Commit c564039f authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net: sk_wmem_alloc has initial value of one, not zero 



commit 2b85a34e
(net: No more expensive sock_hold()/sock_put() on each tx)
changed initial sk_wmem_alloc value.

Some protocols check sk_wmem_alloc value to determine if a timer
must delay socket deallocation. We must take care of the sk_wmem_alloc
value being one instead of zero when no write allocations are pending.

Reported by Ingo Molnar, and full diagnostic from David Miller.

This patch introduces three helpers to get read/write allocations
and a followup patch will use these helpers to report correct
write allocations to user.

Reported-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 1d4ac5d5

include/net/sock.h

+33 −0
Original line number Diff line number Diff line
@@ -1206,6 +1206,39 @@ static inline int skb_copy_to_page(struct sock *sk, char __user *from, 
	return 0;

}



/**

 * sk_wmem_alloc_get - returns write allocations

 * @sk: socket

 *

 * Returns sk_wmem_alloc minus initial offset of one

 */

static inline int sk_wmem_alloc_get(const struct sock *sk)

{

	return atomic_read(&sk->sk_wmem_alloc) - 1;

}



/**

 * sk_rmem_alloc_get - returns read allocations

 * @sk: socket

 *

 * Returns sk_rmem_alloc

 */

static inline int sk_rmem_alloc_get(const struct sock *sk)

{

	return atomic_read(&sk->sk_rmem_alloc);

}



/**

 * sk_has_allocations - check if allocations are outstanding

 * @sk: socket

 *

 * Returns true if socket has write or read allocations

 */

static inline int sk_has_allocations(const struct sock *sk)

{

	return sk_wmem_alloc_get(sk) || sk_rmem_alloc_get(sk);

}



/*

 * 	Queue a received datagram if it will fit. Stream and sequenced

 *	protocols can't normally use this as they need to fit buffers in

net/appletalk/ddp.c

+2 −4
Original line number Diff line number Diff line
@@ -162,8 +162,7 @@ static void atalk_destroy_timer(unsigned long data) 
{

	struct sock *sk = (struct sock *)data;



	if (atomic_read(&sk->sk_wmem_alloc) ||

	    atomic_read(&sk->sk_rmem_alloc)) {

	if (sk_has_allocations(sk)) {

		sk->sk_timer.expires = jiffies + SOCK_DESTROY_TIME;

		add_timer(&sk->sk_timer);

	} else
@@ -175,8 +174,7 @@ static inline void atalk_destroy_socket(struct sock *sk) 
	atalk_remove_socket(sk);

	skb_queue_purge(&sk->sk_receive_queue);



	if (atomic_read(&sk->sk_wmem_alloc) ||

	    atomic_read(&sk->sk_rmem_alloc)) {

	if (sk_has_allocations(sk)) {

		setup_timer(&sk->sk_timer, atalk_destroy_timer,

				(unsigned long)sk);

		sk->sk_timer.expires	= jiffies + SOCK_DESTROY_TIME;

net/ax25/af_ax25.c

+1 −2
Original line number Diff line number Diff line
@@ -330,8 +330,7 @@ void ax25_destroy_socket(ax25_cb *ax25) 
	}



	if (ax25->sk != NULL) {

		if (atomic_read(&ax25->sk->sk_wmem_alloc) ||

		    atomic_read(&ax25->sk->sk_rmem_alloc)) {

		if (sk_has_allocations(ax25->sk)) {

			/* Defer: outstanding buffers */

			setup_timer(&ax25->dtimer, ax25_destroy_timer,

					(unsigned long)ax25);

net/econet/af_econet.c

+2 −4
Original line number Diff line number Diff line
@@ -540,8 +540,7 @@ static void econet_destroy_timer(unsigned long data) 
{

	struct sock *sk=(struct sock *)data;



	if (!atomic_read(&sk->sk_wmem_alloc) &&

	    !atomic_read(&sk->sk_rmem_alloc)) {

	if (!sk_has_allocations(sk)) {

		sk_free(sk);

		return;

	}
@@ -579,8 +578,7 @@ static int econet_release(struct socket *sock) 


	skb_queue_purge(&sk->sk_receive_queue);



	if (atomic_read(&sk->sk_rmem_alloc) ||

	    atomic_read(&sk->sk_wmem_alloc)) {

	if (sk_has_allocations(sk)) {

		sk->sk_timer.data     = (unsigned long)sk;

		sk->sk_timer.expires  = jiffies + HZ;

		sk->sk_timer.function = econet_destroy_timer;

net/netrom/af_netrom.c

+1 −2
Original line number Diff line number Diff line
@@ -286,8 +286,7 @@ void nr_destroy_socket(struct sock *sk) 
		kfree_skb(skb);

	}



	if (atomic_read(&sk->sk_wmem_alloc) ||

	    atomic_read(&sk->sk_rmem_alloc)) {

	if (sk_has_allocations(sk)) {

		/* Defer: outstanding buffers */

		sk->sk_timer.function = nr_destroy_timer;

		sk->sk_timer.expires  = jiffies + 2 * HZ;

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