Re: kern/50186: sparc memfault panic after 7.99.21 ARP changes

[Ryota Ozaki <ozaki-r%netbsd.org@localhost>]

The following reply was made to PR kern/50186; it has been noted by GNATS.

From: Ryota Ozaki <ozaki-r%netbsd.org@localhost>
To: Christos Zoulas <christos%zoulas.com@localhost>
Cc: "gnats-bugs%NetBSD.org@localhost" <gnats-bugs%netbsd.org@localhost>, 
	"kern-bug-people%netbsd.org@localhost" <kern-bug-people%netbsd.org@localhost>, 
	"gnats-admin%netbsd.org@localhost" <gnats-admin%netbsd.org@localhost>, "netbsd-bugs%netbsd.org@localhost" <netbsd-bugs%netbsd.org@localhost>, 
	"jdbaker%mylinuxisp.com@localhost" <jdbaker%mylinuxisp.com@localhost>
Subject: Re: kern/50186: sparc memfault panic after 7.99.21 ARP changes
Date: Fri, 4 Sep 2015 13:50:52 +0900

 On Thu, Sep 3, 2015 at 8:38 PM, Christos Zoulas <christos%zoulas.com@localhost> wrote:
 > I just crashed in arptimer() so there are more locking problems in the code. Can you document the locking discipline for la_rt and changing the lists?
 >
 
 I'm sorry for the defect.
 
 An ARP cache list of an interface is protected by a rwlock
 (IF_AFDATA_*LOCK) and each ARP cache is protected by a rwlock
 and refernce counting (LLE_*LOCK). However, la_rt still needs
 softnet_lock; if la_rt is accessed or modified without
 softnet_lock, it's a bug. And I found a bug :( lltable_free
 accesses la_rt but it's called without softnet_lock.
 
 Here is a patch:
 http://www.netbsd.org/~ozaki-r/lltable_free-softnet_lock.diff
 Could you try it?
 
 Thanks,
   ozaki-r