From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f73.google.com (mail-wm1-f73.google.com [209.85.128.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 10A893451AB for ; Fri, 17 Oct 2025 13:10:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.73 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760706621; cv=none; b=rOViIz5H4+Epn++Tjko/w0J7/Srr8qW+J3hgNEpXMtRPn17XwiTRQeNfba9KOQY5gNxWNB5Dth6uHmpmTzSnx567+4uxjYUyYASnAMAm4BYrr1FWpAfHMO/pN4xJoQHnv00mKfJsCzl7drGULpuigMVkGcpD1eZE983OOq6MS1U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760706621; c=relaxed/simple; bh=EEnm10MyYA68jZvokqSZJ7WfWmlN6TZQC+epsXTbdnY=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=VYeNjaNIZDxQvVPU+fOWJYh2PT/0cb7bNSYQbq2WEKYVktWlSCJqyplkwO7s14yb+aiwjdfUK6fDQE34Wx6f2hBbKJghsH7t0gYTF1WEkq6B87azKhYLFeguMoDi7OndEIZoBQC07QKdZ6fk9JIAB0/tjy6rnqHG9szStde+umg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--aliceryhl.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=4yKyRtXL; arc=none smtp.client-ip=209.85.128.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--aliceryhl.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="4yKyRtXL" Received: by mail-wm1-f73.google.com with SMTP id 5b1f17b1804b1-471001b980eso12842445e9.1 for ; Fri, 17 Oct 2025 06:10:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1760706618; x=1761311418; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=DoKMhSsyXfCYMAzn+A2bSpqJRrRoIP0G76cRQo/jaDg=; b=4yKyRtXLt1e28eRbQC+4UoY7CddijifB+pHvv4PunRxXpNJbGNbTzW29kNIbcnNl12 /pfxM5O7yabXtqi9z4+c8LrYrP85Qq5vulVag4ozniNIzQokIEYMSXoL6hfE/2+2zr+H xkFKKrtsEqMWbjH9nVbbJJNXO8dISi9FbNWP3oYzI6HDERg32N1p4i60ezm2UoFcbCSN 6NVciX/t+vN0CcSXUfvSHANwQF2/qKoyPbLuN4d+6WCjfeLLogVcBF0GDKSzHRWbHYyy 3kENiOBd91BPd1Xg/dsLs1nJqI/M8UNBauCOKNlfz2fGPvWVqQM+skxIbTXyNFQuDHQQ ey0Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1760706618; x=1761311418; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=DoKMhSsyXfCYMAzn+A2bSpqJRrRoIP0G76cRQo/jaDg=; b=txwCFOWGTB3u8GYT5ev+cGaMXtj0Oe0H+I4qhqvjs2rpBvwU3qnPF07fOkZUUSbcEY fVcLROO+N+EaMhf5KIXj9/n8yFwYwvonddbvYzwVSo6IwWPtM0J6NcLjvej3/7tKaXaQ oLRIB/IEqwrRAMKRqD8cIVmzAxlwXRuRWilBhtrcIKkwIbp3O1AWi3MEiJlApEKJ6Pxv vu/jcvCzCeEQzC+QOwQ+KGf6nuHVegnSYyfNi2hPVOi0XhmRWApn8K5oP5cwtvGvpzzc 5yXJpHBkWJqKAOHJuZVSyUD/RX9qfJg7sQoRgWaUNe+7FiHKiiYINLKcdKGWfdtC4Jss ZW6g== X-Gm-Message-State: AOJu0YyoQNhKbq6Mc1zgxPlVDTkyEYnJTWt3ipwnLDMUb3+NcXcRCUAa W9sFBPJLY+DC44i0Ezi8g9wnZA7SB19ZEH4gy+c7w6Dseg6HGtMAcXqVJhL9meJKWPZ/GseDTS2 im/n80o2WTq+VenPUgA== X-Google-Smtp-Source: AGHT+IFiCznOq3jJbbGi+1Po7x6b9rs4AbbiNhIwAWz98uYVYGfItGbGzMFvBzl0siZ+LujshcHcrsGvZWg5Wc0= X-Received: from wmgg24.prod.google.com ([2002:a05:600d:18:b0:46f:aa50:d706]) (user=aliceryhl job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:8b8c:b0:46e:4287:a85e with SMTP id 5b1f17b1804b1-471178a4af1mr25882615e9.13.1760706618472; Fri, 17 Oct 2025 06:10:18 -0700 (PDT) Date: Fri, 17 Oct 2025 13:10:17 +0000 In-Reply-To: <20251016202044.2748678-1-lyude@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251016202044.2748678-1-lyude@redhat.com> Message-ID: Subject: Re: [PATCH] rust: drm/gem: Remove Object.dev From: Alice Ryhl To: Lyude Paul Cc: linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, dri-devel@lists.freedesktop.org, Danilo Krummrich , David Airlie , Simona Vetter , Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , "=?utf-8?B?QmrDtnJu?= Roy Baron" , Benno Lossin , Andreas Hindborg , Trevor Gross , Daniel Almeida , Asahi Lina , Shankari Anand Content-Type: text/plain; charset="utf-8" On Thu, Oct 16, 2025 at 04:18:58PM -0400, Lyude Paul wrote: > I noticed by chance that there's actually already a pointer to this in > struct drm_gem_object. So, no use in carrying this around! > > Signed-off-by: Lyude Paul > --- > rust/kernel/drm/gem/mod.rs | 11 +++-------- > 1 file changed, 3 insertions(+), 8 deletions(-) > > diff --git a/rust/kernel/drm/gem/mod.rs b/rust/kernel/drm/gem/mod.rs > index 30c853988b942..28d929edae267 100644 > --- a/rust/kernel/drm/gem/mod.rs > +++ b/rust/kernel/drm/gem/mod.rs > @@ -187,12 +187,10 @@ impl BaseObject for T {} > /// Invariants > /// > /// - `self.obj` is a valid instance of a `struct drm_gem_object`. > -/// - `self.dev` is always a valid pointer to a `struct drm_device`. > #[repr(C)] > #[pin_data] > pub struct Object { > obj: Opaque, > - dev: NonNull>, > #[pin] > data: T, > } > @@ -222,9 +220,6 @@ pub fn new(dev: &drm::Device, size: usize) -> Result> { > try_pin_init!(Self { > obj: Opaque::new(bindings::drm_gem_object::default()), > data <- T::new(dev, size), > - // INVARIANT: The drm subsystem guarantees that the `struct drm_device` will live > - // as long as the GEM object lives. > - dev: dev.into(), > }), > GFP_KERNEL, > )?; > @@ -247,9 +242,9 @@ pub fn new(dev: &drm::Device, size: usize) -> Result> { > > /// Returns the `Device` that owns this GEM object. > pub fn dev(&self) -> &drm::Device { > - // SAFETY: The DRM subsystem guarantees that the `struct drm_device` will live as long as > - // the GEM object lives, hence the pointer must be valid. > - unsafe { self.dev.as_ref() } > + // SAFETY: `struct drm_gem_object.dev` is initialized and valid for as long as the GEM > + // object lives. > + unsafe { drm::Device::from_raw((*self.as_raw()).dev) } The wording here and in the invariants could be improved to say that T::Driver is the right choice for the generic parameter. Alice