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| author | Eric Dumazet <edumazet@google.com> | 2014-06-30 10:26:23 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2014-07-01 08:40:58 +0200 |
| commit | 7f502361531e9eecb396cf99bdc9e9a59f7ebd7f (patch) | |
| tree | 6aeca5011b3a7aaedc275e8680407bc7e77b714d /include/net | |
| parent | powerpc: bpf: Fix the broken LD_VLAN_TAG_PRESENT test (diff) | |
| download | linux-7f502361531e9eecb396cf99bdc9e9a59f7ebd7f.tar.xz linux-7f502361531e9eecb396cf99bdc9e9a59f7ebd7f.zip | |
ipv4: irq safe sk_dst_[re]set() and ipv4_sk_update_pmtu() fix
We have two different ways to handle changes to sk->sk_dst
First way (used by TCP) assumes socket lock is owned by caller, and use
no extra lock : __sk_dst_set() & __sk_dst_reset()
Another way (used by UDP) uses sk_dst_lock because socket lock is not
always taken. Note that sk_dst_lock is not softirq safe.
These ways are not inter changeable for a given socket type.
ipv4_sk_update_pmtu(), added in linux-3.8, added a race, as it used
the socket lock as synchronization, but users might be UDP sockets.
Instead of converting sk_dst_lock to a softirq safe version, use xchg()
as we did for sk_rx_dst in commit e47eb5dfb296b ("udp: ipv4: do not use
sk_dst_lock from softirq context")
In a follow up patch, we probably can remove sk_dst_lock, as it is
only used in IPv6.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Fixes: 9cb3a50c5f63e ("ipv4: Invalidate the socket cached route on pmtu events if possible")
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net')
| -rw-r--r-- | include/net/sock.h | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/include/net/sock.h b/include/net/sock.h index 173cae485de1..c556fd9b05ac 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1768,9 +1768,11 @@ __sk_dst_set(struct sock *sk, struct dst_entry *dst) static inline void sk_dst_set(struct sock *sk, struct dst_entry *dst) { - spin_lock(&sk->sk_dst_lock); - __sk_dst_set(sk, dst); - spin_unlock(&sk->sk_dst_lock); + struct dst_entry *old_dst; + + sk_tx_queue_clear(sk); + old_dst = xchg(&sk->sk_dst_cache, dst); + dst_release(old_dst); } static inline void @@ -1782,9 +1784,7 @@ __sk_dst_reset(struct sock *sk) static inline void sk_dst_reset(struct sock *sk) { - spin_lock(&sk->sk_dst_lock); - __sk_dst_reset(sk); - spin_unlock(&sk->sk_dst_lock); + sk_dst_set(sk, NULL); } struct dst_entry *__sk_dst_check(struct sock *sk, u32 cookie); |