lkml.org 
[lkml]   [2014]   [Feb]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 01/51] CPU hotplug: Provide lockless versions of callback registration functions
On 02/12, Srivatsa S. Bhat wrote:
>
> On 02/11/2014 10:45 PM, Oleg Nesterov wrote:
> >
> > I am a bit confused... If we do this, why we can't simply turn
> > cpu_add_remove_lock into rw_semaphore?

[...snip...]

> cpu_notifier_register_begin(); | Run in parallel
> | with similar phases
> for_each_online_cpu(cpu) | from other subsystems.
> init_cpu(cpu); |
>
> /* Updates the cpu notifier chain. */
> register_cpu_notifier(&foobar_cpu_notifier); ||| -- Must run serially

Ah indeed, we can't use a single lock, thanks. Perhaps we can simply
add a spinlock_t which only protects cpu_chain though, but I am not
sure and currently this is off-topic anyway.

Thanks,

Oleg.



\
 
 \ /
  Last update: 2014-02-13 20:21    [W:0.226 / U:0.020 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site