PATCH: missing unlock in ipconfig - and question: appletalk delays

[Neil Brown]

Hi,
 I compiled a new (2.4.13) kernel for my notebook which included
 appletalk support (just in case...) and found that I started getting
 lots of processes hanging in 'D' state.

 They were trying to down(&rtnl_sem);

 I did an audit of rtnl_sem usage and found an obscure case where an
 unlock was missing:

--- ./net/ipv4/ipconfig.c	2001/11/01 01:51:16	1.1
+++ ./net/ipv4/ipconfig.c	2001/11/01 02:42:26
@@ -194,8 +194,10 @@
 				printk(KERN_ERR "IP-Config: Failed to open %s\n", dev->name);
 				continue;
 			}
-			if (!(d = kmalloc(sizeof(struct ic_device), GFP_KERNEL)))
+			if (!(d = kmalloc(sizeof(struct ic_device), GFP_KERNEL))) {
+				rtnl_shunlock();
 				return -1;
+			}
 			d->dev = dev;
 			*last = d;
 			last = &d->next;

 But that wasn't the problem.  The problem was that atalkd was doing
 atif_probe_device under some sock_ioctl/atalk_ioctl/atif_ioctl and it
 was taking a long time, and holding the rtnl_sem semaphore the whole
 time. 
 The code suggests what it could try for some multiple of 253
 seconds,  which is several minutes.  During this time such simple
 commands as "netstat -i" wont work.

 It's probably OK for it to take a long time probing the network, but
 it is really fair that it hold the semaphore for the whole time??

 Fortunately it does interruptible waits so I can just kill atalkd (or
 maybe even not run it).

NeilBrown