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From: DJBARROW@de.ibm.com
To: linux-kernel@vger.kernel.org
Subject: bug in /net/core/dev.c
Date: Mon, 11 Jun 2001 20:32:03 +0200	[thread overview]
Message-ID: <C1256A68.0065E17F.00@d12mta09.de.ibm.com> (raw)

[-- Attachment #1: Type: text/plain, Size: 776 bytes --]




Hi,
I found this bug in dev.c

It happens if register_netdevice is called before net_dev_init which can
happen from init functions,
when device drivers are compiled into the kernel.

The dev->refcnt will go up to 2 ( it should be 1) unregister_netdevice will
usually  loop forever
waiting for the refcnt to drop to 1 when an attempt to unregister is done.

The printk in the bootmessages early initialization of device <blah> is
deferred is evidence of this behaviour occuring.

The small patch is below ,hope it is okay for you.

(See attached file: dev.c.2.4.5.patch)

D.J. Barrow Gnu/Linux for S/390 kernel developer
eMail: djbarrow@de.ibm.com,barrow_dj@yahoo.com
Phone: +49-(0)7031-16-2583
IBM Germany Lab, Schönaicherstr. 220, 71032 Böblingen

[-- Attachment #2: dev.c.2.4.5.patch --]
[-- Type: application/octet-stream, Size: 900 bytes --]

--- net/core/dev.old.c	Mon Jun 11 20:00:42 2001
+++ net/core/dev.c	Mon Jun 11 19:51:55 2001
@@ -20,6 +20,9 @@
  *              Pekka Riikonen <priikone@poesidon.pspt.fi>
  *
  *	Changes:
+ *              D.J. Barrow     :       Fixed net_dev_init calling dev_hold & setting
+ *                                      The dev->refcnt to 2 if register_netdev gets 
+ *                                      called first & initialization is deferred.
  *		Alan Cox	:	device private ioctl copies fields back.
  *		Alan Cox	:	Transmit queue code does relevant stunts to
  *					keep the queue safe.
@@ -2733,8 +2736,10 @@
 #endif
 		dev->xmit_lock_owner = -1;
 		dev->iflink = -1;
-		dev_hold(dev);
-
+		/* Can't do dev_hold here in case
+		 *  register_netdev gets called first.
+		 */
+		atomic_set(&dev->refcnt,1);
 		/*
 		 * Allocate name. If the init() fails
 		 * the name will be reissued correctly.

             reply	other threads:[~2001-06-11 18:33 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2001-06-11 18:32 DJBARROW [this message]
2001-06-12  3:18 ` David S. Miller
2001-06-12 14:17 DJBARROW
2001-06-12 14:57 ` David S. Miller
2001-06-12 15:34   ` Keith Owens
2001-06-12 15:46   ` David S. Miller
2001-06-12 16:11     ` Keith Owens
2001-06-12 16:43 DJBARROW
2001-06-12 16:51 ` David S. Miller
2001-06-12 17:02 ` Keith Owens
2001-06-12 17:05 Ulrich.Weigand
2001-06-12 17:20 ` Keith Owens
2001-06-12 18:38 DJBARROW
2001-06-12 18:44 ` David S. Miller
2001-06-13 10:03 DJBARROW
2001-06-13 10:18 ` David S. Miller

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