Re: [PATCH] ring-buffer: use READ_ONCE() to read cpu_buffer->commit_page in concurrent environment

linke
2024-03-01T05:42:39Z

> So basically you are worried about read-tearing?
>
> That wasn't mentioned in the change log.

Yes. Sorry for making this confused, I am not very familiar with this and
still learning.

> Funny part is, if the above timestamp read did a tear, then this would
> definitely not match, and would return the correct value. That is, the
> buffer is not empty because the only way for this to get corrupted is if
> something is in the process of writing to it.

I agree with you here.

commit = rb_page_commit(commit_page);

But if commit_page above is the result of a torn read, the commit field
read by rb_page_commit() may not represent a valid value.

In this case, READ_ONCE() is only needed for the commit_page.