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t=1723637287; bh=NRLpSjB2blskWzdVEuxep7r6O7TWmeLLJ2opBFrnFXw=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=ognMeWYNbsL4Ndt/N31pW5AQ0q9LIvDwUJeJknGrwkDrZHNBoaSZmVAne8BbYc6WB 48NQI3du7WSrP2U/2M7lZ3k9XhoLRO+2m06aCKZqMZya6HPxQYBe2+ZypAcqeC+O11 UlxPJUCmXA2rH/xXm2uLLyjPXXOdX3yBkka8UpDqyoYu+I8jlRPtQf1q3ko6dT10su 9y6IvASp+/UKlyrEcpW9HJTKlVUFIo1lYVVDnqD967lmKHBunyQQ+5GffcbcT5c9zZ G0EKiHfUQZjvfAujTQ2b1rr/lRbx1FKSMnrfQg9xmqtAIpHrNxT9X4W18xFbGm37Ht jHfCGw/LVZLlw== Message-ID: <0f6c4fb3-039a-4dc6-a07c-980ca06ecbeb@kernel.org> Date: Wed, 14 Aug 2024 14:08:00 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 11/26] rust: alloc: remove `BoxExt` extension To: Dirk Behme Cc: ojeda@kernel.org, alex.gaynor@gmail.com, wedsonaf@gmail.com, boqun.feng@gmail.com, gary@garyguo.net, bjorn3_gh@protonmail.com, benno.lossin@proton.me, a.hindborg@samsung.com, aliceryhl@google.com, akpm@linux-foundation.org, daniel.almeida@collabora.com, faith.ekstrand@collabora.com, boris.brezillon@collabora.com, lina@asahilina.net, mcanal@igalia.com, zhiw@nvidia.com, cjia@nvidia.com, jhubbard@nvidia.com, airlied@redhat.com, ajanulgu@redhat.com, lyude@redhat.com, linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-mm@kvack.org References: <20240812182355.11641-1-dakr@kernel.org> <20240812182355.11641-12-dakr@kernel.org> From: Danilo Krummrich Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Stat-Signature: 8aq5uzz7s8pqc88rug74zswzs87sfg7z X-Rspamd-Queue-Id: DBBFC20017 X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1723637288-980485 X-HE-Meta: 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 mKMhIWUL wZW27VEs8OP/JwLBrPJgG2cHoIJfcqPOS17TJy2KZ5uhHClQDQ7mXiFe5O+fCs5OBoG1SmM/vKP58NZ25q8wiqFtos3yZrxHPUW2tZbBSZwnFmlEY3bjgsDJTI0C6rBWdLhtEwVRksrT0w8/8PFO5FGCrfRpd11cjGEQyswA/n0P1sTf/+ncF2lq4z5GS19MX+epybIUpNV6qAoz3oa0SfbqVNK5f6hC8XjyZMa2jxJwD3wjMH1jLFyK4siIW/avXICKg1aX5+EaRupRijaxZ4TMkSrklpvNAoURpmmLSshI804Td5kr4EY/3PC01unUyPaxj8n7aIfa9G6PfDanHVBocGJit+b+B0Rjr X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi Dirk, On 8/14/24 1:55 PM, Dirk Behme wrote: > On 12.08.2024 20:22, Danilo Krummrich wrote: >> Now that all existing `Box` users were moved to the kernel `Box` type, >> remove the `BoxExt` extension and all other related extensions. > I just noticed that in the recent 'rust-dev' branch we have a change which *adds* something to BoxExt: > > rust: kernel: add drop_contents to BoxExt > https://github.com/Rust-for-Linux/linux/commit/62c34da1da6c01a635ea2308cb42996d0571059e > > I'm unclear how relevant that is. Just want to mention this in case it would make sense to include that directly in this patch series to avoid a future add-on patch ;) Thanks for reporting. I'm aware of this patch, we expect it to land before this series. I'll add `drop_contents` once I rebase onto it. - Danilo > > Thanks, > > Dirk > > P.S.: It looks like anything like this at least makes the compiler happy: > > diff --git a/rust/kernel/alloc/kbox.rs b/rust/kernel/alloc/kbox.rs > index d67f975502246..e91d441835d54 100644 > --- a/rust/kernel/alloc/kbox.rs > +++ b/rust/kernel/alloc/kbox.rs > @@ -9,6 +9,7 @@ >  use core::mem::MaybeUninit; >  use core::ops::{Deref, DerefMut}; >  use core::pin::Pin; > +use core::ptr; >  use core::ptr::NonNull; >  use core::result::Result; > > @@ -270,6 +271,28 @@ pub fn new_uninit(flags: Flags) -> Result, A>, AllocError> { >          Ok(Box(ptr, PhantomData::)) >      } > > +    /// Drops the contents, but keeps the allocation. > +    /// > +    /// # Examples > +    /// > +    /// ``` > +    /// use kernel::alloc::{Flags, KBox}; > +    /// let value = KBox::new([0; 32], GFP_KERNEL)?; > +    /// assert_eq!(*value, [0; 32]); > +    /// let value = KBox::drop_contents(value); > +    /// // Now we can re-use `value`: > +    /// let value = KBox::write(value, [1; 32]); > +    /// assert_eq!(*value, [1; 32]); > +    /// # Ok::<(), Error>(()) > +    /// ``` > +    pub fn drop_contents(this: Self) -> Box, A> { > +        let ptr = Box::into_raw(this); > +        // SAFETY: `ptr` is valid, because it came from `Box::into_raw`. > +        unsafe { ptr::drop_in_place(ptr) }; > +        // SAFETY: `ptr` is valid, because it came from `Box::into_raw`. > +        unsafe { Box::from_raw(ptr.cast()) } > +    } > + >      /// Constructs a new `Pin>`. If `T` does not implement [`Unpin`], then `x` will be >      /// pinned in memory and can't be moved. >      #[inline]