lkml.org 
[lkml]   [2019]   [Nov]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: KCSAN: data-race in __alloc_file / __alloc_file
On Fri, Nov 8, 2019 at 9:39 AM Linus Torvalds
<torvalds@linux-foundation.org> wrote:

> I'd hope that there is some way to mark the cases we know about where
> we just have a flag. I'm not sure what KCSAN uses right now - is it
> just the "volatile" that makes KCSAN ignore it, or are there other
> ways to do it?

I dunno, Marco will comment on this.

I personally like WRITE_ONCE() since it adds zero overhead on generated code,
and is the facto accessor we used for many years (before KCSAN was conceived)

>
> "volatile" has huge problems with code generation for gcc. It would
> probably be fine for "not_rcu" in this case, but I'd like to avoid it
> in general otherwise, which is why I wonder if there are other
> options.
>
> But worst comes to worst, I'd be ok with a WRITE_ONCE() and a comment
> about why (and the reason being KCSAN, not the questionable
> optimization).

Ok for a single WRITE_ONCE() with a comment.

Hmm, which questionable optimization are you referring to?

\
 
 \ /
  Last update: 2019-11-08 18:54    [W:0.057 / U:24.360 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site