Date: Fri, 18 Apr 1997 09:00:02 -0700 (PDT) From: Thomas David Rivers <ponds!rivers@dg-rtp.dg.com> To: freebsd-bugs Subject: Re: kern/3304: NFS V2 readdir hangs Message-ID: <199704181600.JAA13507@freefall.freebsd.org>
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The following reply was made to PR kern/3304; it has been noted by GNATS.
From: Thomas David Rivers <ponds!rivers@dg-rtp.dg.com>
To: ponds!lakes.water.net!rivers, ponds!khavrinen.lcs.mit.edu!wollman
Cc: ponds!freefall.freebsd.org!freebsd-gnats-submit
Subject: Re: kern/3304: NFS V2 readdir hangs
Date: Fri, 18 Apr 1997 11:49:35 -0400 (EDT)
More information...
Here's the scenario I've now determined (via more printf()s in the
kernel):
1) nfs_request() is called from readdirrpc().
2) nfs_request malloc's a nfsreq block, which is used
by rcvlock()... the lock is granted; we go down to
soreceive() and wind up tsleeping in sbwait().
3) At this point, a vnode lookup() operation is called.
The lookup() isn't satisfied from the cache; so
we call nfs_request() to get the information.
4) This nfs_request() malloc's a different nfsreq block.
The "lock" is granted since rcvlock() works on addresses
from the nfsreq block; these are different addresses, the
lock is granted. We wind down to soreceive()
again.
5) udp_intr() is called because a UDP packet arrived...
this is, presumably, the packet we're expecting from 2).
*however* the last request we received was from 4).
That is the nfsreq this packet winds up being associated
with; but - it is totally wrong.
So; we're left with the lookup() failing with a ENONENT (#2),
and the nfs_request from #2 hanging; never being woken up.
I think that pretty well describes my findings.
Perhaps the rcvlock() needs to change to lock on something other
than the nfsreq block... does anyone have any suggestions?
- Dave Rivers -
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