net: add support for ->poll_mask in proto_ops

The socket file operations still implement ->poll until all protocols are
switched over.

Signed-off-by: Christoph Hellwig <hch@lst.de>

diff --git a/include/linux/net.h b/include/linux/net.h
index 2248a05..3fd9d8c 100644 (file)
--- a/include/linux/net.h
+++ b/include/linux/net.h
@@ -147,6 +147,7 @@ struct proto_ops {
        int             (*getname)   (struct socket *sock,
                                      struct sockaddr *addr,
                                      int peer);
+       __poll_t        (*poll_mask) (struct socket *sock, __poll_t events);
        __poll_t        (*poll)      (struct file *file, struct socket *sock,
                                      struct poll_table_struct *wait);
        int             (*ioctl)     (struct socket *sock, unsigned int cmd,

diff --git a/net/socket.c b/net/socket.c
index 571ee40..2d752e9 100644 (file)
--- 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
@@ -1114,14 +1118,48 @@ out_release:
 }
 EXPORT_SYMBOL(sock_create_lite);
 
+static struct wait_queue_head *sock_get_poll_head(struct file *file,
+               __poll_t events)
+{
+       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 need to be sure we are in sync with the socket flags modification.
+        *
+        * This memory barrier is paired in the wq_has_sleeper.
+        */
+       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);
+}
+
 /* 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);
+       __poll_t events = poll_requested_events(wait), mask = 0;
 
-       sock_poll_busy_loop(sock, events);
-       return sock->ops->poll(file, sock, wait) | sock_poll_busy_flag(sock);
+       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 mask | sock_poll_busy_flag(sock);
 }
 
 static int sock_mmap(struct file *file, struct vm_area_struct *vma)