From 4dc6dc7162c08b9965163c9ab3f9375d4adff2c7 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 15 Jul 2009 23:13:10 +0000 Subject: net: sock_copy() fixes Commit e912b1142be8f1e2c71c71001dc992c6e5eb2ec1 (net: sk_prot_alloc() should not blindly overwrite memory) took care of not zeroing whole new socket at allocation time. sock_copy() is another spot where we should be very careful. We should not set refcnt to a non null value, until we are sure other fields are correctly setup, or a lockless reader could catch this socket by mistake, while not fully (re)initialized. This patch puts sk_node & sk_refcnt to the very beginning of struct sock to ease sock_copy() & sk_prot_alloc() job. We add appropriate smp_wmb() before sk_refcnt initializations to match our RCU requirements (changes to sock keys should be committed to memory before sk_refcnt setting) Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- include/net/sock.h | 32 +++++++++++++++++++------------- 1 file changed, 19 insertions(+), 13 deletions(-) (limited to 'include') diff --git a/include/net/sock.h b/include/net/sock.h index 2c0da92..950409d 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -104,15 +104,15 @@ struct net; /** * struct sock_common - minimal network layer representation of sockets + * @skc_node: main hash linkage for various protocol lookup tables + * @skc_nulls_node: main hash linkage for UDP/UDP-Lite protocol + * @skc_refcnt: reference count + * @skc_hash: hash value used with various protocol lookup tables * @skc_family: network address family * @skc_state: Connection state * @skc_reuse: %SO_REUSEADDR setting * @skc_bound_dev_if: bound device index if != 0 - * @skc_node: main hash linkage for various protocol lookup tables - * @skc_nulls_node: main hash linkage for UDP/UDP-Lite protocol * @skc_bind_node: bind hash linkage for various protocol lookup tables - * @skc_refcnt: reference count - * @skc_hash: hash value used with various protocol lookup tables * @skc_prot: protocol handlers inside a network family * @skc_net: reference to the network namespace of this socket * @@ -120,17 +120,21 @@ struct net; * for struct sock and struct inet_timewait_sock. */ struct sock_common { - unsigned short skc_family; - volatile unsigned char skc_state; - unsigned char skc_reuse; - int skc_bound_dev_if; + /* + * first fields are not copied in sock_copy() + */ union { struct hlist_node skc_node; struct hlist_nulls_node skc_nulls_node; }; - struct hlist_node skc_bind_node; atomic_t skc_refcnt; + unsigned int skc_hash; + unsigned short skc_family; + volatile unsigned char skc_state; + unsigned char skc_reuse; + int skc_bound_dev_if; + struct hlist_node skc_bind_node; struct proto *skc_prot; #ifdef CONFIG_NET_NS struct net *skc_net; @@ -208,15 +212,17 @@ struct sock { * don't add nothing before this first member (__sk_common) --acme */ struct sock_common __sk_common; +#define sk_node __sk_common.skc_node +#define sk_nulls_node __sk_common.skc_nulls_node +#define sk_refcnt __sk_common.skc_refcnt + +#define sk_copy_start __sk_common.skc_hash +#define sk_hash __sk_common.skc_hash #define sk_family __sk_common.skc_family #define sk_state __sk_common.skc_state #define sk_reuse __sk_common.skc_reuse #define sk_bound_dev_if __sk_common.skc_bound_dev_if -#define sk_node __sk_common.skc_node -#define sk_nulls_node __sk_common.skc_nulls_node #define sk_bind_node __sk_common.skc_bind_node -#define sk_refcnt __sk_common.skc_refcnt -#define sk_hash __sk_common.skc_hash #define sk_prot __sk_common.skc_prot #define sk_net __sk_common.skc_net kmemcheck_bitfield_begin(flags); -- cgit v1.1