diff options
author | Eric Dumazet <edumazet@google.com> | 2014-06-30 12:26:23 +0400 |
---|---|---|
committer | Jiri Slaby <jslaby@suse.cz> | 2014-07-29 18:56:59 +0400 |
commit | 8728b0c1932dada25f2d1ccfa1669b5b41fe7937 (patch) | |
tree | 0ff960bdea41c619a05eeaf3e44864e88440aa77 /include/net/sock.h | |
parent | 591b1e1bb40152e22cee757f493046a0ca946bf8 (diff) | |
download | linux-8728b0c1932dada25f2d1ccfa1669b5b41fe7937.tar.xz |
ipv4: irq safe sk_dst_[re]set() and ipv4_sk_update_pmtu() fix
[ Upstream commit 7f502361531e9eecb396cf99bdc9e9a59f7ebd7f ]
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>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Diffstat (limited to 'include/net/sock.h')
-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 dc84ec518ff5..def541a583de 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1789,9 +1789,11 @@ __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 @@ -1803,9 +1805,7 @@ __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); } extern struct dst_entry *__sk_dst_check(struct sock *sk, u32 cookie); |