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Commit 16b304f3 authored by Pravin B Shelar's avatar Pravin B Shelar Committed by David S. Miller
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netlink: Eliminate kmalloc in netlink dump operation. 



Following patch stores struct netlink_callback in netlink_sock
to avoid allocating and freeing it on every netlink dump msg.
Only one dump operation is allowed for a given socket at a time
therefore we can safely convert cb pointer to cb struct inside
netlink_sock.

Signed-off-by: default avatarPravin B Shelar <pshelar@nicira.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent de98ac5e

net/netlink/af_netlink.c

+42 −55
Original line number Diff line number Diff line
@@ -595,7 +595,7 @@ static unsigned int netlink_poll(struct file *file, struct socket *sock, 
		 * for dumps is performed here. A dump is allowed to continue

		 * if at least half the ring is unused.

		 */

		while (nlk->cb != NULL && netlink_dump_space(nlk)) {

		while (nlk->cb_running && netlink_dump_space(nlk)) {

			err = netlink_dump(sk);

			if (err < 0) {

				sk->sk_err = err;
@@ -802,18 +802,6 @@ static void netlink_ring_set_copied(struct sock *sk, struct sk_buff *skb) 
#define netlink_mmap_sendmsg(sk, msg, dst_portid, dst_group, siocb)	0

#endif /* CONFIG_NETLINK_MMAP */



static void netlink_destroy_callback(struct netlink_callback *cb)

{

	kfree_skb(cb->skb);

	kfree(cb);

}



static void netlink_consume_callback(struct netlink_callback *cb)

{

	consume_skb(cb->skb);

	kfree(cb);

}



static void netlink_skb_destructor(struct sk_buff *skb)

{

#ifdef CONFIG_NETLINK_MMAP
@@ -872,12 +860,12 @@ static void netlink_sock_destruct(struct sock *sk) 
{

	struct netlink_sock *nlk = nlk_sk(sk);



	if (nlk->cb) {

		if (nlk->cb->done)

			nlk->cb->done(nlk->cb);

	if (nlk->cb_running) {

		if (nlk->cb.done)

			nlk->cb.done(&nlk->cb);



		module_put(nlk->cb->module);

		netlink_destroy_callback(nlk->cb);

		module_put(nlk->cb.module);

		kfree_skb(nlk->cb.skb);

	}



	skb_queue_purge(&sk->sk_receive_queue);
@@ -2350,7 +2338,8 @@ static int netlink_recvmsg(struct kiocb *kiocb, struct socket *sock, 


	skb_free_datagram(sk, skb);



	if (nlk->cb && atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf / 2) {

	if (nlk->cb_running &&

	    atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf / 2) {

		ret = netlink_dump(sk);

		if (ret) {

			sk->sk_err = ret;
@@ -2566,13 +2555,12 @@ static int netlink_dump(struct sock *sk) 
	int alloc_size;



	mutex_lock(nlk->cb_mutex);



	cb = nlk->cb;

	if (cb == NULL) {

	if (!nlk->cb_running) {

		err = -EINVAL;

		goto errout_skb;

	}



	cb = &nlk->cb;

	alloc_size = max_t(int, cb->min_dump_alloc, NLMSG_GOODSIZE);



	if (!netlink_rx_is_mmaped(sk) &&
@@ -2610,11 +2598,11 @@ static int netlink_dump(struct sock *sk) 


	if (cb->done)

		cb->done(cb);

	nlk->cb = NULL;

	mutex_unlock(nlk->cb_mutex);



	nlk->cb_running = false;

	mutex_unlock(nlk->cb_mutex);

	module_put(cb->module);

	netlink_consume_callback(cb);

	consume_skb(cb->skb);

	return 0;



errout_skb:
@@ -2632,59 +2620,51 @@ int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb, 
	struct netlink_sock *nlk;

	int ret;



	cb = kzalloc(sizeof(*cb), GFP_KERNEL);

	if (cb == NULL)

		return -ENOBUFS;



	/* Memory mapped dump requests need to be copied to avoid looping

	 * on the pending state in netlink_mmap_sendmsg() while the CB hold

	 * a reference to the skb.

