From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 233DE2FB0A1 for ; Tue, 2 Dec 2025 22:10:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764713433; cv=none; b=KuYF/oYkZi6v/IFkVriERjXQQMtEMCl23xOjpaa3GRrVdoa4z7hi7f38T8rcTUwqoLKX3RYrCwaEKq6ozQIKEXVfsBsY67pCFB2JgQiXcKmIsjqyiHEGZMSZXm7vfzseeixs8ukbXqrm7JlhDqb9DUWCO8GflsLu3x7MJPC8BXA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764713433; c=relaxed/simple; bh=TGiuINOy78DgOSScNKjEVrzTOvGLoF2lW+2DaF4nW6Q=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=UkulBXO8tShRNq2bCIrWKlUHQ8FvdPZ/akuVXZZw3wgPPDX9/hHwCUjyoK975gJzQFLqx5EzPp9uLDjQvj9ekdAvOy9PGBHqq/u1Fdbn1OWfviqkTTvVC1b2CUTlUaBIZPbbgt7uUWJnzkCPLTUXVEGUwHR/NtDPMlwa7y33H5U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=XVLeFcpU; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="XVLeFcpU" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1764713431; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=wF8onqTSydFf9NeQRKuX4lDngt1xHIbA7KxQuLsqkCE=; b=XVLeFcpUCp25k5HSt2YHIgPyJTUJpwyzyYBDN7Bmo0UvC9AsVaG/QA98nOe8O7cd3iwk/v fpfKgEQvjsshKL1cbZk2iDp78YEYV2njX1Tm2NDy4xwJl1SGNw5+/a2b1Jv4Mhsx56EnqD Zpjzx5ruJRsVyBDHLl1rJaHyzJbiYaM= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-361-5UX4dJqpMFKdVUOGxN7BeA-1; Tue, 02 Dec 2025 17:10:28 -0500 X-MC-Unique: 5UX4dJqpMFKdVUOGxN7BeA-1 X-Mimecast-MFC-AGG-ID: 5UX4dJqpMFKdVUOGxN7BeA_1764713426 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id A58D7180009D; Tue, 2 Dec 2025 22:10:25 +0000 (UTC) Received: from chopper.lan (unknown [10.22.80.109]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id B007919560A7; Tue, 2 Dec 2025 22:10:21 +0000 (UTC) From: Lyude Paul To: dri-devel@lists.freedesktop.org, rust-for-linux@vger.kernel.org, Alice Ryhl , Daniel Almeida , Danilo Krummrich , linux-kernel@vger.kernel.org Cc: David Airlie , Simona Vetter , Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?= , Benno Lossin , Andreas Hindborg , Trevor Gross , Asahi Lina , Shankari Anand Subject: [PATCH v6 1/8] rust/drm: Add gem::impl_aref_for_gem_obj! Date: Tue, 2 Dec 2025 17:03:27 -0500 Message-ID: <20251202220924.520644-2-lyude@redhat.com> In-Reply-To: <20251202220924.520644-1-lyude@redhat.com> References: <20251202220924.520644-1-lyude@redhat.com> Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 In the future we're going to be introducing more GEM object types in rust then just gem::Object. Since all types of GEM objects have refcounting, let's introduce a macro that we can use in the gem crate in order to copy this boilerplate implementation for each type: impl_aref_for_gem_obj!(). Signed-off-by: Lyude Paul Reviewed-by: Daniel Almeida --- V5: * Move .as_raw() call to `let obj` in dec_ref, to ensure that the reference to object is not live by the time that we call drm_gem_object_put(). * Add missing #[macro_export] annotation V6: * Add missing IntoGEMObject trait bound rust/kernel/drm/gem/mod.rs | 53 +++++++++++++++++++++++++++----------- 1 file changed, 38 insertions(+), 15 deletions(-) diff --git a/rust/kernel/drm/gem/mod.rs b/rust/kernel/drm/gem/mod.rs index a7f682e95c018..5c215e83c1b09 100644 --- a/rust/kernel/drm/gem/mod.rs +++ b/rust/kernel/drm/gem/mod.rs @@ -15,6 +15,43 @@ }; use core::{ops::Deref, ptr::NonNull}; +/// A macro for implementing [`AlwaysRefCounted`] for any GEM object type. +/// +/// Since all GEM objects use the same refcounting scheme. +#[macro_export] +macro_rules! impl_aref_for_gem_obj { + ( + impl $( <$( $tparam_id:ident ),+> )? for $type:ty + $( + where + $( $bind_param:path : $bind_trait:path ),+ + )? + ) => { + // SAFETY: All gem objects are refcounted + unsafe impl $( <$( $tparam_id ),+> )? $crate::types::AlwaysRefCounted for $type + where + Self: IntoGEMObject, + $( $( $bind_param : $bind_trait ),+ )? + { + fn inc_ref(&self) { + // SAFETY: The existence of a shared reference guarantees that the refcount is + // non-zero. + unsafe { bindings::drm_gem_object_get(self.as_raw()) }; + } + + unsafe fn dec_ref(obj: core::ptr::NonNull) { + // SAFETY: `obj` is a valid pointer to an `Object`. + let obj = unsafe { obj.as_ref() }.as_raw(); + + // SAFETY: The safety requirements guarantee that the refcount is non-zero. + unsafe { bindings::drm_gem_object_put(obj) }; + } + } + }; +} + +pub(crate) use impl_aref_for_gem_obj; + /// A type alias for retrieving a [`Driver`]s [`DriverFile`] implementation from its /// [`DriverObject`] implementation. /// @@ -252,21 +289,7 @@ extern "C" fn free_callback(obj: *mut bindings::drm_gem_object) { } } -// SAFETY: Instances of `Object` are always reference-counted. -unsafe impl crate::types::AlwaysRefCounted for Object { - fn inc_ref(&self) { - // SAFETY: The existence of a shared reference guarantees that the refcount is non-zero. - unsafe { bindings::drm_gem_object_get(self.as_raw()) }; - } - - unsafe fn dec_ref(obj: NonNull) { - // SAFETY: `obj` is a valid pointer to an `Object`. - let obj = unsafe { obj.as_ref() }; - - // SAFETY: The safety requirements guarantee that the refcount is non-zero. - unsafe { bindings::drm_gem_object_put(obj.as_raw()) } - } -} +impl_aref_for_gem_obj!(impl for Object where T: DriverObject); impl super::private::Sealed for Object {} -- 2.52.0