Merging upstream version 4.19.269.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 24 insertions, 61 deletions

diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c
index ef2543a4c..c0034546a 100644
--- a/net/kcm/kcmsock.c
+++ b/net/kcm/kcmsock.c
@@ -164,7 +164,8 @@ static void kcm_rcv_ready(struct kcm_sock *kcm)
 	/* Buffer limit is okay now, add to ready list */
 	list_add_tail(&kcm->wait_rx_list,
 		      &kcm->mux->kcm_rx_waiters);
-	kcm->rx_wait = true;
+	/* paired with lockless reads in kcm_rfree() */
+	WRITE_ONCE(kcm->rx_wait, true);
 }
 
 static void kcm_rfree(struct sk_buff *skb)
@@ -180,7 +181,7 @@ static void kcm_rfree(struct sk_buff *skb)
 	/* For reading rx_wait and rx_psock without holding lock */
 	smp_mb__after_atomic();
 
-	if (!kcm->rx_wait && !kcm->rx_psock &&
+	if (!READ_ONCE(kcm->rx_wait) && !READ_ONCE(kcm->rx_psock) &&
 	    sk_rmem_alloc_get(sk) < sk->sk_rcvlowat) {
 		spin_lock_bh(&mux->rx_lock);
 		kcm_rcv_ready(kcm);
@@ -223,7 +224,7 @@ static void requeue_rx_msgs(struct kcm_mux *mux, struct sk_buff_head *head)
 	struct sk_buff *skb;
 	struct kcm_sock *kcm;
 
-	while ((skb = __skb_dequeue(head))) {
+	while ((skb = skb_dequeue(head))) {
 		/* Reset destructor to avoid calling kcm_rcv_ready */
 		skb->destructor = sock_rfree;
 		skb_orphan(skb);
@@ -239,7 +240,8 @@ try_again:
 		if (kcm_queue_rcv_skb(&kcm->sk, skb)) {
 			/* Should mean socket buffer full */
 			list_del(&kcm->wait_rx_list);
-			kcm->rx_wait = false;
+			/* paired with lockless reads in kcm_rfree() */
+			WRITE_ONCE(kcm->rx_wait, false);
 
 			/* Commit rx_wait to read in kcm_free */
 			smp_wmb();
@@ -282,10 +284,12 @@ static struct kcm_sock *reserve_rx_kcm(struct kcm_psock *psock,
 	kcm = list_first_entry(&mux->kcm_rx_waiters,
 			       struct kcm_sock, wait_rx_list);
 	list_del(&kcm->wait_rx_list);
-	kcm->rx_wait = false;
+	/* paired with lockless reads in kcm_rfree() */
+	WRITE_ONCE(kcm->rx_wait, false);
 
 	psock->rx_kcm = kcm;
-	kcm->rx_psock = psock;
+	/* paired with lockless reads in kcm_rfree() */
+	WRITE_ONCE(kcm->rx_psock, psock);
 
 	spin_unlock_bh(&mux->rx_lock);
 
@@ -312,7 +316,8 @@ static void unreserve_rx_kcm(struct kcm_psock *psock,
 	spin_lock_bh(&mux->rx_lock);
 
 	psock->rx_kcm = NULL;
-	kcm->rx_psock = NULL;
+	/* paired with lockless reads in kcm_rfree() */
+	WRITE_ONCE(kcm->rx_psock, NULL);
 
 	/* Commit kcm->rx_psock before sk_rmem_alloc_get to sync with
 	 * kcm_rfree
@@ -1080,53 +1085,18 @@ out_error:
 	return err;
 }
 
