linux/net/nfc/rawsock.c
Linus Torvalds a11e1d432b Revert changes to convert to ->poll_mask() and aio IOCB_CMD_POLL
The poll() changes were not well thought out, and completely
unexplained.  They also caused a huge performance regression, because
"->poll()" was no longer a trivial file operation that just called down
to the underlying file operations, but instead did at least two indirect
calls.

Indirect calls are sadly slow now with the Spectre mitigation, but the
performance problem could at least be largely mitigated by changing the
"->get_poll_head()" operation to just have a per-file-descriptor pointer
to the poll head instead.  That gets rid of one of the new indirections.

But that doesn't fix the new complexity that is completely unwarranted
for the regular case.  The (undocumented) reason for the poll() changes
was some alleged AIO poll race fixing, but we don't make the common case
slower and more complex for some uncommon special case, so this all
really needs way more explanations and most likely a fundamental
redesign.

[ This revert is a revert of about 30 different commits, not reverted
  individually because that would just be unnecessarily messy  - Linus ]

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-06-28 10:40:47 -07:00

433 lines
9.6 KiB
C

/*
* Copyright (C) 2011 Instituto Nokia de Tecnologia
*
* Authors:
* Aloisio Almeida Jr <aloisio.almeida@openbossa.org>
* Lauro Ramos Venancio <lauro.venancio@openbossa.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": %s: " fmt, __func__
#include <net/tcp_states.h>
#include <linux/nfc.h>
#include <linux/export.h>
#include "nfc.h"
static struct nfc_sock_list raw_sk_list = {
.lock = __RW_LOCK_UNLOCKED(raw_sk_list.lock)
};
static void nfc_sock_link(struct nfc_sock_list *l, struct sock *sk)
{
write_lock(&l->lock);
sk_add_node(sk, &l->head);
write_unlock(&l->lock);
}
static void nfc_sock_unlink(struct nfc_sock_list *l, struct sock *sk)
{
write_lock(&l->lock);
sk_del_node_init(sk);
write_unlock(&l->lock);
}
static void rawsock_write_queue_purge(struct sock *sk)
{
pr_debug("sk=%p\n", sk);
spin_lock_bh(&sk->sk_write_queue.lock);
__skb_queue_purge(&sk->sk_write_queue);
nfc_rawsock(sk)->tx_work_scheduled = false;
spin_unlock_bh(&sk->sk_write_queue.lock);
}
static void rawsock_report_error(struct sock *sk, int err)
{
pr_debug("sk=%p err=%d\n", sk, err);
sk->sk_shutdown = SHUTDOWN_MASK;
sk->sk_err = -err;
sk->sk_error_report(sk);
rawsock_write_queue_purge(sk);
}
static int rawsock_release(struct socket *sock)
{
struct sock *sk = sock->sk;
pr_debug("sock=%p sk=%p\n", sock, sk);
if (!sk)
return 0;
if (sock->type == SOCK_RAW)
nfc_sock_unlink(&raw_sk_list, sk);
sock_orphan(sk);
sock_put(sk);
return 0;
}
static int rawsock_connect(struct socket *sock, struct sockaddr *_addr,
int len, int flags)
{
struct sock *sk = sock->sk;
struct sockaddr_nfc *addr = (struct sockaddr_nfc *)_addr;
struct nfc_dev *dev;
int rc = 0;
pr_debug("sock=%p sk=%p flags=%d\n", sock, sk, flags);
if (!addr || len < sizeof(struct sockaddr_nfc) ||
addr->sa_family != AF_NFC)
return -EINVAL;
pr_debug("addr dev_idx=%u target_idx=%u protocol=%u\n",
addr->dev_idx, addr->target_idx, addr->nfc_protocol);
lock_sock(sk);
if (sock->state == SS_CONNECTED) {
