Re: kern/42455: tstile hang with nfs

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

>  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