Commit 5c040eaf authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by Daniel Borkmann
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tcp: Add num_closed_socks to struct sock_reuseport. 



As noted in the following commit, a closed listener has to hold the
reference to the reuseport group for socket migration. This patch adds a
field (num_closed_socks) to struct sock_reuseport to manage closed sockets
within the same reuseport group. Moreover, this and the following commits
introduce some helper functions to split socks[] into two sections and keep
TCP_LISTEN and TCP_CLOSE sockets in each section. Like a double-ended
queue, we will place TCP_LISTEN sockets from the front and TCP_CLOSE
sockets from the end.

  TCP_LISTEN---------->       <-------TCP_CLOSE
  +---+---+  ---  +---+  ---  +---+  ---  +---+
  | 0 | 1 |  ...  | i |  ...  | j |  ...  | k |
  +---+---+  ---  +---+  ---  +---+  ---  +---+

  i = num_socks - 1
  j = max_socks - num_closed_socks
  k = max_socks - 1

This patch also extends reuseport_add_sock() and reuseport_grow() to
support num_closed_socks.

Signed-off-by: default avatarKuniyuki Iwashima <kuniyu@amazon.co.jp>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Acked-by: default avatarMartin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210612123224.12525-3-kuniyu@amazon.co.jp
parent f9ac779f

include/net/sock_reuseport.h

+3 −2
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ struct sock_reuseport { 


	u16			max_socks;		/* length of socks */

	u16			num_socks;		/* elements in socks */

	u16			num_closed_socks;	/* closed elements in socks */

	/* The last synq overflow event timestamp of this

	 * reuse->socks[] group.

	 */

net/core/sock_reuseport.c

+57 −18
Original line number Diff line number Diff line
@@ -18,6 +18,49 @@ DEFINE_SPINLOCK(reuseport_lock); 


static DEFINE_IDA(reuseport_ida);



static int reuseport_sock_index(struct sock *sk,

				const struct sock_reuseport *reuse,

				bool closed)

{

	int left, right;



	if (!closed) {

		left = 0;

		right = reuse->num_socks;

	} else {

		left = reuse->max_socks - reuse->num_closed_socks;

		right = reuse->max_socks;

	}



	for (; left < right; left++)

		if (reuse->socks[left] == sk)

			return left;

	return -1;

}



static void __reuseport_add_sock(struct sock *sk,

				 struct sock_reuseport *reuse)

{

	reuse->socks[reuse->num_socks] = sk;

	/* paired with smp_rmb() in reuseport_select_sock() */

	smp_wmb();

	reuse->num_socks++;

}



static bool __reuseport_detach_sock(struct sock *sk,

				    struct sock_reuseport *reuse)

{

	int i = reuseport_sock_index(sk, reuse, false);



	if (i == -1)

		return false;



	reuse->socks[i] = reuse->socks[reuse->num_socks - 1];

	reuse->num_socks--;



	return true;

}



static struct sock_reuseport *__reuseport_alloc(unsigned int max_socks)

{

	unsigned int size = sizeof(struct sock_reuseport) +
@@ -72,9 +115,9 @@ int reuseport_alloc(struct sock *sk, bool bind_inany) 
	}



	reuse->reuseport_id = id;

	reuse->bind_inany = bind_inany;

	reuse->socks[0] = sk;

	reuse->num_socks = 1;

	reuse->bind_inany = bind_inany;

	rcu_assign_pointer(sk->sk_reuseport_cb, reuse);



out:
@@ -98,6 +141,7 @@ static struct sock_reuseport *reuseport_grow(struct sock_reuseport *reuse) 
		return NULL;



	more_reuse->num_socks = reuse->num_socks;

	more_reuse->num_closed_socks = reuse->num_closed_socks;

	more_reuse->prog = reuse->prog;

	more_reuse->reuseport_id = reuse->reuseport_id;

	more_reuse->bind_inany = reuse->bind_inany;
@@ -105,9 +149,13 @@ static struct sock_reuseport *reuseport_grow(struct sock_reuseport *reuse) 


	memcpy(more_reuse->socks, reuse->socks,

	       reuse->num_socks * sizeof(struct sock *));

	memcpy(more_reuse->socks +

	       (more_reuse->max_socks - more_reuse->num_closed_socks),

	       reuse->socks + (reuse->max_socks - reuse->num_closed_socks),

	       reuse->num_closed_socks * sizeof(struct sock *));

	more_reuse->synq_overflow_ts = READ_ONCE(reuse->synq_overflow_ts);



	for (i = 0; i < reuse->num_socks; ++i)

	for (i = 0; i < reuse->max_socks; ++i)

		rcu_assign_pointer(reuse->socks[i]->sk_reuseport_cb,

				   more_reuse);
@@ -158,7 +206,7 @@ int reuseport_add_sock(struct sock *sk, struct sock *sk2, bool bind_inany) 
		return -EBUSY;

	}



	if (reuse->num_socks == reuse->max_socks) {

	if (reuse->num_socks + reuse->num_closed_socks == reuse->max_socks) {

		reuse = reuseport_grow(reuse);

		if (!reuse) {

			spin_unlock_bh(&reuseport_lock);
@@ -166,10 +214,7 @@ int reuseport_add_sock(struct sock *sk, struct sock *sk2, bool bind_inany) 
		}

	}



	reuse->socks[reuse->num_socks] = sk;

	/* paired with smp_rmb() in reuseport_select_sock() */

	smp_wmb();

	reuse->num_socks++;

	__reuseport_add_sock(sk, reuse);

	rcu_assign_pointer(sk->sk_reuseport_cb, reuse);



	spin_unlock_bh(&reuseport_lock);
@@ -183,7 +228,6 @@ EXPORT_SYMBOL(reuseport_add_sock); 
void reuseport_detach_sock(struct sock *sk)

{

	struct sock_reuseport *reuse;

	int i;



	spin_lock_bh(&reuseport_lock);

	reuse = rcu_dereference_protected(sk->sk_reuseport_cb,
@@ -200,16 +244,11 @@ void reuseport_detach_sock(struct sock *sk) 
	bpf_sk_reuseport_detach(sk);



	rcu_assign_pointer(sk->sk_reuseport_cb, NULL);

	__reuseport_detach_sock(sk, reuse);



	for (i = 0; i < reuse->num_socks; i++) {

		if (reuse->socks[i] == sk) {

			reuse->socks[i] = reuse->socks[reuse->num_socks - 1];

			reuse->num_socks--;

			if (reuse->num_socks == 0)

	if (reuse->num_socks + reuse->num_closed_socks == 0)

		call_rcu(&reuse->rcu, reuseport_free_rcu);

			break;

		}

	}



	spin_unlock_bh(&reuseport_lock);

}

EXPORT_SYMBOL(reuseport_detach_sock);
@@ -274,7 +313,7 @@ struct sock *reuseport_select_sock(struct sock *sk, 
	prog = rcu_dereference(reuse->prog);

	socks = READ_ONCE(reuse->num_socks);

	if (likely(socks)) {

		/* paired with smp_wmb() in reuseport_add_sock() */

		/* paired with smp_wmb() in __reuseport_add_sock() */

		smp_rmb();



		if (!prog || !skb)