[PATCH 16/36] net: add support for ->poll_mask in proto_ops

Christoph Hellwig
2018-01-17T19:37:06Z

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

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
include/linux/net.h | 3 +++
net/socket.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++-----
2 files changed, 49 insertions(+), 5 deletions(-)

diff --git a/include/linux/net.h b/include/linux/net.h
index c2d468cb9821..2d58d583d29a 100644
--- a/include/linux/net.h
+++ b/include/linux/net.h
@@ -147,6 +147,9 @@ struct proto_ops {
int (*getname) (struct socket *sock,
struct sockaddr *addr,
int *sockaddr_len, int peer);
+ struct wait_queue_head *(*get_poll_head)(struct socket *sock,
+ __poll_t events);
+ __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 db11e48a375b..21d50c5d4af4 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -118,8 +118,10 @@ 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,
@@ -142,6 +144,8 @@ 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
@@ -1094,14 +1098,51 @@ int sock_create_lite(int family, int type, int protocol, struct socket **res)
}
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;
+ if (sock->ops->get_poll_head)
+ return sock->ops->get_poll_head(sock, events);
+
+ 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)
--
2.14.2