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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
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20
include/net/sock.h
View File

@ -1026,15 +1026,23 @@ extern void release_sock(struct sock *sk);
SINGLE_DEPTH_NESTING)
#define bh_unlock_sock(__sk) spin_unlock(&((__sk)->sk_lock.slock))
static inline void lock_sock_bh(struct sock *sk)
extern bool lock_sock_fast(struct sock *sk);
/**
* unlock_sock_fast - complement of lock_sock_fast
* @sk: socket
* @slow: slow mode
*
* fast unlock socket for user context.
* If slow mode is on, we call regular release_sock()
*/
static inline void unlock_sock_fast(struct sock *sk, bool slow)
{
spin_lock_bh(&sk->sk_lock.slock);
if (slow)
release_sock(sk);
else
spin_unlock_bh(&sk->sk_lock.slock);
}
static inline void unlock_sock_bh(struct sock *sk)
{
spin_unlock_bh(&sk->sk_lock.slock);
}
extern struct sock *sk_alloc(struct net *net, int family,
gfp_t priority,