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Date: Mon, 3 Feb 2025 12:54:18 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Alice Ryhl <aliceryhl@google.com>
Cc: Miguel Ojeda <ojeda@kernel.org>, Boqun Feng <boqun.feng@gmail.com>,
	Gary Guo <gary@garyguo.net>,
	=?iso-8859-1?Q?Bj=F6rn?= Roy Baron <bjorn3_gh@protonmail.com>,
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	Will Deacon <will@kernel.org>, Waiman Long <longman@redhat.com>,
	rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] rust: sync: add wait_interruptible_freezable
Message-ID: <20250203115418.GB14028@noisy.programming.kicks-ass.net>
References: <20250130-condvar-freeze-v1-1-a91d5661d505@google.com>
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In-Reply-To: <20250130-condvar-freeze-v1-1-a91d5661d505@google.com>

On Thu, Jan 30, 2025 at 11:30:44AM +0000, Alice Ryhl wrote:
> Binder allows you to freeze a process where some of its threads are
> blocked on the Binder driver. To make this work, we need to pass
> TASK_FREEZABLE when going to sleep in the appropriate places. Thus, add
> a new method wait_interruptible_freezable for the condition variable so
> that sleeps where this is supported can be marked as such.

The constraint on freezable is that you must not hold locks. There is a
lockdep check for this in the code, but it would probably make sense to
teach Rust about this constraint as well, hmm?