lkml.org 
[lkml]   [2019]   [Feb]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [RFC PATCH v1 07/25] printk-rb: add functionality required by printk
Date
On 2019-02-12, Linus Torvalds <torvalds@linux-foundation.org> wrote:
> On Tue, Feb 12, 2019 at 6:30 AM John Ogness <john.ogness@linutronix.de> wrote:
>>
>> + while (atomic_long_read(&rb->lost)) {
>> + atomic_long_dec(&rb->lost);
>> + rb->seq++;
>> + }
>
> This looks like crazy garbage. It's neither atomic nor sane.

It works because because only 1 context on a single CPU can hit that
loop. But yes, it is crazy.

> Why isn't it something like
>
> if (atomic_long_read(&rb->lost)) {
> long lost = atomic_xchg(&rb->lost, 0);
> rb->seq += lost;
> }
>
> instead?

Yes, it should be like you suggest. Thanks.

John Ogness

\
 
 \ /
  Last update: 2019-02-13 10:21    [W:0.373 / U:1.480 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site