v4.19.13 snapshot.
diff --git a/drivers/connector/connector.c b/drivers/connector/connector.c
new file mode 100644
index 0000000..eeb7d31
--- /dev/null
+++ b/drivers/connector/connector.c
@@ -0,0 +1,306 @@
+/*
+ * connector.c
+ *
+ * 2004+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
+ * All rights reserved.
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include <linux/compiler.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/list.h>
+#include <linux/skbuff.h>
+#include <net/netlink.h>
+#include <linux/moduleparam.h>
+#include <linux/connector.h>
+#include <linux/slab.h>
+#include <linux/mutex.h>
+#include <linux/proc_fs.h>
+#include <linux/spinlock.h>
+
+#include <net/sock.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");
+MODULE_DESCRIPTION("Generic userspace <-> kernelspace connector.");
+MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_CONNECTOR);
+
+static struct cn_dev cdev;
+
+static int cn_already_initialized;
+
+/*
+ * Sends mult (multiple) cn_msg at a time.
+ *
+ * msg->seq and msg->ack are used to determine message genealogy.
+ * When someone sends message it puts there locally unique sequence
+ * and random acknowledge numbers. Sequence number may be copied into
+ * nlmsghdr->nlmsg_seq too.
+ *
+ * Sequence number is incremented with each message to be sent.
+ *
+ * If we expect a reply to our message then the sequence number in
+ * received message MUST be the same as in original message, and
+ * acknowledge number MUST be the same + 1.
+ *
+ * If we receive a message and its sequence number is not equal to the
+ * one we are expecting then it is a new message.
+ *
+ * If we receive a message and its sequence number is the same as one
+ * we are expecting but it's acknowledgement number is not equal to
+ * the acknowledgement number in the original message + 1, then it is
+ * a new message.
+ *
+ * If msg->len != len, then additional cn_msg messages are expected following
+ * the first msg.
+ *
+ * The message is sent to, the portid if given, the group if given, both if
+ * both, or if both are zero then the group is looked up and sent there.
+ */
+int cn_netlink_send_mult(struct cn_msg *msg, u16 len, u32 portid, u32 __group,
+ gfp_t gfp_mask)
+{
+ struct cn_callback_entry *__cbq;
+ unsigned int size;
+ struct sk_buff *skb;
+ struct nlmsghdr *nlh;
+ struct cn_msg *data;
+ struct cn_dev *dev = &cdev;
+ u32 group = 0;
+ int found = 0;
+
+ if (portid || __group) {
+ group = __group;
+ } else {
+ spin_lock_bh(&dev->cbdev->queue_lock);
+ list_for_each_entry(__cbq, &dev->cbdev->queue_list,
+ callback_entry) {
+ if (cn_cb_equal(&__cbq->id.id, &msg->id)) {
+ found = 1;
+ group = __cbq->group;
+ break;
+ }
+ }
+ spin_unlock_bh(&dev->cbdev->queue_lock);
+
+ if (!found)
+ return -ENODEV;
+ }
+
+ if (!portid && !netlink_has_listeners(dev->nls, group))
+ return -ESRCH;
+
+ size = sizeof(*msg) + len;
+
+ skb = nlmsg_new(size, gfp_mask);
+ if (!skb)
+ return -ENOMEM;
+
+ nlh = nlmsg_put(skb, 0, msg->seq, NLMSG_DONE, size, 0);
+ if (!nlh) {
+ kfree_skb(skb);
+ return -EMSGSIZE;
+ }
+
+ data = nlmsg_data(nlh);
+
+ memcpy(data, msg, size);
+
+ NETLINK_CB(skb).dst_group = group;
+
+ if (group)
+ return netlink_broadcast(dev->nls, skb, portid, group,
+ gfp_mask);
+ return netlink_unicast(dev->nls, skb, portid,
+ !gfpflags_allow_blocking(gfp_mask));
+}
+EXPORT_SYMBOL_GPL(cn_netlink_send_mult);
+
+/* same as cn_netlink_send_mult except msg->len is used for len */
+int cn_netlink_send(struct cn_msg *msg, u32 portid, u32 __group,
+ gfp_t gfp_mask)
+{
+ return cn_netlink_send_mult(msg, msg->len, portid, __group, gfp_mask);
+}
+EXPORT_SYMBOL_GPL(cn_netlink_send);
+
+/*
+ * Callback helper - queues work and setup destructor for given data.
