5.4-p1 crash

[Philippe PEGON]

Philippe PEGON wrote:
> Mitch Parks wrote:
> 
>> On Sun, 19 Jun 2005, Doug White wrote:
>>
>>> On Fri, 17 Jun 2005, Mitch Parks wrote:
>>>
>>>> Below are details regarding another crash on a Dell 2600 SMP (HTT 
>>>> and USB
>>>> disabled). It has been 9 days since the last crash. I didn't have 
>>>> the serial
>>>> console in place for this last crash, but it is now.
>>>
>>>
>>>
>>> As noted, the ttwakeup() panic is a known bug. The best thing we have 
>>> for
>>> a fix is this patch:
>>>
>>> http://people.freebsd.org/~mlaier/tty.t_pgrp.diff
>>>
>>> Please give it a try and report back if you have any more panics (or
>>> don't :-) ).
>>
>>
>>
>> Thanks! This patch appears to be for 5.3, but I manually applied the 
>> chunk of the patch that didn't apply cleanly and the countdown is on.
>>
>> I'll report back in 10 days unless something bad happens before then.
>>
>> Below is the patch chunk #10 that I actually applied rather than the 
>> one given. If I've done something bad here by removing the PGRP_LOCK 
>> please let me know.
> 
> 
> I'm not a kernel developper, but if you remove
> 
> PGRP_LOCK(tp->t_pgrp);
> 
> and the PGRP_UNLOCK(tp->t_pgrp) in the if condition (removed by the 
> orginal patch)
> 
> there is maybe another "PGRP_UNLOCK(tp->t_pgrp);" to remove if the if 
> condition doesn't match, line 2528 in the original 5.4-p1 tty.c ?

after having applied the patch (with your modification), there is no 
"sx_sunlock(&proctree_lock)" in the ttyinfo function if the three 
conditions failed. Maybe we have just to replace 
"PGRP_UNLOCK(tp->t_pgrp);" line 2528 by "sx_sunlock(&proctree_lock)" ?
I think that we need the helps of a kernel developper.

> 
>>
>> ....
>> Hunk #6 succeeded at 1154 (offset -51 lines).
>> Hunk #7 succeeded at 1215 (offset -6 lines).
>> Hunk #8 succeeded at 1203 (offset -51 lines).
>> Hunk #9 succeeded at 1946 (offset -5 lines).
>> Hunk #10 failed at 2562.
>> Hunk #11 succeeded at 2847 (offset -212 lines).
>> 1 out of 11 hunks failed--saving rejects to tty.c.rej
>>
>>
>> @@ -2495,19 +2511,21 @@
>>          * On return following a ttyprintf(), we set tp->t_rocount to 
>> 0 so
>>          * that pending input will be retyped on BS.
>>          */
>> +       sx_slock(&proctree_lock);
>>         if (tp->t_session == NULL) {
>> +               sx_sunlock(&proctree_lock);
>>                 ttyprintf(tp, "not a controlling terminal\n");
>>                 tp->t_rocount = 0;
>>                 return;
>>         }
>>         if (tp->t_pgrp == NULL) {
>> +               sx_sunlock(&proctree_lock);
>>                 ttyprintf(tp, "no foreground process group\n");
>>                 tp->t_rocount = 0;
>>                 return;
>>         }
>> -       PGRP_LOCK(tp->t_pgrp);
>> -       if ((p = LIST_FIRST(&tp->t_pgrp->pg_members)) == 0) {
>> -               PGRP_UNLOCK(tp->t_pgrp);
>> +       if ((p = LIST_FIRST(&tp->t_pgrp->pg_members)) == NULL) {
>> +               sx_sunlock(&proctree_lock);
>>                 ttyprintf(tp, "empty foreground process group\n");
>>                 tp->t_rocount = 0;
>>                 return;
>>
>> Or the complete patch:
>> http://kuoi.asui.uidaho.edu/~mitch/crash/tty_5.4.patch
>>
>> Mitch Parks
>> mitch at kuoi.asui.uidaho.edu
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> 
> 


-- 
Philippe PEGON