	 */

	if (netlink_skb_is_mmaped(skb)) {

		skb = skb_copy(skb, GFP_KERNEL);

		if (skb == NULL) {

			kfree(cb);

		if (skb == NULL)

			return -ENOBUFS;

		}

	} else

		atomic_inc(&skb->users);



	cb->dump = control->dump;

	cb->done = control->done;

	cb->nlh = nlh;

	cb->data = control->data;

	cb->module = control->module;

	cb->min_dump_alloc = control->min_dump_alloc;

	cb->skb = skb;



	sk = netlink_lookup(sock_net(ssk), ssk->sk_protocol, NETLINK_CB(skb).portid);

	if (sk == NULL) {

		netlink_destroy_callback(cb);

		return -ECONNREFUSED;

		ret = -ECONNREFUSED;

		goto error_free;

	}

	nlk = nlk_sk(sk);



	nlk = nlk_sk(sk);

	mutex_lock(nlk->cb_mutex);

	/* A dump is in progress... */

	if (nlk->cb) {

		mutex_unlock(nlk->cb_mutex);

		netlink_destroy_callback(cb);

	if (nlk->cb_running) {

		ret = -EBUSY;

		goto out;

		goto error_unlock;

	}

	/* add reference of module which cb->dump belongs to */

	if (!try_module_get(cb->module)) {

		mutex_unlock(nlk->cb_mutex);

		netlink_destroy_callback(cb);

	if (!try_module_get(control->module)) {

		ret = -EPROTONOSUPPORT;

		goto out;

		goto error_unlock;

	}



	nlk->cb = cb;

	cb = &nlk->cb;

	memset(cb, 0, sizeof(*cb));

	cb->dump = control->dump;

	cb->done = control->done;

	cb->nlh = nlh;

	cb->data = control->data;

	cb->module = control->module;

	cb->min_dump_alloc = control->min_dump_alloc;

	cb->skb = skb;



	nlk->cb_running = true;



	mutex_unlock(nlk->cb_mutex);



	ret = netlink_dump(sk);

out:

	sock_put(sk);



	if (ret)
@@ -2694,6 +2674,13 @@ out: 
	 * signal not to send ACK even if it was requested.

	 */

	return -EINTR;



error_unlock:

	sock_put(sk);

	mutex_unlock(nlk->cb_mutex);

error_free:

	kfree_skb(skb);

	return ret;

}

EXPORT_SYMBOL(__netlink_dump_start);
@@ -2916,14 +2903,14 @@ static int netlink_seq_show(struct seq_file *seq, void *v) 
		struct sock *s = v;

		struct netlink_sock *nlk = nlk_sk(s);



		seq_printf(seq, "%pK %-3d %-6u %08x %-8d %-8d %pK %-8d %-8d %-8lu\n",

		seq_printf(seq, "%pK %-3d %-6u %08x %-8d %-8d %d %-8d %-8d %-8lu\n",

			   s,

			   s->sk_protocol,

			   nlk->portid,

			   nlk->groups ? (u32)nlk->groups[0] : 0,

			   sk_rmem_alloc_get(s),

			   sk_wmem_alloc_get(s),

			   nlk->cb,

			   nlk->cb_running,

			   atomic_read(&s->sk_refcnt),

			   atomic_read(&s->sk_drops),

			   sock_i_ino(s)

net/netlink/af_netlink.h

+2 −1
Original line number Diff line number Diff line
@@ -32,7 +32,8 @@ struct netlink_sock { 
	unsigned long		*groups;

	unsigned long		state;

	wait_queue_head_t	wait;

	struct netlink_callback	*cb;

	bool			cb_running;

	struct netlink_callback	cb;

	struct mutex		*cb_mutex;

	struct mutex		cb_def_mutex;

	void			(*netlink_rcv)(struct sk_buff *skb);