+ */
+static int cn_call_callback(struct sk_buff *skb)
+{
+ struct nlmsghdr *nlh;
+ struct cn_callback_entry *i, *cbq = NULL;
+ struct cn_dev *dev = &cdev;
+ struct cn_msg *msg = nlmsg_data(nlmsg_hdr(skb));
+ struct netlink_skb_parms *nsp = &NETLINK_CB(skb);
+ int err = -ENODEV;
+
+ /* verify msg->len is within skb */
+ nlh = nlmsg_hdr(skb);
+ if (nlh->nlmsg_len < NLMSG_HDRLEN + sizeof(struct cn_msg) + msg->len)
+ return -EINVAL;
+
+ spin_lock_bh(&dev->cbdev->queue_lock);
+ list_for_each_entry(i, &dev->cbdev->queue_list, callback_entry) {
+ if (cn_cb_equal(&i->id.id, &msg->id)) {
+ refcount_inc(&i->refcnt);
+ cbq = i;
+ break;
+ }
+ }
+ spin_unlock_bh(&dev->cbdev->queue_lock);
+
+ if (cbq != NULL) {
+ cbq->callback(msg, nsp);
+ kfree_skb(skb);
+ cn_queue_release_callback(cbq);
+ err = 0;
+ }
+
+ return err;
+}
+
+/*
+ * Main netlink receiving function.
+ *
+ * It checks skb, netlink header and msg sizes, and calls callback helper.
+ */
+static void cn_rx_skb(struct sk_buff *skb)
+{
+ struct nlmsghdr *nlh;
+ int len, err;
+
+ if (skb->len >= NLMSG_HDRLEN) {
+ nlh = nlmsg_hdr(skb);
+ len = nlmsg_len(nlh);
+
+ if (len < (int)sizeof(struct cn_msg) ||
+ skb->len < nlh->nlmsg_len ||
+ len > CONNECTOR_MAX_MSG_SIZE)
+ return;
+
+ err = cn_call_callback(skb_get(skb));
+ if (err < 0)
+ kfree_skb(skb);
+ }
+}
+
+/*
+ * Callback add routing - adds callback with given ID and name.
+ * If there is registered callback with the same ID it will not be added.
+ *
+ * May sleep.
+ */
+int cn_add_callback(struct cb_id *id, const char *name,
+ void (*callback)(struct cn_msg *,
+ struct netlink_skb_parms *))
+{
+ int err;
+ struct cn_dev *dev = &cdev;
+
+ if (!cn_already_initialized)
+ return -EAGAIN;
+
+ err = cn_queue_add_callback(dev->cbdev, name, id, callback);
+ if (err)
+ return err;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(cn_add_callback);
+
+/*
+ * Callback remove routing - removes callback
+ * with given ID.
+ * If there is no registered callback with given
+ * ID nothing happens.
+ *
+ * May sleep while waiting for reference counter to become zero.
+ */
+void cn_del_callback(struct cb_id *id)
+{
+ struct cn_dev *dev = &cdev;
+
+ cn_queue_del_callback(dev->cbdev, id);
+}
+EXPORT_SYMBOL_GPL(cn_del_callback);
+
+static int __maybe_unused cn_proc_show(struct seq_file *m, void *v)
+{
+ struct cn_queue_dev *dev = cdev.cbdev;
+ struct cn_callback_entry *cbq;
+
+ seq_printf(m, "Name ID\n");
+
+ spin_lock_bh(&dev->queue_lock);
+
+ list_for_each_entry(cbq, &dev->queue_list, callback_entry) {
+ seq_printf(m, "%-15s %u:%u\n",
+ cbq->id.name,
+ cbq->id.id.idx,
+ cbq->id.id.val);
+ }
+
+ spin_unlock_bh(&dev->queue_lock);
+
+ return 0;
+}
+
+static struct cn_dev cdev = {
+ .input = cn_rx_skb,
+};
+
+static int cn_init(void)
+{
+ struct cn_dev *dev = &cdev;
+ struct netlink_kernel_cfg cfg = {
+ .groups = CN_NETLINK_USERS + 0xf,
+ .input = dev->input,
+ };
+
+ dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR, &cfg);
+ if (!dev->nls)
+ return -EIO;
+
+ dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls);
+ if (!dev->cbdev) {
+ netlink_kernel_release(dev->nls);
+ return -EINVAL;
+ }
+
+ cn_already_initialized = 1;
+
+ proc_create_single("connector", S_IRUGO, init_net.proc_net, cn_proc_show);
+
+ return 0;
+}
+
+static void cn_fini(void)
+{
+ struct cn_dev *dev = &cdev;
+
+ cn_already_initialized = 0;
+
+ remove_proc_entry("connector", init_net.proc_net);
+
+ cn_queue_free_dev(dev->cbdev);
+ netlink_kernel_release(dev->nls);
+}
+
+subsys_initcall(cn_init);
+module_exit(cn_fini);