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authorMatt Mackall <mpm@selenic.com>2005-08-11 19:27:43 -0700
committerDavid S. Miller <davem@davemloft.net>2005-08-11 19:27:43 -0700
commit53fb95d3c14290fd6ee808b221e35493f096246f (patch)
tree146c31c79bbc66d8fde3afa5ae37a04b63041eba /net
parent2652076507b662fc88ba16c27b59c7bdd9ccd956 (diff)
downloadlinux-53fb95d3c14290fd6ee808b221e35493f096246f.tar.gz
[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 <mpm@selenic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/core/dev.c9
-rw-r--r--net/core/netpoll.c3
2 files changed, 8 insertions, 4 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index 52a3bf7ae177..faf59b02c4bf 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 c02a08da6d42..996787bca17f 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: