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SubjectRe: [RFC PATCH v1 07/25] printk-rb: add functionality required by printk
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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

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