Kernel Thread Lock Question

Julian Elischer julian at elischer.org
Mon Oct 5 17:55:26 UTC 2009


Tom Judge wrote:
> Do I need to hold the per thread lock here? (This is for 7.1)
> 
> PROC_LOCK(p);
> //mtx_lock_spin(&sched_lock);
> breakout = 0;
> FOREACH_THREAD_IN_PROC(p, td) {
>    thread_lock(td);
>    if (!TD_ON_RUNQ(td) &&
>            !TD_IS_RUNNING(td) &&
>            !TD_IS_SLEEPING(td)) {
>        breakout = 1;
>        thread_unlock(td);
>        break;
>    }
>    thread_unlock(td);
> }
> //mtx_unlock_spin(&sched_lock);
> PROC_UNLOCK(p);
> 

"probably not" because the value in the status word can change just 
after you release it anyhow so your result does not have to be 
consistent with anything, just with itself.

> 
> Thanks
> 
> Tom
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