lkml.org 
[lkml]   [2004]   [Mar]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: more efficient current_is_keventd macro? [was Re: [lhcs-devel] Re: Kthread_create() never returns when called from worker_thread]
Srivatsa Vaddagiri <vatsa@in.ibm.com> wrote:
>
> current_is_keventd() macro checks "current" with the per-cpu
> thread of _all_ possible cpus attached to keventd_wq. Can't it just check
> against the per-cpu thread of _current_ cpu alone (since the per-cpu workqueue
> threads are anyway bound only to their cpus)?

Seems that way, yes.

> int current_is_keventd(void)
> {
> struct cpu_workqueue_struct *cwq;
> - int cpu;
> + int cpu = smp_processor_id();
>
> BUG_ON(!keventd_wq);
>
> - for_each_cpu(cpu) {
> - cwq = keventd_wq->cpu_wq + cpu;
> - if (current == cwq->thread)
> - return 1;
> - }
>
> - return 0;
>
> + cwq = keventd_wq->cpu_wq + cpu;
> + if (current == cwq->thread)
> + return 1;
> + else
> + return 0;
> }

Is racy in the presence of preemption. Please replace smp_processor_id()
with get_cpu(), stick a put_cpu() at the end, avoid having two function
return points, test it and send me the diff?

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 14:01    [W:0.041 / U:0.700 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site