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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
parent2652076507b662fc88ba16c27b59c7bdd9ccd956 (diff)
[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>
-rw-r--r--include/linux/netpoll.h19
-rw-r--r--net/core/dev.c9
-rw-r--r--net/core/netpoll.c3
3 files changed, 21 insertions, 10 deletions
diff --git a/include/linux/netpoll.h b/include/linux/netpoll.h
index be68d94b03d5..5ade54a78dbb 100644
--- a/include/linux/netpoll.h
+++ b/include/linux/netpoll.h
@@ -9,6 +9,7 @@
#include <linux/netdevice.h>
#include <linux/interrupt.h>
+#include <linux/rcupdate.h>
#include <linux/list.h>
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 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: