proto, len, ulen;
struct iphdr *iph;
struct udphdr *uh;
- struct netpoll *np = skb->dev->npinfo->np;
+ struct netpoll *np = skb->dev->npinfo->rx_np;
- if (!np->rx_hook)
+ if (!np)
goto out;
if (skb->dev->type != ARPHRD_ETHER)
goto out;
@@ -619,6 +623,7 @@ int netpoll_setup(struct netpoll *np)
struct net_device *ndev = NULL;
struct in_device *in_dev;
struct netpoll_info *npinfo;
+ unsigned long flags;
if (np->dev_name)
ndev = dev_get_by_name(np->dev_name);
@@ -634,9 +639,10 @@ int netpoll_setup(struct netpoll *np)
if (!npinfo)
goto release;
- npinfo->np = NULL;
+ npinfo->rx_np = NULL;
npinfo->poll_lock = SPIN_LOCK_UNLOCKED;
npinfo->poll_owner = -1;
+ npinfo->rx_lock = SPIN_LOCK_UNLOCKED;
} else
npinfo = ndev->npinfo;
@@ -706,9 +712,13 @@ int netpoll_setup(struct netpoll *np)
np->name, HIPQUAD(np->local_ip));
}
- if(np->rx_hook)
- npinfo->rx_flags = NETPOLL_RX_ENABLED;
- npinfo->np = np;
+ if (np->rx_hook) {
+ spin_lock_irqsave(&npinfo->rx_lock, flags);
+ npinfo->rx_flags |= NETPOLL_RX_ENABLED;
+ npinfo->rx_np = np;
+ spin_unlock_irqrestore(&npinfo->rx_lock, flags);
+ }
+ /* last thing to do is link it to the net device structure */
ndev->npinfo = npinfo;
return 0;
@@ -723,11 +733,20 @@ int netpoll_setup(struct netpoll *np)
void netpoll_cleanup(struct netpoll *np)
{
+ struct netpoll_info *npinfo;
+ unsigned long flags;
+
if (np->dev) {
- if (np->dev->npinfo)
- np->dev->npinfo->np = NULL;
+ npinfo = np->dev->npinfo;
+ if (npinfo && npinfo->rx_np == np) {
+ spin_lock_irqsave(&npinfo->rx_lock, flags);
+ npinfo->rx_np = NULL;
+ npinfo->rx_flags &= ~NETPOLL_RX_ENABLED;
+ spin_unlock_irqrestore(&npinfo->rx_lock, flags);
+ }
dev_put(np->dev);
}
+
np->dev = NULL;
}
--- linux-2.6.12/include/linux/netpoll.h.orig 2005-06-22 20:11:59.119992646 -0400
+++ linux-2.6.12/include/linux/netpoll.h 2005-06-22 20:13:33.306352696 -0400
@@ -27,7 +27,8 @@ struct netpoll_info {
spinlock_t poll_lock;
int poll_owner;
int rx_flags;
- struct netpoll *np;
+ spinlock_t rx_lock;
+ struct netpoll *rx_np; /* netpoll that registered an rx_hook */
};
void netpoll_poll(struct netpoll *np);
@@ -44,11 +45,19 @@ void netpoll_queue(struct sk_buff *skb);
static inline int netpoll_rx(struct sk_buff *skb)
{
struct netpoll_info *npinfo = skb->dev->npinfo;
+ unsigned long flags;
+ int ret = 0;
- if (!npinfo || !npinfo->rx_flags)
+ if (!npinfo || (!npinfo->rx_np && !npinfo->rx_flags))
return 0;
- return npinfo->np && __netpoll_rx(skb);
+ spin_lock_irqsave(&npinfo->rx_lock, flags);
+ /* check rx_flags again with the lock held */
+ if (npinfo->rx_flags && __netpoll_rx(skb))
+ ret = 1;
+ spin_unlock_irqrestore(&npinfo->rx_lock, flags);
+
+ return ret;
}
static inline void netpoll_poll_lock(struct net_device *dev)
-
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