Messages in this thread Patch in this message | | | From | Jeff Moyer <> | Date | Wed, 22 Jun 2005 21:30:47 -0400 | Subject | [patch 3/3] netpoll: allow multiple netpoll_clients to register against one interface |
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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 <jmoyer@redhat.com> ---
--- 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) - 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/
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