From owner-freebsd-current  Sat Sep 29 20:27:45 2001
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Date: Sat, 29 Sep 2001 20:24:47 -0700 (PDT)
From: John Baldwin <jhb@FreeBSD.org>
To: Marcel Moolenaar <marcel@xcllnt.net>
Subject: Re: panic: blockable sleep lock (sx) ...
Cc: current@FreeBSD.org
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On 30-Sep-01 Marcel Moolenaar wrote:
> On Sat, Sep 29, 2001 at 12:52:48PM -0700, John Baldwin wrote:
>> 
>> could figure out the faulting address that it trapp'd one that would help. 
>> You
>> could add KTR tracepoints or some such to store the log message to do that
>> and
>> then examin the KTR buffer to get the actual faulting address.
> 
> Ok. In the remote debugger I got a lot more data. In fact, it
> brought me to linux_alarm() in /sys/compat/linux_misc.c
> 
> First some data about the trapping thread:
> 
> td = curthread = 0xcbb89304           looks ok
> kg = td->ksegrp = 0xcbb89230          looks ok
> 
> td->td_proc->p_comm = "swi6: tty:sio clock"
> 
> The LTP test that seems to be causing this is doing an alarm().
> 
> In linux_alarm() I see:
> 
>       :
>       s = splsoftclock();
>       old_it = td->td_proc->p_realtimer;
>       :
>       td->td_proc->p_realtimer = it;
>       splx(s);
>       :
> 
> Is the splsoftclock() acceptable locking to access td->td_proc?

For now the code should be fine b/c it is under Giant.  (The spl's don't dp
anything anymore.)

-- 

John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/
PGP Key: http://www.baldwin.cx/~john/pgpkey.asc
"Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/

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