Commit a5b5bb9a authored by Ingo Molnar's avatar Ingo Molnar Committed by Linus Torvalds
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[PATCH] lockdep: annotate sk_locks 



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: default avatarIngo 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: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 0afffc72

include/net/sock.h

+10 −10
Original line number Diff line number Diff line
@@ -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;

net/core/sock.c

+88 −9
Original line number Diff line number Diff line
@@ -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);

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