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[PATCH] lockdep: annotate sk_locks

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Teach sk_lock semantics to the lock validator.  In the softirq path the
slock has mutex_trylock()+mutex_unlock() semantics, in the process context
sock_lock() case it has mutex_lock()/mutex_unlock() semantics.

Thus we treat sock_owned_by_user() flagged areas as an exclusion area too,
not just those areas covered by a held sk_lock.slock.

Effect on non-lockdep kernels: minimal, sk_lock_sock_init() has been turned
into an inline function.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Ingo Molnar 2006-07-03 00:25:35 -07:00 committed by Linus Torvalds
parent 0afffc723c
commit a5b5bb9a05
2 changed files with 98 additions and 19 deletions
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20
include/net/sock.h
View file

@ -44,6 +44,7 @@
#include <linux/timer.h>
#include <linux/cache.h>
#include <linux/module.h>
#include <linux/lockdep.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h> /* struct sk_buff */
#include <linux/security.h>
@ -78,18 +79,17 @@ typedef struct {
spinlock_t slock;
struct sock_iocb *owner;
wait_queue_head_t wq;
/*
* We express the mutex-alike socket_lock semantics
* to the lock validator by explicitly managing
* the slock as a lock variant (in addition to
* the slock itself):
*/
#ifdef CONFIG_DEBUG_LOCK_ALLOC
struct lockdep_map dep_map;
#endif
} socket_lock_t;
extern struct lock_class_key af_family_keys[AF_MAX];
#define sock_lock_init(__sk) \
do { spin_lock_init(&((__sk)->sk_lock.slock)); \
lockdep_set_class(&(__sk)->sk_lock.slock, \
af_family_keys + (__sk)->sk_family); \
(__sk)->sk_lock.owner = NULL; \
init_waitqueue_head(&((__sk)->sk_lock.wq)); \
} while(0)
struct sock;
struct proto;

