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Date:   Tue, 27 Sep 2022 16:51:50 +0300
From:   Konstantin Shelekhin <k.shelekhin@yadro.com>
To:     Miguel Ojeda <ojeda@kernel.org>
CC:     Linus Torvalds <torvalds@linux-foundation.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        <rust-for-linux@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linux-fsdevel@vger.kernel.org>, <patches@lists.linux.dev>,
        Jarkko Sakkinen <jarkko@kernel.org>,
        Alex Gaynor <alex.gaynor@gmail.com>,
        Wedson Almeida Filho <wedsonaf@google.com>,
        Gary Guo <gary@garyguo.net>, Matthew Bakhtiari <dev@mtbk.me>,
        Boqun Feng <boqun.feng@gmail.com>,
        =?iso-8859-1?Q?Bj=F6rn?= Roy Baron <bjorn3_gh@protonmail.com>
Subject: Re: [PATCH v10 08/27] rust: adapt `alloc` crate to the kernel
Message-ID: <YzL/9mlOHemaey2n@yadro.com>
References: <20220927131518.30000-1-ojeda@kernel.org>
 <20220927131518.30000-9-ojeda@kernel.org>
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On Tue, Sep 27, 2022 at 03:14:39PM +0200, Miguel Ojeda wrote:
[...]
> +    /// Tries to append an element to the back of a collection.
> +    ///
> +    /// # Examples
> +    ///
> +    /// ```
> +    /// let mut vec = vec![1, 2];
> +    /// vec.try_push(3).unwrap();
> +    /// assert_eq!(vec, [1, 2, 3]);
> +    /// ```
> +    #[inline]
> +    #[stable(feature = "kernel", since = "1.0.0")]
> +    pub fn try_push(&mut self, value: T) -> Result<(), TryReserveError> {
> +        if self.len == self.buf.capacity() {
> +            self.buf.try_reserve_for_push(self.len)?;
> +        }
> +        unsafe {
> +            let end = self.as_mut_ptr().add(self.len);
> +            ptr::write(end, value);
> +            self.len += 1;
> +        }
> +        Ok(())
> +    }
[...]

Not being able to pass GFP flags here kinda limits the scope of Rust in
kernel. I think that it must be supported in the final version that gets
in.