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| author |   Eric Dumazet <eric.dumazet@gmail.com> | 2012-07-31 01:08:23 +0000 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2012-07-31 14:41:38 -0700 |
| commit | 54764bb647b2e847c512acf8d443df965da35000 (patch) | |
| tree | 3918f6f42679d0ebdcef230f28285f99d178be62 /include/net | |
| parent | bridge: make port attributes const (diff) | |
| download | linux-dev-54764bb647b2e847c512acf8d443df965da35000.tar.xz linux-dev-54764bb647b2e847c512acf8d443df965da35000.zip | |
ipv4: Restore old dst_free() behavior.
commit 404e0a8b6a55 (net: ipv4: fix RCU races on dst refcounts) tried
to solve a race but added a problem at device/fib dismantle time :
We really want to call dst_free() as soon as possible, even if sockets
still have dst in their cache.
dst_release() calls in free_fib_info_rcu() are not welcomed.
Root of the problem was that now we also cache output routes (in
nh_rth_output), we must use call_rcu() instead of call_rcu_bh() in
rt_free(), because output route lookups are done in process context.
Based on feedback and initial patch from David Miller (adding another
call_rcu_bh() call in fib, but it appears it was not the right fix)
I left the inet_sk_rx_dst_set() helper and added __rcu attributes
to nh_rth_output and nh_rth_input to better document what is going on in
this code.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net')
| -rw-r--r-- | include/net/dst.h | 7 | ||||
| -rw-r--r-- | include/net/inet_sock.h | 10 | ||||
| -rw-r--r-- | include/net/ip_fib.h | 4 |
3 files changed, 11 insertions, 10 deletions
diff --git a/include/net/dst.h b/include/net/dst.h index 31a9fd39edb6..baf597890064 100644 --- a/include/net/dst.h +++ b/include/net/dst.h @@ -61,7 +61,6 @@ struct dst_entry { #define DST_NOPEER 0x0040 #define DST_FAKE_RTABLE 0x0080 #define DST_XFRM_TUNNEL 0x0100 -#define DST_RCU_FREE 0x0200 unsigned short pending_confirm; @@ -383,6 +382,12 @@ static inline void dst_free(struct dst_entry *dst) __dst_free(dst); } +static inline void dst_rcu_free(struct rcu_head *head) +{ + struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head); + dst_free(dst); +} + static inline void dst_confirm(struct dst_entry *dst) { dst->pending_confirm = 1; diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h index e3fd34c83ac9..83b567fe1941 100644 --- a/include/net/inet_sock.h +++ b/include/net/inet_sock.h @@ -253,13 +253,9 @@ static inline void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb { struct dst_entry *dst = skb_dst(skb); - if (atomic_inc_not_zero(&dst->__refcnt)) { - if (!(dst->flags & DST_RCU_FREE)) - dst->flags |= DST_RCU_FREE; - - sk->sk_rx_dst = dst; - inet_sk(sk)->rx_dst_ifindex = skb->skb_iif; - } + dst_hold(dst); + sk->sk_rx_dst = dst; + inet_sk(sk)->rx_dst_ifindex = skb->skb_iif; } #endif /* _INET_SOCK_H */ diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h index e69c3a47153d..e521a03515b1 100644 --- a/include/net/ip_fib.h +++ b/include/net/ip_fib.h @@ -81,8 +81,8 @@ struct fib_nh { __be32 nh_gw; __be32 nh_saddr; int nh_saddr_genid; - struct rtable *nh_rth_output; - struct rtable *nh_rth_input; + struct rtable __rcu *nh_rth_output; + struct rtable __rcu *nh_rth_input; struct fnhe_hash_bucket *nh_exceptions; }; |