Re: kern/42455: tstile hang with nfs

[Christoph Egger <Christoph_Egger%gmx.de@localhost>]

The following reply was made to PR kern/42455; it has been noted by GNATS.

From: Christoph Egger <Christoph_Egger%gmx.de@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost, 
 netbsd-bugs%netbsd.org@localhost
Subject: Re: kern/42455: tstile hang with nfs
Date: Thu, 21 Oct 2010 19:38:33 +0200

 >  next=0x0 => mb is not a chained mbuf.
 >  
 >  nwc.mbuf_count is initialized with 1
 >  and nwc.mbuf_count is decreased by one right before it enters
 >  the while loop with 'cv_wait' so ctxt.nwc_mbuf_count must have
 >  been 2 before it entered the loop.
 >  
 >  There is only one way to increase nwc.mbuf_count: it must run
 >  the path where MEXTADD() is used which chains an mbuf to 'mb'.
 
 I added some more debug lines and figured out that the macro
 nfsm_wcc_data() drops the mbuf chain w/o decreasing ctxt.nwc_mbufcount.
 
 Christoph