linux-kernel - Re: [PATCH 2/2] module: fix building stats for 32-bit targets

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Message-ID: <ZD3WEDSlsg+ki3Ie@bombadil.infradead.org>
Date:   Mon, 17 Apr 2023 16:28:16 -0700
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Arnd Bergmann <arnd@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Aaron Tomlin <atomlin@...hat.com>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Viktor Malik <vmalik@...hat.com>,
        Jason Baron <jbaron@...mai.com>, Song Liu <song@...nel.org>,
        Jim Cromie <jim.cromie@...il.com>,
        Kees Cook <keescook@...omium.org>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Sami Tolvanen <samitolvanen@...gle.com>,
        linux-modules@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] module: fix building stats for 32-bit targets

On Tue, Apr 18, 2023 at 12:49:29AM +0200, Arnd Bergmann wrote:
> On Tue, Apr 18, 2023, at 00:15, Luis Chamberlain wrote:
> > On Tue, Apr 18, 2023 at 12:02:47AM +0200, Arnd Bergmann wrote:
> >> I have no idea if there is a risk of these variables actually
> >> overflowing 'long' on 32-bit machines. If they provably can't, it
> >> would be better to do the opposite patch.
> >
> > I had originally used atomic64_t and added a debugfs knob for it but
> > Linus had advised against it because its not a stat we care too much
> > on 32-bit and atomic64 is nasty on 32-bit [0].
> >
> > So I went with atomic_long and the cast becuase we're just reading.
> > 
> > Is there a way to fix this without doing the fully jump? If not oh well.
> 
> I've sent a v2 now that does it the other way round, which is
> clearly much more efficient. Have only done minimal build testing
> so far, but it passes the randconfigs that failed before.

Thanks! You're too fast.

  Luis