From: "Gary Guo" <gary@garyguo.net>
To: <paulmck@kernel.org>, "Philipp Stanner" <phasta@kernel.org>
Cc: "Miguel Ojeda" <ojeda@kernel.org>,
"Boqun Feng" <boqun@kernel.org>, "Gary Guo" <gary@garyguo.net>,
"Björn Roy Baron" <bjorn3_gh@protonmail.com>,
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linaro-mm-sig@lists.linaro.org, rcu@vger.kernel.org
Subject: Re: [PATCH v7 3/5] rust: sync: Add abstraction for rcu_barrier()
Date: Wed, 29 Jul 2026 19:47:46 +0100 [thread overview]
Message-ID: <DKBA29HOEUIX.H4CDPOQQXRD0@garyguo.net> (raw)
In-Reply-To: <296c71c4-4d2f-416d-bfbe-40fd911b44db@paulmck-laptop>
On Wed Jul 29, 2026 at 6:18 PM BST, Paul E. McKenney wrote:
> On Wed, Jul 29, 2026 at 11:45:40AM +0200, Philipp Stanner wrote:
>> rcu_barrier() is a frequently used C function which is always safe to be
>> called.
>
> Just checking... Here "always safe" means only from task level, with BH,
> preemption, and interrupts all enabled, correct?
>
> In contrast, if you do this:
>
> preempt_disable();
> rcu_barrier();
> preempt_enable();
>
> the results won't be safe.
This is same for all sleepable functions. In order to avoid having to mark all
sleeping function unsafe, we've decided that sleeping from non-preemptable
context is "safe", but is a bug regardless.
Best,
Gary
next prev parent reply other threads:[~2026-07-29 18:47 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-29 9:45 [PATCH v7 0/5] rust / dma_buf: Add abstractions for dma_fence Philipp Stanner
2026-07-29 9:45 ` [PATCH v7 1/5] rust: error: add remaining error codes Philipp Stanner
2026-07-29 9:45 ` [PATCH v7 2/5] rust: types: implement ForeignOwnable for ARef<T> Philipp Stanner
2026-07-29 9:45 ` [PATCH v7 3/5] rust: sync: Add abstraction for rcu_barrier() Philipp Stanner
2026-07-29 17:18 ` Paul E. McKenney
2026-07-29 18:47 ` Gary Guo [this message]
2026-07-29 18:58 ` Paul E. McKenney
2026-07-29 9:45 ` [PATCH v7 4/5] rust: Add dma_fence abstractions Philipp Stanner
2026-07-29 9:45 ` [PATCH v7 5/5] MAINTAINERS: Add entry for Rust dma-buf Philipp Stanner
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