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| author |   Herbert Xu <herbert@gondor.apana.org.au> | 2010-06-10 16:12:44 +0000 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2010-06-15 10:58:38 -0700 |
| commit | de85d99eb7b595f6751550184b94c1e2f74a828b (patch) | |
| tree | 950eea4329bfb2b5d94f2e242a86c36cf1fd49fc /net | |
| parent | bridge: Remove redundant npinfo NULL setting (diff) | |
| download | linux-dev-de85d99eb7b595f6751550184b94c1e2f74a828b.tar.xz linux-dev-de85d99eb7b595f6751550184b94c1e2f74a828b.zip | |
netpoll: Fix RCU usage
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>
Diffstat (limited to 'net')
| -rw-r--r-- | net/core/netpoll.c | 20 |
1 files changed, 12 insertions, 8 deletions
diff --git a/net/core/netpoll.c b/net/core/netpoll.c index 19ff66079f76..e9ab4f0c454c 100644 --- a/net/core/netpoll.c +++ b/net/core/netpoll.c @@ -261,6 +261,7 @@ void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb) unsigned long tries; struct net_device *dev = np->dev; const struct net_device_ops *ops = dev->netdev_ops; + /* It is up to the caller to keep npinfo alive. */ struct netpoll_info *npinfo = np->dev->npinfo; if (!npinfo || !netif_running(dev) || !netif_device_present(dev)) { @@ -810,10 +811,7 @@ int netpoll_setup(struct netpoll *np) refill_skbs(); /* last thing to do is link it to the net device structure */ - ndev->npinfo = npinfo; - - /* avoid racing with NAPI reading npinfo */ - synchronize_rcu(); + rcu_assign_pointer(ndev->npinfo, npinfo); return 0; @@ -857,6 +855,16 @@ void netpoll_cleanup(struct netpoll *np) if (atomic_dec_and_test(&npinfo->refcnt)) { const struct net_device_ops *ops; + + ops = np->dev->netdev_ops; + if (ops->ndo_netpoll_cleanup) + ops->ndo_netpoll_cleanup(np->dev); + + rcu_assign_pointer(np->dev->npinfo, NULL); + + /* avoid racing with NAPI reading npinfo */ + synchronize_rcu_bh(); + skb_queue_purge(&npinfo->arp_tx); skb_queue_purge(&npinfo->txq); cancel_rearming_delayed_work(&npinfo->tx_work); @@ -864,10 +872,6 @@ void netpoll_cleanup(struct netpoll *np) /* clean after last, unfinished work */ __skb_queue_purge(&npinfo->txq); kfree(npinfo); - ops = np->dev->netdev_ops; - if (ops->ndo_netpoll_cleanup) - ops->ndo_netpoll_cleanup(np->dev); - np->dev->npinfo = NULL; } } |