rc = -EISCONN;
goto error;
}
dev = nfc_get_device(addr->dev_idx);
if (!dev) {
rc = -ENODEV;
goto error;
}
if (addr->target_idx > dev->target_next_idx - 1 ||
addr->target_idx < dev->target_next_idx - dev->n_targets) {
rc = -EINVAL;
goto error;
}
rc = nfc_activate_target(dev, addr->target_idx, addr->nfc_protocol);
if (rc)
goto put_dev;
nfc_rawsock(sk)->dev = dev;
nfc_rawsock(sk)->target_idx = addr->target_idx;
sock->state = SS_CONNECTED;
sk->sk_state = TCP_ESTABLISHED;
sk->sk_state_change(sk);
release_sock(sk);
return 0;
put_dev:
nfc_put_device(dev);
error:
release_sock(sk);
return rc;
}
static int rawsock_add_header(struct sk_buff *skb)
{
*(u8 *)skb_push(skb, NFC_HEADER_SIZE) = 0;
return 0;
}
static void rawsock_data_exchange_complete(void *context, struct sk_buff *skb,
int err)
{
struct sock *sk = (struct sock *) context;
BUG_ON(in_irq());
pr_debug("sk=%p err=%d\n", sk, err);
if (err)
goto error;
err = rawsock_add_header(skb);
if (err)
goto error_skb;
err = sock_queue_rcv_skb(sk, skb);
if (err)
goto error_skb;
spin_lock_bh(&sk->sk_write_queue.lock);
if (!skb_queue_empty(&sk->sk_write_queue))
schedule_work(&nfc_rawsock(sk)->tx_work);
else
nfc_rawsock(sk)->tx_work_scheduled = false;
spin_unlock_bh(&sk->sk_write_queue.lock);
sock_put(sk);
return;
error_skb:
kfree_skb(skb);
error:
rawsock_report_error(sk, err);
sock_put(sk);
}
static void rawsock_tx_work(struct work_struct *work)
{
struct sock *sk = to_rawsock_sk(work);
struct nfc_dev *dev = nfc_rawsock(sk)->dev;
u32 target_idx = nfc_rawsock(sk)->target_idx;
struct sk_buff *skb;
int rc;
pr_debug("sk=%p target_idx=%u\n", sk, target_idx);
if (sk->sk_shutdown & SEND_SHUTDOWN) {
rawsock_write_queue_purge(sk);
return;
}
skb = skb_dequeue(&sk->sk_write_queue);
sock_hold(sk);
rc = nfc_data_exchange(dev, target_idx, skb,
rawsock_data_exchange_complete, sk);
if (rc) {
rawsock_report_error(sk, rc);
sock_put(sk);
}
}
static int rawsock_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
{
struct sock *sk = sock->sk;
struct nfc_dev *dev = nfc_rawsock(sk)->dev;
struct sk_buff *skb;
int rc;
pr_debug("sock=%p sk=%p len=%zu\n", sock, sk, len);
if (msg->msg_namelen)
return -EOPNOTSUPP;
if (sock->state != SS_CONNECTED)
return -ENOTCONN;
skb = nfc_alloc_send_skb(dev, sk, msg->msg_flags, len, &rc);
if (skb == NULL)
return rc;
rc = memcpy_from_msg(skb_put(skb, len), msg, len);
if (rc < 0) {
kfree_skb(skb);
return rc;
}
spin_lock_bh(&sk->sk_write_queue.lock);
__skb_queue_tail(&sk->sk_write_queue, skb);
if (!nfc_rawsock(sk)->tx_work_scheduled) {
schedule_work(&nfc_rawsock(sk)->tx_work);
nfc_rawsock(sk)->tx_work_scheduled = true;
}
spin_unlock_bh(&sk->sk_write_queue.lock);
return len;
}
static int rawsock_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
int flags)
{
int noblock = flags & MSG_DONTWAIT;
struct sock *sk = sock->sk;
struct sk_buff *skb;
int copied;
int rc;
pr_debug("sock=%p sk=%p len=%zu flags=%d\n", sock, sk, len, flags);
skb = skb_recv_datagram(sk, flags, noblock, &rc);
if (!skb)
return rc;
copied = skb->len;
if (len < copied) {
msg->msg_flags |= MSG_TRUNC;
copied = len;
}
rc = skb_copy_datagram_msg(skb, 0, msg, copied);
skb_free_datagram(sk, skb);
return rc ? : copied;
}
static const struct proto_ops rawsock_ops = {
