From: Peter Zijlstra <peterz@infradead.org>
To: Kees Cook <keescook@chromium.org>
Cc: David Howells <dhowells@redhat.com>,
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
Subject: Re: [PATCH 0/3] Convert nsproxy, groups, and creds to refcount_t
Date: Tue, 21 Jul 2020 21:51:32 +0200 [thread overview]
Message-ID: <20200721195132.GJ10769@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <202007211144.A68C31D@keescook>
On Tue, Jul 21, 2020 at 11:44:53AM -0700, Kees Cook wrote:
> On Tue, Jul 21, 2020 at 11:51:04AM +0100, David Howells wrote:
> > Kees Cook <keescook@chromium.org> wrote:
> >
> > > > Should mm->mm_users also be replaced by refcount_t?
> > >
> > > I'll say "yes". :)
> > > https://lore.kernel.org/lkml/1487671124-11188-1-git-send-email-elena.reshetova@intel.com/
> > >
> > > > In addition, is it better to change all variables that use
> > > > atomic_dec_and_test to control the release process to refconut_t?
> > >
> > > For the most part, yes. The following may find a lot of them:
> > > scripts/coccinelle/api/atomic_as_refcounter.cocci
> >
> > I've been gradually undoing some of the conversions as there's no equivalent
> > of atomic_add_return() and atomic_dec_return() that allow me to log the
> > altered refcount through a tracepoint.
>
> Please do not _undo_ the changes; just add the API you need.
add_return and sub_return are horrible interface for refcount, which is
the problem.
If you meant: refcount_dec(), but want the old value for tracing, you
want a different ordering than if you wanted to do
refcount_dec_and_test(); dec_return can't know this.
David, would something like a __refcount_*() API work where there is a
3rd argument (int *), which, if !NULL, will be assigned the old value?
next prev parent reply other threads:[~2020-07-21 19:51 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-12 18:34 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 [this message]
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
2020-08-27 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
2020-07-29 20:41 ` David Howells
2020-07-29 20:52 ` Kees Cook
2020-07-28 11:01 ` [PATCH 0/3] Convert nsproxy, groups, and creds to refcount_t David Howells
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