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net: fix lock_sock_bh/unlock_sock_bh

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This new sock lock primitive was introduced to speedup some user context
socket manipulation. But it is unsafe to protect two threads, one using
regular lock_sock/release_sock, one using lock_sock_bh/unlock_sock_bh

This patch changes lock_sock_bh to be careful against 'owned' state.
If owned is found to be set, we must take the slow path.
lock_sock_bh() now returns a boolean to say if the slow path was taken,
and this boolean is used at unlock_sock_bh time to call the appropriate
unlock function.

After this change, BH are either disabled or enabled during the
lock_sock_bh/unlock_sock_bh protected section. This might be misleading,
so we rename these functions to lock_sock_fast()/unlock_sock_fast().

Reported-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Tested-by: Anton Blanchard <anton@samba.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2010-05-26 19:20:18 +00:00 • committed by David S. Miller
parent a56635a56f
commit 8a74ad60a5
5 changed files with 62 additions and 16 deletions
Download patch file Download diff file Expand all files Collapse all files

5
net/ipv6/udp.c
View file

@ -328,6 +328,7 @@ int udpv6_recvmsg(struct kiocb *iocb, struct sock *sk,
int err;
int is_udplite = IS_UDPLITE(sk);
int is_udp4;
bool slow;
if (addr_len)
*addr_len=sizeof(struct sockaddr_in6);
@ -424,7 +425,7 @@ out:
return err;
csum_copy_err:
lock_sock_bh(sk);
slow = lock_sock_fast(sk);
if (!skb_kill_datagram(sk, skb, flags)) {
if (is_udp4)
UDP_INC_STATS_USER(sock_net(sk),
@ -433,7 +434,7 @@ csum_copy_err:
UDP6_INC_STATS_USER(sock_net(sk),
UDP_MIB_INERRORS, is_udplite);
}
unlock_sock_bh(sk);
unlock_sock_fast(sk, slow);
if (flags & MSG_DONTWAIT)
return -EAGAIN;