.family = PF_NFC,
.owner = THIS_MODULE,
.release = rawsock_release,
.bind = sock_no_bind,
.connect = rawsock_connect,
.socketpair = sock_no_socketpair,
.accept = sock_no_accept,
.getname = sock_no_getname,
.poll = datagram_poll,
.ioctl = sock_no_ioctl,
.listen = sock_no_listen,
.shutdown = sock_no_shutdown,
.setsockopt = sock_no_setsockopt,
.getsockopt = sock_no_getsockopt,
.sendmsg = rawsock_sendmsg,
.recvmsg = rawsock_recvmsg,
.mmap = sock_no_mmap,
};
static const struct proto_ops rawsock_raw_ops = {
.family = PF_NFC,
.owner = THIS_MODULE,
.release = rawsock_release,
.bind = sock_no_bind,
.connect = sock_no_connect,
.socketpair = sock_no_socketpair,
.accept = sock_no_accept,
.getname = sock_no_getname,
.poll = datagram_poll,
.ioctl = sock_no_ioctl,
.listen = sock_no_listen,
.shutdown = sock_no_shutdown,
.setsockopt = sock_no_setsockopt,
.getsockopt = sock_no_getsockopt,
.sendmsg = sock_no_sendmsg,
.recvmsg = rawsock_recvmsg,
.mmap = sock_no_mmap,
};
static void rawsock_destruct(struct sock *sk)
{
pr_debug("sk=%p\n", sk);
if (sk->sk_state == TCP_ESTABLISHED) {
nfc_deactivate_target(nfc_rawsock(sk)->dev,
nfc_rawsock(sk)->target_idx,
NFC_TARGET_MODE_IDLE);
nfc_put_device(nfc_rawsock(sk)->dev);
}
skb_queue_purge(&sk->sk_receive_queue);
if (!sock_flag(sk, SOCK_DEAD)) {
pr_err("Freeing alive NFC raw socket %p\n", sk);
return;
}
}
static int rawsock_create(struct net *net, struct socket *sock,
const struct nfc_protocol *nfc_proto, int kern)
{
struct sock *sk;
pr_debug("sock=%p\n", sock);
if ((sock->type != SOCK_SEQPACKET) && (sock->type != SOCK_RAW))
return -ESOCKTNOSUPPORT;
if (sock->type == SOCK_RAW)
sock->ops = &rawsock_raw_ops;
else
sock->ops = &rawsock_ops;
sk = sk_alloc(net, PF_NFC, GFP_ATOMIC, nfc_proto->proto, kern);
if (!sk)
return -ENOMEM;
sock_init_data(sock, sk);
sk->sk_protocol = nfc_proto->id;
sk->sk_destruct = rawsock_destruct;
sock->state = SS_UNCONNECTED;
if (sock->type == SOCK_RAW)
nfc_sock_link(&raw_sk_list, sk);
else {
INIT_WORK(&nfc_rawsock(sk)->tx_work, rawsock_tx_work);
nfc_rawsock(sk)->tx_work_scheduled = false;
}
return 0;
}
void nfc_send_to_raw_sock(struct nfc_dev *dev, struct sk_buff *skb,
u8 payload_type, u8 direction)
{
struct sk_buff *skb_copy = NULL, *nskb;
struct sock *sk;
u8 *data;
read_lock(&raw_sk_list.lock);
sk_for_each(sk, &raw_sk_list.head) {
if (!skb_copy) {
skb_copy = __pskb_copy_fclone(skb, NFC_RAW_HEADER_SIZE,
GFP_ATOMIC, true);
if (!skb_copy)
continue;
data = skb_push(skb_copy, NFC_RAW_HEADER_SIZE);
data[0] = dev ? dev->idx : 0xFF;
data[1] = direction & 0x01;
data[1] |= (payload_type << 1);
}
nskb = skb_clone(skb_copy, GFP_ATOMIC);
if (!nskb)
continue;
if (sock_queue_rcv_skb(sk, nskb))
kfree_skb(nskb);
}
read_unlock(&raw_sk_list.lock);
kfree_skb(skb_copy);
}
EXPORT_SYMBOL(nfc_send_to_raw_sock);
static struct proto rawsock_proto = {
.name = "NFC_RAW",
.owner = THIS_MODULE,
.obj_size = sizeof(struct nfc_rawsock),
};
static const struct nfc_protocol rawsock_nfc_proto = {
.id = NFC_SOCKPROTO_RAW,
.proto = &rawsock_proto,
.owner = THIS_MODULE,
.create = rawsock_create
};
int __init rawsock_init(void)
{
int rc;
rc = nfc_proto_register(&rawsock_nfc_proto);
return rc;
}
void rawsock_exit(void)
{
nfc_proto_unregister(&rawsock_nfc_proto);
}