From: David Howells <dhowells@redhat.com>
To: Will Deacon <will@kernel.org>
Cc: dhowells@redhat.com, peterz@infradead.org,
Kees Cook <keescook@chromium.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
Subject: Re: [RFC][PATCH] locking/refcount: Provide __refcount API to obtain the old value
Date: Tue, 26 Jan 2021 11:25:39 +0000 [thread overview]
Message-ID: <2697076.1611660339@warthog.procyon.org.uk> (raw)
In-Reply-To: <20200921112218.GB2139@willie-the-truck>
Will Deacon <will@kernel.org> wrote:
> > @@ -219,9 +235,14 @@ static inline void refcount_add(int i, r
> > *
> > * Return: true if the increment was successful, false otherwise
> > */
> > +static inline __must_check bool __refcount_inc_not_zero(refcount_t *r, int *oldp)
> > +{
> > + return __refcount_add_not_zero(1, r, oldp);
> > +}
>
> Where returning both a bool to indicate whether the old value was zero
> and also the old value itself is a bit OTT.
Actually, with the i386 cmpxchg, that makes sense. You can use the Z flag to
give you the bool, saving on checking the old value.
David
next prev parent reply other threads:[~2021-01-26 11:46 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
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 [this message]
2020-07-28 11:01 ` [PATCH 0/3] Convert nsproxy, groups, and creds to refcount_t David Howells
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