From: "Paul E. McKenney" <paulmck@kernel.org>
To: Jonas Oberhauser <jonas.oberhauser@huaweicloud.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Boqun Feng <boqun.feng@gmail.com>,
lkmm@lists.linux.dev
Subject: Re: [RFC PATCH 1/1] hpref: Hazard Pointers with Reference Counter
Date: Tue, 1 Oct 2024 08:24:01 -0700 [thread overview]
Message-ID: <c0c83773-2c9b-4cfa-a28e-dec410f1b35a@paulmck-laptop> (raw)
In-Reply-To: <13bc8b46-d391-4f58-b021-481e57d2ac1f@huaweicloud.com>
On Mon, Sep 30, 2024 at 03:31:02PM +0200, Jonas Oberhauser wrote:
> [dropping a lot of CC]
>
> Am 9/21/2024 um 6:42 PM schrieb Mathieu Desnoyers:
> >
> > Porting it to the Linux kernel should be straightforward.
>
>
> Btw, what is the relation between uatomics and LKMM?
>
> Should I assume that they intend to have LKMM semantics modulo whatever is
> explained here:
>
> https://github.com/urcu/userspace-rcu/blob/master/doc/uatomic-api.md
>
> Because on C11 model, dependencies are generally not considered
I must defer to Mathieu for recent uatomic directions, but the original
idea was to follow LKMM.
You are right that C11 compilers and memory model don't do much with
dependencies, one exception being the "don't create data races" rule
which requires that non-atomic accesses protected by "if" statements
stay protected, at least in the absence of a nearby unprotected access
to that same variable.
So if uatomic is to rely on dependencies, it must use the same tricks
as LKMM does, including code-style restrictions.
Thanx, Paul
next prev parent reply other threads:[~2024-10-01 15:24 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-09-21 16:42 [RFC PATCH 1/1] hpref: Hazard Pointers with Reference Counter Mathieu Desnoyers
2024-09-21 21:07 ` Lai Jiangshan
2024-09-22 7:47 ` Mathieu Desnoyers
2024-09-25 5:57 ` Jonas Oberhauser
2024-09-25 6:35 ` Mathieu Desnoyers
2024-09-25 10:06 ` Jonas Oberhauser
2024-09-25 11:36 ` Mathieu Desnoyers
2024-09-25 12:02 ` Jonas Oberhauser
2024-09-28 11:22 ` Jonas Oberhauser
2024-09-28 11:33 ` Mathieu Desnoyers
2024-09-28 11:50 ` Jonas Oberhauser
2024-09-30 13:31 ` Jonas Oberhauser
2024-10-01 15:24 ` Paul E. McKenney [this message]
2026-01-06 14:52 ` Mathieu Desnoyers
2026-01-07 9:38 ` Jonas Oberhauser
2026-01-07 14:40 ` Mathieu Desnoyers
2026-01-07 17:48 ` Paul E. McKenney
2026-01-07 20:04 ` Mathieu Desnoyers
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