Commit fbeec2e1 authored by Jeff Moyer's avatar Jeff Moyer Committed by David S. Miller
Browse files

[NETPOLL]: allow multiple netpoll_clients to register against one interface 



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.

Signed-off-by: default avatarJeff Moyer <jmoyer@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 115c1d6e

include/linux/netpoll.h

+12 −3
Original line number Diff line number Diff line
@@ -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)

net/core/netpoll.c

+29 −10
Original line number Diff line number Diff line
@@ -349,11 +349,15 @@ static void arp_reply(struct sk_buff *skb) 
	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;

}

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