1 files changed, 40 insertions, 15 deletions

diff --git a/net/socket.c b/net/socket.c
index f10f1d947c78..2d752e9eb3f9 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -117,8 +117,10 @@ static ssize_t sock_write_iter(struct kiocb *iocb, struct iov_iter *from);
 static int sock_mmap(struct file *file, struct vm_area_struct *vma);
 
 static int sock_close(struct inode *inode, struct file *file);
-static __poll_t sock_poll(struct file *file,
-			      struct poll_table_struct *wait);
+static struct wait_queue_head *sock_get_poll_head(struct file *file,
+		__poll_t events);
+static __poll_t sock_poll_mask(struct file *file, __poll_t);
+static __poll_t sock_poll(struct file *file, struct poll_table_struct *wait);
 static long sock_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
 #ifdef CONFIG_COMPAT
 static long compat_sock_ioctl(struct file *file,
@@ -141,6 +143,8 @@ static const struct file_operations socket_file_ops = {
 	.llseek =	no_llseek,
 	.read_iter =	sock_read_iter,
 	.write_iter =	sock_write_iter,
+	.get_poll_head = sock_get_poll_head,
+	.poll_mask =	sock_poll_mask,
 	.poll =		sock_poll,
 	.unlocked_ioctl = sock_ioctl,
 #ifdef CONFIG_COMPAT
@@ -1114,27 +1118,48 @@ out_release:
 }
 EXPORT_SYMBOL(sock_create_lite);
 
-/* No kernel lock held - perfect */
-static __poll_t sock_poll(struct file *file, poll_table *wait)
+static struct wait_queue_head *sock_get_poll_head(struct file *file,
+		__poll_t events)
 {
-	__poll_t busy_flag = 0;
-	struct socket *sock;
+	struct socket *sock = file->private_data;
+
+	if (!sock->ops->poll_mask)
+		return NULL;
+	sock_poll_busy_loop(sock, events);
+	return sk_sleep(sock->sk);
+}
+
+static __poll_t sock_poll_mask(struct file *file, __poll_t events)
+{
+	struct socket *sock = file->private_data;
 
 	/*
-	 *      We can't return errors to poll, so it's either yes or no.
+	 * We need to be sure we are in sync with the socket flags modification.
+	 *
+	 * This memory barrier is paired in the wq_has_sleeper.
 	 */
-	sock = file->private_data;
+	smp_mb();
+
+	/* this socket can poll_ll so tell the system call */
+	return sock->ops->poll_mask(sock, events) |
+		(sk_can_busy_loop(sock->sk) ? POLL_BUSY_LOOP : 0);
+}
 
-	if (sk_can_busy_loop(sock->sk)) {
-		/* this socket can poll_ll so tell the system call */
-		busy_flag = POLL_BUSY_LOOP;
+/* No kernel lock held - perfect */
+static __poll_t sock_poll(struct file *file, poll_table *wait)
+{
+	struct socket *sock = file->private_data;
+	__poll_t events = poll_requested_events(wait), mask = 0;
 
-		/* once, only if requested by syscall */
-		if (wait && (wait->_key & POLL_BUSY_LOOP))
-			sk_busy_loop(sock->sk, 1);
+	if (sock->ops->poll) {
+		sock_poll_busy_loop(sock, events);
+		mask = sock->ops->poll(file, sock, wait);
+	} else if (sock->ops->poll_mask) {
+		sock_poll_wait(file, sock_get_poll_head(file, events), wait);
+		mask = sock->ops->poll_mask(sock, events);
 	}
 
-	return busy_flag | sock->ops->poll(file, sock, wait);
+	return mask | sock_poll_busy_flag(sock);
 }
 
 static int sock_mmap(struct file *file, struct vm_area_struct *vma)