[PATCH 0/2] Clean up owner field in sock_lock_t

[PATCH 0/2] Clean up owner field in sock_lock_t

[John Heffner]

I don't know why the owner field is a (struct sock_iocb *).  I'm assuming
it's historical.  Can someone check this out?  Did I miss some alternate
usage?

These patches are against net-2.6.24.

[PATCH 1/2] [NET] Cleanup: Use sock_owned_by_user() macro

[John Heffner]

Changes asserts in sunrpc to use sock_owned_by_user() macro instead of
referencing sock_lock.owner directly.

Signed-off-by: John Heffner <jheffner@psc.edu>
---
 net/sunrpc/svcsock.c  |    2 +-
 net/sunrpc/xprtsock.c |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index ed17a50..3a95612 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -104,7 +104,7 @@ static struct lock_class_key svc_slock_key[2];
 static inline void svc_reclassify_socket(struct socket *sock)
 {
 	struct sock *sk = sock->sk;
-	BUG_ON(sk->sk_lock.owner != NULL);
+	BUG_ON(sock_owned_by_user(sk));
 	switch (sk->sk_family) {
 	case AF_INET:
 		sock_lock_init_class_and_name(sk, "slock-AF_INET-NFSD",
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 4ae7eed..282efd4 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -1186,7 +1186,7 @@ static struct lock_class_key xs_slock_key[2];
 static inline void xs_reclassify_socket(struct socket *sock)
 {
 	struct sock *sk = sock->sk;
-	BUG_ON(sk->sk_lock.owner != NULL);
+	BUG_ON(sock_owned_by_user(sk));
 	switch (sk->sk_family) {
 	case AF_INET:
 		sock_lock_init_class_and_name(sk, "slock-AF_INET-NFS",
-- 
1.5.3.rc7.30.g947ad2

[PATCH 2/2] [NET] Change type of owner in sock_lock_t to int, rename

[John Heffner]

The type of owner in sock_lock_t is currently (struct sock_iocb *),
presumably for historical reasons.  It is never used as this type, only
tested as NULL or set to (void *)1.  For clarity, this changes it to type
int, and renames to owned, to avoid any possible type casting errors.

Signed-off-by: John Heffner <jheffner@psc.edu>
---
 include/net/sock.h |    7 +++----
 net/core/sock.c    |    6 +++---
 2 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index 802c670..5ed9fa4 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -76,10 +76,9 @@
  * between user contexts and software interrupt processing, whereas the
  * mini-semaphore synchronizes multiple users amongst themselves.
  */
-struct sock_iocb;
 typedef struct {
 	spinlock_t		slock;
-	struct sock_iocb	*owner;
+	int			owned;
 	wait_queue_head_t	wq;
 	/*
 	 * We express the mutex-alike socket_lock semantics
@@ -737,7 +736,7 @@ static inline int sk_stream_wmem_schedule(struct sock *sk, int size)
  * Since ~2.3.5 it is also exclusive sleep lock serializing
  * accesses from user process context.
  */
-#define sock_owned_by_user(sk)	((sk)->sk_lock.owner)
+#define sock_owned_by_user(sk)	((sk)->sk_lock.owned)
 
 /*
  * Macro so as to not evaluate some arguments when
@@ -748,7 +747,7 @@ static inline int sk_stream_wmem_schedule(struct sock *sk, int size)
  */
 #define sock_lock_init_class_and_name(sk, sname, skey, name, key) 	\
 do {									\
-	sk->sk_lock.owner = NULL;					\
+	sk->sk_lock.owned = 0;					\
 	init_waitqueue_head(&sk->sk_lock.wq);				\
 	spin_lock_init(&(sk)->sk_lock.slock);				\
 	debug_check_no_locks_freed((void *)&(sk)->sk_lock,		\
diff --git a/net/core/sock.c b/net/core/sock.c
index cfed7d4..edbc562 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1575,9 +1575,9 @@ void fastcall lock_sock_nested(struct sock *sk, int subclass)
 {
 	might_sleep();
 	spin_lock_bh(&sk->sk_lock.slock);
-	if (sk->sk_lock.owner)
+	if (sk->sk_lock.owned)
 		__lock_sock(sk);
-	sk->sk_lock.owner = (void *)1;
+	sk->sk_lock.owned = 1;
 	spin_unlock(&sk->sk_lock.slock);
 	/*
 	 * The sk_lock has mutex_lock() semantics here:
@@ -1598,7 +1598,7 @@ void fastcall release_sock(struct sock *sk)
 	spin_lock_bh(&sk->sk_lock.slock);
 	if (sk->sk_backlog.tail)
 		__release_sock(sk);
-	sk->sk_lock.owner = NULL;
+	sk->sk_lock.owned = 0;
 	if (waitqueue_active(&sk->sk_lock.wq))
 		wake_up(&sk->sk_lock.wq);
 	spin_unlock_bh(&sk->sk_lock.slock);
-- 
1.5.3.rc7.30.g947ad2

Re: [PATCH 0/2] Clean up owner field in sock_lock_t

[David Miller]

From: John Heffner <jheffner@psc.edu>
Date: Tue, 11 Sep 2007 14:01:31 -0400

> I don't know why the owner field is a (struct sock_iocb *).  I'm assuming
> it's historical.  Can someone check this out?  Did I miss some alternate
> usage?

AIO used it somehow in net/socket.c and I believe there was some
intention to access this sock_iocb deeper in the call chain.

None of that materialized of course :)

> These patches are against net-2.6.24.

Thanks a lot, I'll add these patches.