add new system file

hc

2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c

 kernel/drivers/media/dvb-core/dvb_net.c
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@@ -1,3 +1,4 @@
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+// SPDX-License-Identifier: GPL-2.0-or-later
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 /*
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  * dvb_net.c
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  *
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@@ -13,18 +14,6 @@
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  *                      and Wolfram Stering <wstering@cosy.sbg.ac.at>
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  *
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  * ULE Decaps according to RFC 4326.
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- *
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- * This program is free software; you can redistribute it and/or
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- * modify it under the terms of the GNU General Public License
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- * as published by the Free Software Foundation; either version 2
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- * of the License, or (at your option) any later version.
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- *
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- * This program is distributed in the hope that it will be useful,
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- * but WITHOUT ANY WARRANTY; without even the implied warranty of
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- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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- * GNU General Public License for more details.
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- * To obtain the license, point your browser to
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- * http://www.gnu.org/copyleft/gpl.html
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  */
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 /*
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@@ -558,7 +547,7 @@
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 		h->priv->ule_sndu_type_1 = 1;
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 		h->ts_remain -= 1;
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 		h->from_where += 1;
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-		/* fallthrough */
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+		fallthrough;
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 	case 0:
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 		h->new_ts = 1;
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 		h->ts += TS_SZ;
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@@ -1575,15 +1564,43 @@
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 	return dvb_usercopy(file, cmd, arg, dvb_net_do_ioctl);
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 }
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+static int locked_dvb_net_open(struct inode *inode, struct file *file)
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+{
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+	struct dvb_device *dvbdev = file->private_data;
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+	struct dvb_net *dvbnet = dvbdev->priv;
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+	int ret;
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+
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+	if (mutex_lock_interruptible(&dvbnet->remove_mutex))
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+		return -ERESTARTSYS;
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+
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+	if (dvbnet->exit) {
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+		mutex_unlock(&dvbnet->remove_mutex);
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+		return -ENODEV;
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+	}
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+
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+	ret = dvb_generic_open(inode, file);
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+
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+	mutex_unlock(&dvbnet->remove_mutex);
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+
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+	return ret;
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+}
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+
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 static int dvb_net_close(struct inode *inode, struct file *file)
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 {
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 	struct dvb_device *dvbdev = file->private_data;
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 	struct dvb_net *dvbnet = dvbdev->priv;
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+	mutex_lock(&dvbnet->remove_mutex);
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+
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 	dvb_generic_release(inode, file);
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-	if(dvbdev->users == 1 && dvbnet->exit == 1)
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+	if (dvbdev->users == 1 && dvbnet->exit == 1) {
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+		mutex_unlock(&dvbnet->remove_mutex);
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 		wake_up(&dvbdev->wait_queue);
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+	} else {
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+		mutex_unlock(&dvbnet->remove_mutex);
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+	}
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+
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 	return 0;
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 }
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@@ -1591,7 +1608,7 @@
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 static const struct file_operations dvb_net_fops = {
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 	.owner = THIS_MODULE,
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 	.unlocked_ioctl = dvb_net_ioctl,
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-	.open =	dvb_generic_open,
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+	.open =	locked_dvb_net_open,
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 	.release = dvb_net_close,
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 	.llseek = noop_llseek,
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 };
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@@ -1610,10 +1627,13 @@
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 {
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 	int i;
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+	mutex_lock(&dvbnet->remove_mutex);
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 	dvbnet->exit = 1;
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+	mutex_unlock(&dvbnet->remove_mutex);
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+
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 	if (dvbnet->dvbdev->users < 1)
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 		wait_event(dvbnet->dvbdev->wait_queue,
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-				dvbnet->dvbdev->users==1);
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+				dvbnet->dvbdev->users == 1);
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 	dvb_unregister_device(dvbnet->dvbdev);
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@@ -1632,6 +1652,7 @@
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 	int i;
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 	mutex_init(&dvbnet->ioctl_mutex);
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+	mutex_init(&dvbnet->remove_mutex);
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 	dvbnet->demux = dmx;
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 	for (i=0; i<DVB_NET_DEVICES_MAX; i++)