From 53fb95d3c14290fd6ee808b221e35493f096246f Mon Sep 17 00:00:00 2001 From: Matt Mackall Date: Thu, 11 Aug 2005 19:27:43 -0700 Subject: [PATCH] [NETPOLL]: fix initialization/NAPI race This fixes a race during initialization with the NAPI softirq processing by using an RCU approach. This race was discovered when refill_skbs() was added to the setup code. Signed-off-by: Matt Mackall Signed-off-by: David S. Miller --- include/linux/netpoll.h | 19 +++++++++++++------ net/core/dev.c | 9 +++++---- net/core/netpoll.c | 3 +++ 3 files changed, 21 insertions(+), 10 deletions(-) diff --git a/include/linux/netpoll.h b/include/linux/netpoll.h index be68d94b03d..5ade54a78db 100644 --- a/include/linux/netpoll.h +++ b/include/linux/netpoll.h @@ -9,6 +9,7 @@ #include #include +#include #include struct netpoll; @@ -61,25 +62,31 @@ static inline int netpoll_rx(struct sk_buff *skb) return ret; } -static inline void netpoll_poll_lock(struct net_device *dev) +static inline void *netpoll_poll_lock(struct net_device *dev) { + rcu_read_lock(); /* deal with race on ->npinfo */ if (dev->npinfo) { spin_lock(&dev->npinfo->poll_lock); dev->npinfo->poll_owner = smp_processor_id(); + return dev->npinfo; } + return NULL; } -static inline void netpoll_poll_unlock(struct net_device *dev) +static inline void netpoll_poll_unlock(void *have) { - if (dev->npinfo) { - dev->npinfo->poll_owner = -1; - spin_unlock(&dev->npinfo->poll_lock); + struct netpoll_info *npi = have; + + if (npi) { + npi->poll_owner = -1; + spin_unlock(&npi->poll_lock); } + rcu_read_unlock(); } #else #define netpoll_rx(a) 0 -#define netpoll_poll_lock(a) +#define netpoll_poll_lock(a) 0 #define netpoll_poll_unlock(a) #endif diff --git a/net/core/dev.c b/net/core/dev.c index 52a3bf7ae17..faf59b02c4b 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -1696,7 +1696,8 @@ static void net_rx_action(struct softirq_action *h) struct softnet_data *queue = &__get_cpu_var(softnet_data); unsigned long start_time = jiffies; int budget = netdev_budget; - + void *have; + local_irq_disable(); while (!list_empty(&queue->poll_list)) { @@ -1709,10 +1710,10 @@ static void net_rx_action(struct softirq_action *h) dev = list_entry(queue->poll_list.next, struct net_device, poll_list); - netpoll_poll_lock(dev); + have = netpoll_poll_lock(dev); if (dev->quota <= 0 || dev->poll(dev, &budget)) { - netpoll_poll_unlock(dev); + netpoll_poll_unlock(have); local_irq_disable(); list_del(&dev->poll_list); list_add_tail(&dev->poll_list, &queue->poll_list); @@ -1721,7 +1722,7 @@ static void net_rx_action(struct softirq_action *h) else dev->quota = dev->weight; } else { - netpoll_poll_unlock(dev); + netpoll_poll_unlock(have); dev_put(dev); local_irq_disable(); } diff --git a/net/core/netpoll.c b/net/core/netpoll.c index c02a08da6d4..996787bca17 100644 --- a/net/core/netpoll.c +++ b/net/core/netpoll.c @@ -732,6 +732,9 @@ int netpoll_setup(struct netpoll *np) /* last thing to do is link it to the net device structure */ ndev->npinfo = npinfo; + /* avoid racing with NAPI reading npinfo */ + synchronize_rcu(); + return 0; release: -- 2.41.0