From: Jeff Moyer This patch contains the updates necessary to fix the hangs in netconsole. This includes the changing of trapped to an atomic_t, and the addition of a netpoll_poll_lock. It also turns dev->netpoll_rx into a bitfield which is used to keep from running the networking code from the netpoll_poll call path. Signed-off-by: Jeff Moyer Signed-off-by: Matt Mackall Signed-off-by: Andrew Morton --- /dev/null | 0 25-akpm/net/core/netpoll.c | 35 +++++++++++++++++++++++++++-------- 2 files changed, 27 insertions(+), 8 deletions(-) diff -puN net/core/netpoll.c~netpoll-fix-up-trapped-logic net/core/netpoll.c --- 25/net/core/netpoll.c~netpoll-fix-up-trapped-logic Thu Aug 26 16:36:37 2004 +++ 25-akpm/net/core/netpoll.c Thu Aug 26 16:36:37 2004 @@ -38,7 +38,11 @@ static struct sk_buff *skbs; static spinlock_t rx_list_lock = SPIN_LOCK_UNLOCKED; static LIST_HEAD(rx_list); -static int trapped; +static atomic_t trapped; +spinlock_t netpoll_poll_lock = SPIN_LOCK_UNLOCKED; + +#define NETPOLL_RX_ENABLED 1 +#define NETPOLL_RX_DROP 2 #define MAX_SKB_SIZE \ (MAX_UDP_CHUNK + sizeof(struct udphdr) + \ @@ -70,6 +74,7 @@ void netpoll_poll(struct netpoll *np) * timeouts. Thus, we set our budget to a more reasonable value. */ int budget = 16; + unsigned long flags; if(!np->dev || !netif_running(np->dev) || !np->dev->poll_controller) return; @@ -78,9 +83,19 @@ void netpoll_poll(struct netpoll *np) np->dev->poll_controller(np->dev); /* If scheduling is stopped, tickle NAPI bits */ - if(trapped && np->dev->poll && - test_bit(__LINK_STATE_RX_SCHED, &np->dev->state)) + spin_lock_irqsave(&netpoll_poll_lock, flags); + if (np->dev->poll && + test_bit(__LINK_STATE_RX_SCHED, &np->dev->state)) { + np->dev->netpoll_rx |= NETPOLL_RX_DROP; + atomic_inc(&trapped); + np->dev->poll(np->dev, &budget); + + atomic_dec(&trapped); + np->dev->netpoll_rx &= ~NETPOLL_RX_DROP; + } + spin_unlock_irqrestore(&netpoll_poll_lock, flags); + zap_completion_queue(); } @@ -357,7 +372,8 @@ int netpoll_rx(struct sk_buff *skb) goto out; /* check if netpoll clients need ARP */ - if (skb->protocol == __constant_htons(ETH_P_ARP) && trapped) { + if (skb->protocol == __constant_htons(ETH_P_ARP) && + atomic_read(&trapped)) { arp_reply(skb); return 1; } @@ -420,7 +436,7 @@ int netpoll_rx(struct sk_buff *skb) spin_unlock_irqrestore(&rx_list_lock, flags); out: - return trapped; + return atomic_read(&trapped); } int netpoll_parse_options(struct netpoll *np, char *opt) @@ -613,7 +629,7 @@ int netpoll_setup(struct netpoll *np) if(np->rx_hook) { unsigned long flags; - np->dev->netpoll_rx = 1; + np->dev->netpoll_rx = NETPOLL_RX_ENABLED; spin_lock_irqsave(&rx_list_lock, flags); list_add(&np->rx_list, &rx_list); @@ -644,12 +660,15 @@ void netpoll_cleanup(struct netpoll *np) int netpoll_trap(void) { - return trapped; + return atomic_read(&trapped); } void netpoll_set_trap(int trap) { - trapped = trap; + if (trap) + atomic_inc(&trapped); + else + atomic_dec(&trapped); } EXPORT_SYMBOL(netpoll_set_trap); diff -L net/core/netpoll.c.locking -puN /dev/null /dev/null _