[RFC PATCH 62/62] coallocate socket->wq with socket itself

Al Viro
2019-04-16T17:54:45Z

socket->wq is assign-once, set when we are initializing both
struct socket it's in and struct socket_wq it points to. As the
matter of fact, the only reason for separate allocation was the
ability to RCU-delay freeing of socket_wq. RCU-delaying the
freeing of socket itself gets rid of that need, so we can just
fold struct socket_wq into the end of struct socket and simplify
the life both for sock_alloc_inode() (one allocation instead of
two) and for tun/tap oddballs, where we used to embed struct socket
and struct socket_wq into the same structure (now - embedding just
the struct socket).

Note that reference to struct socket_wq in struct sock does remain
a reference - that's unchanged.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
drivers/net/tap.c | 5 ++---
drivers/net/tun.c | 8 +++-----
include/linux/if_tap.h | 1 -
include/linux/net.h | 4 ++--
include/net/sock.h | 4 ++--
net/core/sock.c | 2 +-
net/socket.c | 19 +++++--------------
7 files changed, 15 insertions(+), 28 deletions(-)

diff --git a/drivers/net/tap.c b/drivers/net/tap.c
index 2ea9b4976f4a..249bfd85b65c 100644
--- a/drivers/net/tap.c
+++ b/drivers/net/tap.c
@@ -519,8 +519,7 @@ static int tap_open(struct inode *inode, struct file *file)
goto err;
}

- RCU_INIT_POINTER(q->sock.wq, &q->wq);
- init_waitqueue_head(&q->wq.wait);
+ init_waitqueue_head(&q->sock.wq.wait);
q->sock.type = SOCK_RAW;
q->sock.state = SS_CONNECTED;
q->sock.file = file;
@@ -578,7 +577,7 @@ static __poll_t tap_poll(struct file *file, poll_table *wait)
goto out;

mask = 0;
- poll_wait(file, &q->wq.wait, wait);
+ poll_wait(file, &q->sock.wq.wait, wait);

if (!ptr_ring_empty(&q->ring))
mask |= EPOLLIN | EPOLLRDNORM;
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index e9ca1c088d0b..f404d1588e9c 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -169,7 +169,6 @@ struct tun_pcpu_stats {
struct tun_file {
struct sock sk;
struct socket socket;
- struct socket_wq wq;
struct tun_struct __rcu *tun;
struct fasync_struct *fasync;
/* only used for fasnyc */
@@ -2174,7 +2173,7 @@ static void *tun_ring_recv(struct tun_file *tfile, int noblock, int *err)
goto out;
}

- add_wait_queue(&tfile->wq.wait, &wait);
+ add_wait_queue(&tfile->socket.wq.wait, &wait);

while (1) {
set_current_state(TASK_INTERRUPTIBLE);
@@ -2194,7 +2193,7 @@ static void *tun_ring_recv(struct tun_file *tfile, int noblock, int *err)
}

__set_current_state(TASK_RUNNING);
- remove_wait_queue(&tfile->wq.wait, &wait);
+ remove_wait_queue(&tfile->socket.wq.wait, &wait);

out:
*err = error;
@@ -3417,8 +3416,7 @@ static int tun_chr_open(struct inode *inode, struct file * file)
tfile->flags = 0;
tfile->ifindex = 0;

- init_waitqueue_head(&tfile->wq.wait);
- RCU_INIT_POINTER(tfile->socket.wq, &tfile->wq);
+ init_waitqueue_head(&tfile->socket.wq.wait);

tfile->socket.file = file;
tfile->socket.ops = &tun_socket_ops;
diff --git a/include/linux/if_tap.h b/include/linux/if_tap.h
index 8e66866c11be..915a187cfabd 100644
--- a/include/linux/if_tap.h
+++ b/include/linux/if_tap.h
@@ -62,7 +62,6 @@ struct tap_dev {
struct tap_queue {
struct sock sk;
struct socket sock;
- struct socket_wq wq;
int vnet_hdr_sz;
struct tap_dev __rcu *tap;
struct file *file;
diff --git a/include/linux/net.h b/include/linux/net.h
index c606c72311d0..6979057c7c86 100644
--- a/include/linux/net.h
+++ b/include/linux/net.h
@@ -120,11 +120,11 @@ struct socket {

unsigned long flags;

