Messages in this thread Patches in this message | | | From | Duncan Sands <> | Subject | [PATCH] UP locking fix for net/socket.c | Date | Thu, 31 Oct 2002 12:57:20 +0100 |
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This race occurs on UP (not SMP) systems. socket.c must not continue using net_family after sock_unregister(net_family) has returned. Here is a scenario for this to occur: go to sleep in the following call:
if ((i = net_families[family]->create(sock, protocol)) < 0)
While sleeping, a task calls sock_unregister(family), which succeeds since on UP there is currently no locking of any kind.
Duncan.
Patches against 2.4.19 and 2.5.45 attached. 2.4.19 patch:
--- linux/net/socket.c.orig 2002-08-03 02:39:46.000000000 +0200 +++ linux/net/socket.c 2002-10-31 09:16:50.000000000 +0100 @@ -132,7 +132,6 @@ static struct net_proto_family *net_families[NPROTO]; -#ifdef CONFIG_SMP static atomic_t net_family_lockct = ATOMIC_INIT(0); static spinlock_t net_family_lock = SPIN_LOCK_UNLOCKED; @@ -170,13 +169,6 @@ atomic_dec(&net_family_lockct); } -#else -#define net_family_write_lock() do { } while(0) -#define net_family_write_unlock() do { } while(0) -#define net_family_read_lock() do { } while(0) -#define net_family_read_unlock() do { } while(0) -#endif - /* * Statistics counters of the socket lists--- Yield/net/socket.c.orig 2002-10-31 09:10:07.000000000 +0100 +++ Yield/net/socket.c 2002-10-31 09:13:48.000000000 +0100 @@ -138,7 +138,6 @@ static struct net_proto_family *net_families[NPROTO]; -#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT) static atomic_t net_family_lockct = ATOMIC_INIT(0); static spinlock_t net_family_lock = SPIN_LOCK_UNLOCKED; @@ -175,13 +174,6 @@ atomic_dec(&net_family_lockct); } -#else -#define net_family_write_lock() do { } while(0) -#define net_family_write_unlock() do { } while(0) -#define net_family_read_lock() do { } while(0) -#define net_family_read_unlock() do { } while(0) -#endif - /* * Statistics counters of the socket lists--- linux/net/socket.c.orig 2002-08-03 02:39:46.000000000 +0200 +++ linux/net/socket.c 2002-10-31 09:16:50.000000000 +0100 @@ -132,7 +132,6 @@ static struct net_proto_family *net_families[NPROTO]; -#ifdef CONFIG_SMP static atomic_t net_family_lockct = ATOMIC_INIT(0); static spinlock_t net_family_lock = SPIN_LOCK_UNLOCKED; @@ -170,13 +169,6 @@ atomic_dec(&net_family_lockct); } -#else -#define net_family_write_lock() do { } while(0) -#define net_family_write_unlock() do { } while(0) -#define net_family_read_lock() do { } while(0) -#define net_family_read_unlock() do { } while(0) -#endif - /* * Statistics counters of the socket lists | |