From: Mark Rutland <mark.rutland@arm.com>
To: dsterba@suse.cz, linux-kernel@vger.kernel.org,
Will Deacon <will.deacon@arm.com>,
Kees Cook <keescook@chromium.org>,
Boqun Feng <boqun.feng@gmail.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>
Subject: Re: [PATCH] refcount: always allow checked forms
Date: Wed, 11 Jul 2018 06:49:46 +0100 [thread overview]
Message-ID: <20180711054946.wdkfoou6kt2a2vml@salmiak> (raw)
In-Reply-To: <20180704084641.GL3126@suse.cz>
On Wed, Jul 04, 2018 at 10:46:41AM +0200, David Sterba wrote:
> On Tue, Jul 03, 2018 at 11:01:02AM +0100, Mark Rutland wrote:
> > In many cases, it would be useful to be able to use the full
> > sanity-checked refcount helpers regardless of CONFIG_REFCOUNT_FULL, as
> > this would help to avoid duplicate warnings where callers try to
> > sanity-check refcount manipulation.
> >
> > This patch refactors things such that the full refcount helpers were
> > always built, as refcount_${op}_checked(), such that they can be used
> > regardless of CONFIG_REFCOUNT_FULL. This will allow code which *always*
> > wants a checked refcount to opt-in, avoiding the need to duplicate the
> > logic for warnings.
> >
> > There should be no functional change as a result of this patch.
> >
> > Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> > Cc: Boqun Feng <boqun.feng@gmail.com>
> > Cc: David Sterba <dsterba@suse.com>
> > Cc: Ingo Molnar <mingo@kernel.org>
> > Cc: Kees Cook <keescook@chromium.org>
> > Cc: Peter Zijlstra <peterz@infradead.org>
> > Cc: Peter Zijlstra <peterz@infradead.org>
> > Cc: Will Deacon <will.deacon@arm.com>
>
> I dare to give it my
>
> Reviewed-by: David Sterba <dsterba@suse.com>
Cheers!
> as my POC implementations were crap and Mark's version is much better.
Please don't think that your implementations were bad; I just already had an
idea as to what this could look like.
> > ---
> > include/linux/refcount.h | 27 +++++++++++++++++-------
> > lib/refcount.c | 53 +++++++++++++++++++++++-------------------------
> > 2 files changed, 45 insertions(+), 35 deletions(-)
> >
> > Dave pointed out that it would be useful to be able to opt-in to full checks
> > regardless of CONFIG_REFCOUNT_FULL, so that we can simplify callsites where we
> > always want checks. I've spotted a few of these in code which is still awaiting
> > conversion.
>
> The motivation was code like
>
> WARN_ON(refcount_read(&ref));
> if (refcount_dec_and_test(&ref)) { ... }
>
> so the warning is redundant for REFCOUNT_FULL, but I'm going to use the
> _checked versions everywhere the performance of refcounts is not
> critical.
If you will have conversion patches, do you want to pick this up as the start
of a series?
Thanks,
Mark.
next prev parent reply other threads:[~2018-07-11 5:49 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-03 10:01 [PATCH] refcount: always allow checked forms Mark Rutland
2018-07-03 10:33 ` Andrea Parri
2018-07-03 11:39 ` Mark Rutland
2018-07-03 18:30 ` Kees Cook
2018-07-11 5:44 ` Mark Rutland
2018-07-04 8:46 ` David Sterba
2018-07-11 5:49 ` Mark Rutland [this message]
2018-07-11 17:37 ` David Sterba
2018-07-12 12:08 ` Mark Rutland
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180711054946.wdkfoou6kt2a2vml@salmiak \
--to=mark.rutland@arm.com \
--cc=boqun.feng@gmail.com \
--cc=dsterba@suse.cz \
--cc=keescook@chromium.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=peterz@infradead.org \
--cc=will.deacon@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).