From: Kees Cook <keescook@chromium.org>
To: David Howells <dhowells@redhat.com>
Cc: peterz@infradead.org, Xiaoming Ni <nixiaoming@huawei.com>,
David Windsor <dwindsor@gmail.com>,
Hans Liljestrand <ishkamiel@gmail.com>,
Elena Reshetova <elena.reshetova@intel.com>,
Paul Moore <paul@paul-moore.com>,
edumazet@google.com, paulmck@kernel.org, shakeelb@google.com,
James Morris <jamorris@linux.microsoft.com>,
alex.huangjianhui@huawei.com, dylix.dailei@huawei.com,
chenzefeng2@huawei.com, linux-kernel@vger.kernel.org,
Will Deacon <will@kernel.org>
Subject: Re: [RFC][PATCH] locking/refcount: Provide __refcount API to obtain the old value
Date: Wed, 29 Jul 2020 13:52:56 -0700 [thread overview]
Message-ID: <202007291352.8775B08DA@keescook> (raw)
In-Reply-To: <4041520.1596055297@warthog.procyon.org.uk>
On Wed, Jul 29, 2020 at 09:41:37PM +0100, David Howells wrote:
> peterz@infradead.org wrote:
>
> > I'm not entirely sure what you mean with interpret, provided you don't
> > trigger a refcount fail, the number will be just what you expect and
> > would get from refcount_read(). If you do trigger a fail, you'll get a
> > negative value.
>
> That's fine. I seem to remember talk about the possibility that the number
> wouldn't necessarily bottom out at zero - for instance if it was arranged such
> that the overflow flag was set on an overflow or underflow so that it could be
> trapped on (using INTO or TRAPV, for example).
The trap is an internal detail. The saturation value will be negative,
though.
--
Kees Cook
next prev parent reply other threads:[~2020-07-29 20:53 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-12 18:34 [PATCH 0/3] Convert nsproxy, groups, and creds to refcount_t Kees Cook
2020-06-12 18:34 ` [PATCH 1/3] nsproxy: convert nsproxy.count " Kees Cook
2020-06-12 18:34 ` [PATCH 2/3] groups: convert group_info.usage " Kees Cook
2020-06-15 0:57 ` [groups] 67467ae141: will-it-scale.per_process_ops 4.3% improvement kernel test robot
2020-06-12 18:34 ` [PATCH 3/3] creds: convert cred.usage to refcount_t Kees Cook
2020-06-15 2:02 ` Xiaoming Ni
2020-06-15 2:10 ` [PATCH 0/3] Convert nsproxy, groups, and creds " Xiaoming Ni
2020-06-15 3:55 ` Kees Cook
2020-06-15 5:35 ` Reshetova, Elena
2020-06-15 18:08 ` Kees Cook
2020-06-18 7:39 ` Reshetova, Elena
2020-07-21 11:02 ` David Howells
2020-07-21 10:51 ` David Howells
2020-07-21 18:44 ` Kees Cook
2020-07-21 19:51 ` Peter Zijlstra
2020-07-28 10:56 ` David Howells
2020-07-29 11:11 ` [RFC][PATCH] locking/refcount: Provide __refcount API to obtain the old value peterz
2020-07-29 11:37 ` peterz
2020-07-29 19:29 ` Kees Cook
2020-07-29 19:30 ` Kees Cook
2020-07-29 20:41 ` David Howells
2020-07-29 20:52 ` Kees Cook [this message]
2020-08-27 7:54 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2020-09-21 11:22 ` [RFC][PATCH] " Will Deacon
2021-01-26 11:25 ` David Howells
2020-07-28 11:01 ` [PATCH 0/3] Convert nsproxy, groups, and creds to refcount_t David Howells
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=202007291352.8775B08DA@keescook \
--to=keescook@chromium.org \
--cc=alex.huangjianhui@huawei.com \
--cc=chenzefeng2@huawei.com \
--cc=dhowells@redhat.com \
--cc=dwindsor@gmail.com \
--cc=dylix.dailei@huawei.com \
--cc=edumazet@google.com \
--cc=elena.reshetova@intel.com \
--cc=ishkamiel@gmail.com \
--cc=jamorris@linux.microsoft.com \
--cc=linux-kernel@vger.kernel.org \
--cc=nixiaoming@huawei.com \
--cc=paul@paul-moore.com \
--cc=paulmck@kernel.org \
--cc=peterz@infradead.org \
--cc=shakeelb@google.com \
--cc=will@kernel.org \
/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