cvs commit: src/sys/kern kern_lockf.c

Jeff Roberson jroberson at
Wed Mar 19 02:08:16 PDT 2008

On Wed, 19 Mar 2008, Doug Rabson wrote:

> On 19 Mar 2008, at 07:13, Jeff Roberson wrote:
>> jeff        2008-03-19 07:13:24 UTC
>> FreeBSD src repository
>> Modified files:
>>   sys/kern             kern_lockf.c
>> Log:
>>  - Fix the last of the threading bugs that were introduced as far back as
>>    1.38 in 2001.  Break out of the FOREACH_THREAD_IN_PROC loop when we've
>>    discovered a new proc in the chain.
>>  - Increment i and check for maxlockdepth once per matching process not
>>    once per thread.  This didn't properly terminate the loop before.
>>  - Fix a bug which has existed potentially since rev 1.1. 
>> waitblock->lf_next
>>    can be NULL when a thread has been woken-up but not yet scheduled. 
>> Check
>>    for this condition rather than blindly dereferencing.
>> Found by:       libMicro
>> Revision  Changes    Path
>> 1.59      +12 -6     src/sys/kern/kern_lockf.c
> I have completely removed all this proc tomfoolery in my perforce branch and 
> have replaced it with a real deadlock detection system instead of this 
> horrible code. Apart from anything else, the existing code has serious 
> locking problems - if the deadlock loop spans two or more vnodes, it doesn't 
> lock any but the first one.
> I should have a patch ready for review (along with the new kernel NFS lock 
> manager) towards the end of this week and I hope to get the thing into 
> -current some time next week.

Thanks very much Doug.  I'm looking forward to it!


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