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Date: Wed, 29 Nov 2023 16:23:05 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: Alice Ryhl <aliceryhl@google.com>, Miguel Ojeda <ojeda@kernel.org>,
	Alex Gaynor <alex.gaynor@gmail.com>,
	Wedson Almeida Filho <wedsonaf@gmail.com>,
	Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>,
	=?iso-8859-1?Q?Bj=F6rn?= Roy Baron <bjorn3_gh@protonmail.com>,
	Benno Lossin <benno.lossin@proton.me>,
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	Christian Brauner <brauner@kernel.org>,
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	Arve =?iso-8859-1?B?SGr4bm5lduVn?= <arve@android.com>,
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	Kees Cook <keescook@chromium.org>,
	Thomas Gleixner <tglx@linutronix.de>, Daniel Xu <dxu@dxuuu.xyz>,
	linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org,
	linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 1/7] rust: file: add Rust abstraction for `struct file`
Message-ID: <20231129152305.GB23596@noisy.programming.kicks-ass.net>
References: <20231129-alice-file-v1-0-f81afe8c7261@google.com>
 <20231129-alice-file-v1-1-f81afe8c7261@google.com>
 <ZWdVEk4QjbpTfnbn@casper.infradead.org>
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In-Reply-To: <ZWdVEk4QjbpTfnbn@casper.infradead.org>

On Wed, Nov 29, 2023 at 03:13:22PM +0000, Matthew Wilcox wrote:

> > @@ -157,6 +158,12 @@ void rust_helper_init_work_with_key(struct work_struct *work, work_func_t func,
> >  }
> >  EXPORT_SYMBOL_GPL(rust_helper_init_work_with_key);
> >  
> > +struct file *rust_helper_get_file(struct file *f)
> > +{
> > +	return get_file(f);
> > +}
> > +EXPORT_SYMBOL_GPL(rust_helper_get_file);
> 
> This is ridiculous.  A function call instead of doing the
> atomic_long_inc() in Rust?

Yeah, I complained about something similar a while ago. And recently
talked to Boqun about this as well,

Bindgen *could* in theory 'compile' the inline C headers into (unsafe)
Rust, the immediate problem is that Rust has a wildly different inline
asm syntax (because Rust needs terrible syntax or whatever).

Boqun said it should all be fixable, but is a non-trivial amount of
work.