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netpoll: Fix RCU usage

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The use of RCU in netpoll is incorrect in a number of places:

1) The initial setting is lacking a write barrier.
2) The synchronize_rcu is in the wrong place.
3) Read barriers are missing.
4) Some places are even missing rcu_read_lock.
5) npinfo is zeroed after freeing.

This patch fixes those issues.  As most users are in BH context,
this also converts the RCU usage to the BH variant.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Herbert Xu
2010-06-10 16:12:44 +00:00
committed by David S. Miller
parent 36655042f9
commit de85d99eb7
2 changed files with 20 additions and 13 deletions
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13
include/linux/netpoll.h
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@ -57,12 +57,15 @@ void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb);
#ifdef CONFIG_NETPOLL
static inline bool netpoll_rx(struct sk_buff *skb)
{
struct netpoll_info *npinfo = skb->dev->npinfo;
struct netpoll_info *npinfo;
unsigned long flags;
bool ret = false;
rcu_read_lock_bh();
npinfo = rcu_dereference(skb->dev->npinfo);
if (!npinfo || (list_empty(&npinfo->rx_np) && !npinfo->rx_flags))
return false;
goto out;
spin_lock_irqsave(&npinfo->rx_lock, flags);
/* check rx_flags again with the lock held */
@ -70,12 +73,14 @@ static inline bool netpoll_rx(struct sk_buff *skb)
ret = true;
spin_unlock_irqrestore(&npinfo->rx_lock, flags);
out:
rcu_read_unlock_bh();
return ret;
}
static inline int netpoll_rx_on(struct sk_buff *skb)
{
struct netpoll_info *npinfo = skb->dev->npinfo;
struct netpoll_info *npinfo = rcu_dereference(skb->dev->npinfo);
return npinfo && (!list_empty(&npinfo->rx_np) || npinfo->rx_flags);
}
@ -91,7 +96,6 @@ static inline void *netpoll_poll_lock(struct napi_struct *napi)
{
struct net_device *dev = napi->dev;
rcu_read_lock(); /* deal with race on ->npinfo */
if (dev && dev->npinfo) {
spin_lock(&napi->poll_lock);
napi->poll_owner = smp_processor_id();
@ -108,7 +112,6 @@ static inline void netpoll_poll_unlock(void *have)
napi->poll_owner = -1;
spin_unlock(&napi->poll_lock);
}
rcu_read_unlock();
}
#else