97
net/core/sock.c
View file

@ -133,7 +133,42 @@
* Each address family might have different locking rules, so we have
* one slock key per address family:
*/
struct lock_class_key af_family_keys[AF_MAX];
static struct lock_class_key af_family_keys[AF_MAX];
static struct lock_class_key af_family_slock_keys[AF_MAX];
#ifdef CONFIG_DEBUG_LOCK_ALLOC
/*
* Make lock validator output more readable. (we pre-construct these
* strings build-time, so that runtime initialization of socket
* locks is fast):
*/
static const char *af_family_key_strings[AF_MAX+1] = {
"sk_lock-AF_UNSPEC", "sk_lock-AF_UNIX" , "sk_lock-AF_INET" ,
"sk_lock-AF_AX25" , "sk_lock-AF_IPX" , "sk_lock-AF_APPLETALK",
"sk_lock-AF_NETROM", "sk_lock-AF_BRIDGE" , "sk_lock-AF_ATMPVC" ,
"sk_lock-AF_X25" , "sk_lock-AF_INET6" , "sk_lock-AF_ROSE" ,
"sk_lock-AF_DECnet", "sk_lock-AF_NETBEUI" , "sk_lock-AF_SECURITY" ,
"sk_lock-AF_KEY" , "sk_lock-AF_NETLINK" , "sk_lock-AF_PACKET" ,
"sk_lock-AF_ASH" , "sk_lock-AF_ECONET" , "sk_lock-AF_ATMSVC" ,
"sk_lock-21" , "sk_lock-AF_SNA" , "sk_lock-AF_IRDA" ,
"sk_lock-AF_PPPOX" , "sk_lock-AF_WANPIPE" , "sk_lock-AF_LLC" ,
"sk_lock-27" , "sk_lock-28" , "sk_lock-29" ,
"sk_lock-AF_TIPC" , "sk_lock-AF_BLUETOOTH", "sk_lock-AF_MAX"
};
static const char *af_family_slock_key_strings[AF_MAX+1] = {
"slock-AF_UNSPEC", "slock-AF_UNIX" , "slock-AF_INET" ,
"slock-AF_AX25" , "slock-AF_IPX" , "slock-AF_APPLETALK",
"slock-AF_NETROM", "slock-AF_BRIDGE" , "slock-AF_ATMPVC" ,
"slock-AF_X25" , "slock-AF_INET6" , "slock-AF_ROSE" ,
"slock-AF_DECnet", "slock-AF_NETBEUI" , "slock-AF_SECURITY" ,
"slock-AF_KEY" , "slock-AF_NETLINK" , "slock-AF_PACKET" ,
"slock-AF_ASH" , "slock-AF_ECONET" , "slock-AF_ATMSVC" ,
"slock-21" , "slock-AF_SNA" , "slock-AF_IRDA" ,
"slock-AF_PPPOX" , "slock-AF_WANPIPE" , "slock-AF_LLC" ,
"slock-27" , "slock-28" , "slock-29" ,
"slock-AF_TIPC" , "slock-AF_BLUETOOTH", "slock-AF_MAX"
};
#endif
/*
* sk_callback_lock locking rules are per-address-family,
@ -249,9 +284,16 @@ int sk_receive_skb(struct sock *sk, struct sk_buff *skb)
skb->dev = NULL;
bh_lock_sock(sk);
if (!sock_owned_by_user(sk))
if (!sock_owned_by_user(sk)) {
/*
* trylock + unlock semantics:
*/
mutex_acquire(&sk->sk_lock.dep_map, 0, 1, _RET_IP_);
rc = sk->sk_backlog_rcv(sk, skb);
else
mutex_release(&sk->sk_lock.dep_map, 1, _RET_IP_);
} else
sk_add_backlog(sk, skb);
bh_unlock_sock(sk);
out:
@ -761,6 +803,33 @@ lenout:
return 0;
}
/*
* Initialize an sk_lock.
*
* (We also register the sk_lock with the lock validator.)
*/
static void inline sock_lock_init(struct sock *sk)
{
spin_lock_init(&sk->sk_lock.slock);
sk->sk_lock.owner = NULL;
init_waitqueue_head(&sk->sk_lock.wq);
/*
* Make sure we are not reinitializing a held lock:
*/
debug_check_no_locks_freed((void *)&sk->sk_lock, sizeof(sk->sk_lock));
/*
* Mark both the sk_lock and the sk_lock.slock as a
* per-address-family lock class:
*/
lockdep_set_class_and_name(&sk->sk_lock.slock,
af_family_slock_keys + sk->sk_family,
af_family_slock_key_strings[sk->sk_family]);
lockdep_init_map(&sk->sk_lock.dep_map,
af_family_key_strings[sk->sk_family],
af_family_keys + sk->sk_family);
}
/**
* sk_alloc - All socket objects are allocated here
* @family: protocol family
@ -1465,24 +1534,34 @@ void sock_init_data(struct socket *sock, struct sock *sk)
void fastcall lock_sock(struct sock *sk)
{
might_sleep();
spin_lock_bh(&(sk->sk_lock.slock));
spin_lock_bh(&sk->sk_lock.slock);
if (sk->sk_lock.owner)
__lock_sock(sk);
sk->sk_lock.owner = (void *)1;
spin_unlock_bh(&(sk->sk_lock.slock));
spin_unlock(&sk->sk_lock.slock);
/*
* The sk_lock has mutex_lock() semantics here:
*/
mutex_acquire(&sk->sk_lock.dep_map, 0, 0, _RET_IP_);
local_bh_enable();
}
EXPORT_SYMBOL(lock_sock);
void fastcall release_sock(struct sock *sk)
{
spin_lock_bh(&(sk->sk_lock.slock));
/*
* The sk_lock has mutex_unlock() semantics:
*/
mutex_release(&sk->sk_lock.dep_map, 1, _RET_IP_);
spin_lock_bh(&sk->sk_lock.slock);
if (sk->sk_backlog.tail)
__release_sock(sk);
sk->sk_lock.owner = NULL;
if (waitqueue_active(&(sk->sk_lock.wq)))
wake_up(&(sk->sk_lock.wq));
spin_unlock_bh(&(sk->sk_lock.slock));
if (waitqueue_active(&sk->sk_lock.wq))
wake_up(&sk->sk_lock.wq);
spin_unlock_bh(&sk->sk_lock.slock);
}
EXPORT_SYMBOL(release_sock);