add new system file

hc

2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c

 kernel/net/ax25/ax25_dev.c
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@@ -1,8 +1,5 @@
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+// SPDX-License-Identifier: GPL-2.0-or-later
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 /*
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- * This program is free software; you can redistribute it and/or modify
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- * it under the terms of the GNU General Public License as published by
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- * the Free Software Foundation; either version 2 of the License, or
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- * (at your option) any later version.
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  *
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  * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
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  */
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@@ -40,6 +37,7 @@
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 	for (ax25_dev = ax25_dev_list; ax25_dev != NULL; ax25_dev = ax25_dev->next)
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 		if (ax25cmp(addr, (ax25_address *)ax25_dev->dev->dev_addr) == 0) {
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 			res = ax25_dev;
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+			ax25_dev_hold(ax25_dev);
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 		}
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 	spin_unlock_bh(&ax25_dev_lock);
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@@ -59,6 +57,7 @@
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 		return;
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 	}
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+	refcount_set(&ax25_dev->refcount, 1);
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 	dev->ax25_ptr     = ax25_dev;
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 	ax25_dev->dev     = dev;
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 	dev_hold(dev);
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@@ -87,6 +86,7 @@
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 	ax25_dev->next = ax25_dev_list;
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 	ax25_dev_list  = ax25_dev;
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 	spin_unlock_bh(&ax25_dev_lock);
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+	ax25_dev_hold(ax25_dev);
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 	ax25_register_dev_sysctl(ax25_dev);
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 }
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@@ -116,9 +116,10 @@
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 	if ((s = ax25_dev_list) == ax25_dev) {
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 		ax25_dev_list = s->next;
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 		spin_unlock_bh(&ax25_dev_lock);
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+		ax25_dev_put(ax25_dev);
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 		dev->ax25_ptr = NULL;
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 		dev_put(dev);
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-		kfree(ax25_dev);
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+		ax25_dev_put(ax25_dev);
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 		return;
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 	}
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@@ -126,9 +127,10 @@
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 		if (s->next == ax25_dev) {
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 			s->next = ax25_dev->next;
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 			spin_unlock_bh(&ax25_dev_lock);
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+			ax25_dev_put(ax25_dev);
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 			dev->ax25_ptr = NULL;
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 			dev_put(dev);
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-			kfree(ax25_dev);
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+			ax25_dev_put(ax25_dev);
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 			return;
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 		}
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@@ -136,6 +138,7 @@
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 	}
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 	spin_unlock_bh(&ax25_dev_lock);
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 	dev->ax25_ptr = NULL;
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+	ax25_dev_put(ax25_dev);
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 }
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 int ax25_fwd_ioctl(unsigned int cmd, struct ax25_fwd_struct *fwd)
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@@ -147,20 +150,32 @@
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 	switch (cmd) {
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 	case SIOCAX25ADDFWD:
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-		if ((fwd_dev = ax25_addr_ax25dev(&fwd->port_to)) == NULL)
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+		fwd_dev = ax25_addr_ax25dev(&fwd->port_to);
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+		if (!fwd_dev) {
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+			ax25_dev_put(ax25_dev);
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 			return -EINVAL;
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-		if (ax25_dev->forward != NULL)
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+		}
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+		if (ax25_dev->forward) {
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+			ax25_dev_put(fwd_dev);
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+			ax25_dev_put(ax25_dev);
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 			return -EINVAL;
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+		}
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 		ax25_dev->forward = fwd_dev->dev;
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+		ax25_dev_put(fwd_dev);
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+		ax25_dev_put(ax25_dev);
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 		break;
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 	case SIOCAX25DELFWD:
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-		if (ax25_dev->forward == NULL)
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+		if (!ax25_dev->forward) {
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+			ax25_dev_put(ax25_dev);
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 			return -EINVAL;
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+		}
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 		ax25_dev->forward = NULL;
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+		ax25_dev_put(ax25_dev);
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 		break;
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 	default:
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+		ax25_dev_put(ax25_dev);
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 		return -EINVAL;
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 	}
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