- struct socket_wq *wq;
-
struct file *file;
struct sock *sk;
const struct proto_ops *ops;
+
+ struct socket_wq wq;
};

struct vm_area_struct;
diff --git a/include/net/sock.h b/include/net/sock.h
index 8de5ee258b93..0e1975b6202f 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1811,7 +1811,7 @@ static inline void sock_graft(struct sock *sk, struct socket *parent)
{
WARN_ON(parent->sk);
write_lock_bh(&sk->sk_callback_lock);
- rcu_assign_pointer(sk->sk_wq, parent->wq);
+ rcu_assign_pointer(sk->sk_wq, &parent->wq);
parent->sk = sk;
sk_set_socket(sk, parent);
sk->sk_uid = SOCK_INODE(parent)->i_uid;
@@ -2095,7 +2095,7 @@ static inline void sock_poll_wait(struct file *filp, struct socket *sock,
poll_table *p)
{
if (!poll_does_not_wait(p)) {
- poll_wait(filp, &sock->wq->wait, p);
+ poll_wait(filp, &sock->wq.wait, p);
/* We need to be sure we are in sync with the
* socket flags modification.
*
diff --git a/net/core/sock.c b/net/core/sock.c
index 782343bb925b..11af1ee7d542 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2842,7 +2842,7 @@ void sock_init_data(struct socket *sock, struct sock *sk)

if (sock) {
sk->sk_type = sock->type;
- RCU_INIT_POINTER(sk->sk_wq, sock->wq);
+ RCU_INIT_POINTER(sk->sk_wq, &sock->wq);
sock->sk = sk;
sk->sk_uid = SOCK_INODE(sock)->i_uid;
} else {
diff --git a/net/socket.c b/net/socket.c
index 6953a049fb82..7d3d043fc56f 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -239,20 +239,13 @@ static struct kmem_cache *sock_inode_cachep __ro_after_init;
static struct inode *sock_alloc_inode(struct super_block *sb)
{
struct socket_alloc *ei;
- struct socket_wq *wq;

ei = kmem_cache_alloc(sock_inode_cachep, GFP_KERNEL);
if (!ei)
return NULL;
- wq = kmalloc(sizeof(*wq), GFP_KERNEL);
- if (!wq) {
- kmem_cache_free(sock_inode_cachep, ei);
- return NULL;
- }
- init_waitqueue_head(&wq->wait);
- wq->fasync_list = NULL;
- wq->flags = 0;
- ei->socket.wq = wq;
+ init_waitqueue_head(&ei->socket.wq.wait);
+ ei->socket.wq.fasync_list = NULL;
+ ei->socket.wq.flags = 0;

ei->socket.state = SS_UNCONNECTED;
ei->socket.flags = 0;
@@ -268,7 +261,6 @@ static void sock_free_inode(struct inode *inode)
struct socket_alloc *ei;

ei = container_of(inode, struct socket_alloc, vfs_inode);
- kfree(ei->socket.wq);
kmem_cache_free(sock_inode_cachep, ei);
}

@@ -604,7 +596,7 @@ static void __sock_release(struct socket *sock, struct inode *inode)
module_put(owner);
}

- if (sock->wq->fasync_list)
+ if (sock->wq.fasync_list)
pr_err("%s: fasync list not empty!\n", __func__);

if (!sock->file) {
@@ -1263,13 +1255,12 @@ static int sock_fasync(int fd, struct file *filp, int on)
{
struct socket *sock = filp->private_data;
struct sock *sk = sock->sk;
- struct socket_wq *wq;
+ struct socket_wq *wq = &sock->wq;

if (sk == NULL)
return -EINVAL;

lock_sock(sk);
- wq = sock->wq;
fasync_helper(fd, filp, on, &wq->fasync_list);

if (!wq->fasync_list)
--
2.11.0