-static struct sk_buff *kcm_wait_data(struct sock *sk, int flags,
-				     long timeo, int *err)
-{
-	struct sk_buff *skb;
-
-	while (!(skb = skb_peek(&sk->sk_receive_queue))) {
-		if (sk->sk_err) {
-			*err = sock_error(sk);
-			return NULL;
-		}
-
-		if (sock_flag(sk, SOCK_DONE))
-			return NULL;
-
-		if ((flags & MSG_DONTWAIT) || !timeo) {
-			*err = -EAGAIN;
-			return NULL;
-		}
-
-		sk_wait_data(sk, &timeo, NULL);
-
-		/* Handle signals */
-		if (signal_pending(current)) {
-			*err = sock_intr_errno(timeo);
-			return NULL;
-		}
-	}
-
-	return skb;
-}
-
 static int kcm_recvmsg(struct socket *sock, struct msghdr *msg,
 		       size_t len, int flags)
 {
+	int noblock = flags & MSG_DONTWAIT;
 	struct sock *sk = sock->sk;
 	struct kcm_sock *kcm = kcm_sk(sk);
 	int err = 0;
-	long timeo;
 	struct strp_msg *stm;
 	int copied = 0;
 	struct sk_buff *skb;
 
-	timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
-
-	lock_sock(sk);
-
-	skb = kcm_wait_data(sk, flags, timeo, &err);
+	skb = skb_recv_datagram(sk, flags, noblock, &err);
 	if (!skb)
 		goto out;
 
@@ -1157,14 +1127,11 @@ msg_finished:
 			/* Finished with message */
 			msg->msg_flags |= MSG_EOR;
 			KCM_STATS_INCR(kcm->stats.rx_msgs);
-			skb_unlink(skb, &sk->sk_receive_queue);
-			kfree_skb(skb);
 		}
 	}
 
 out:
-	release_sock(sk);
-
+	skb_free_datagram(sk, skb);
 	return copied ? : err;
 }
 
@@ -1172,9 +1139,9 @@ static ssize_t kcm_splice_read(struct socket *sock, loff_t *ppos,
 			       struct pipe_inode_info *pipe, size_t len,
 			       unsigned int flags)
 {
+	int noblock = flags & MSG_DONTWAIT;
 	struct sock *sk = sock->sk;
 	struct kcm_sock *kcm = kcm_sk(sk);
-	long timeo;
 	struct strp_msg *stm;
 	int err = 0;
 	ssize_t copied;
@@ -1182,11 +1149,7 @@ static ssize_t kcm_splice_read(struct socket *sock, loff_t *ppos,
 
 	/* Only support splice for SOCKSEQPACKET */
 
-	timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
-
-	lock_sock(sk);
-
-	skb = kcm_wait_data(sk, flags, timeo, &err);
+	skb = skb_recv_datagram(sk, flags, noblock, &err);
 	if (!skb)
 		goto err_out;
 
@@ -1214,13 +1177,11 @@ static ssize_t kcm_splice_read(struct socket *sock, loff_t *ppos,
 	 * finish reading the message.
 	 */
 
-	release_sock(sk);
-
+	skb_free_datagram(sk, skb);
 	return copied;
 
 err_out:
-	release_sock(sk);
-
+	skb_free_datagram(sk, skb);
 	return err;
 }
 
@@ -1240,7 +1201,8 @@ static void kcm_recv_disable(struct kcm_sock *kcm)
 	if (!kcm->rx_psock) {
 		if (kcm->rx_wait) {
 			list_del(&kcm->wait_rx_list);
-			kcm->rx_wait = false;
+			/* paired with lockless reads in kcm_rfree() */
+			WRITE_ONCE(kcm->rx_wait, false);
 		}
 
 		requeue_rx_msgs(mux, &kcm->sk.sk_receive_queue);
@@ -1793,7 +1755,8 @@ static void kcm_done(struct kcm_sock *kcm)
 
 	if (kcm->rx_wait) {
 		list_del(&kcm->wait_rx_list);
-		kcm->rx_wait = false;
+		/* paired with lockless reads in kcm_rfree() */
+		WRITE_ONCE(kcm->rx_wait, false);
 	}
 	/* Move any pending receive messages to other kcm sockets */
 	requeue_rx_msgs(mux, &sk->sk_receive_queue);
@@ -1838,10 +1801,10 @@ static int kcm_release(struct socket *sock)
 	kcm = kcm_sk(sk);
 	mux = kcm->mux;
 
+	lock_sock(sk);
 	sock_orphan(sk);
 	kfree_skb(kcm->seq_skb);
 
-	lock_sock(sk);
 	/* Purge queue under lock to avoid race condition with tx_work trying
 	 * to act when queue is nonempty. If tx_work runs after this point
 	 * it will just return.