2007/1/22, Kostik Belousov <[EMAIL PROTECTED]>:
On Mon, Jan 22, 2007 at 11:53:50AM +0000, Bjoern A. Zeeb wrote:
> On Mon, 22 Jan 2007, Konstantin Belousov wrote:
>
> >kib 2007-01-22 11:25:22 UTC
> >
> > FreeBSD src repository
> >
> > Modified files:
> > sys/fs/deadfs dead_vnops.c
> > sys/kern vfs_lookup.c
> > Log:
> > Below is slightly edited description of the LOR by Tor Egge:
> >
> > --------------------------
> > [Deadlock] is caused by a lock order reversal in vfs_lookup(), where
> > [some] process is trying to lock a directory vnode, that is the parent
> > directory of covered vnode) while holding an exclusive vnode lock on
> > covering vnode.
> >....
> > To fix the LOR, ups@ noted that when crossing the mount point, ni_dvp
> > is actually not used by the callers of namei. Thus, placeholder deadfs
> > vnode vp_crossmp is introduced that is filled into ni_dvp.
>
> which of the LOR #s on "The LOR page" can be marked "patched" with
> this commit?
>
> http://sources.zabbadoz.net/freebsd/lor.html
None, your page lists only LORs that are detectable by WITNESS. This one is
between lockmgr lock and vfs_busy(), both of them are invisible to WITNESS.
FYI, I tried to add WITNESS support to lockmgr but kernel hangs on a
vfs lockmgr. This is a very strange bug and it suggests their
implementation is very fragile (from this the necessity to rewrite
them: //depot/user/attilio/attilio_lockmgr/... on perforce).
--
Peace can only be achieved by understanding - A. Einstein
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