From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f198.google.com (mail-pg1-f198.google.com [209.85.215.198]) (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 DA5833EDE4A for ; Fri, 4 Sep 2026 22:05:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.198 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788559561; cv=none; b=fgyC/8gusF/hnIzyrAoqdf+biHtwsQPsHOBlpMxIENlbXZ4xzbiFIuol+43LK/yXAe+vQu6k03EwuYSVaNogpw6S5vJ2QqENHfkwx8p0EsNHv/rlHvuPFXAvrr5GnRrTvvMS7N5sIr4lcrZDS3GCSlAL0g+4vNZ3NnZlPPe9bh4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788559561; c=relaxed/simple; bh=JE+Mf/xZybCdcDrWOeIPFco24j81E98f9DvLgRBGZC0=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=I0XPuaIbp4orKwRXpmLbgH+NgRiQduN8TAFibm5Pr5EaXgLt7tbldECO1ZQPDQqqxzFJBGHKsMZBQaMqAhvSePHykrZM5yrkKbpoSZSTHabPSipoJjqFmBz28GTk50B2QeVGjiWYgVKhsUmWtW3NcwYEUSp7ZlEBJ7uU+jQ24IY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--skhawaja.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=J/y3n/eU; arc=none smtp.client-ip=209.85.215.198 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--skhawaja.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="J/y3n/eU" Received: by mail-pg1-f198.google.com with SMTP id 41be03b00d2f7-cc1c1cc5206so1780361a12.3 for ; Fri, 04 Sep 2026 15:05:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1788559559; x=1789164359; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:from:to:cc:subject:date:message-id:reply-to :content-type; bh=gFPQMsmC48q+wz7mUdVX+fcsDqeGsLw2XrmLniTg61k=; b=J/y3n/eUh0/+Dp3Qal/DofBuOXvReIq30m+RZwLwJBpbmsyzf4hvb9zzvuypmRQRgv 3yGvGKBubK3oMQ3YpoxRDdbbtFyUm3aUUsb9SaTVKHKgbZ1WYkuOqyKzixKx7nIAkPva Fu4F4IpVWCr49e8W4iPIaMd3FXxlWva7nHP9roh52ITKdwXuXVyXGK5je9Q0/buO66WK z1XaYIa0Q/HIpjQ91gTHn/WGnw5FS+cGiHlCVpKGBZsy6YXlnYOLvDqoT2VrY5/ntsBX 08VwD1hYlWeRZnkTAEZhVXZBo+K7TLPDNcbPfb5llGmZHvVq150vEjS018caY8NLMtoe V1yw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1788559559; x=1789164359; h=content-type: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:content-type; bh=gFPQMsmC48q+wz7mUdVX+fcsDqeGsLw2XrmLniTg61k=; b=cwwexnecMKvaqyZ1pKQkixi1/qvgyrNf9QR1Uqr+dr0UznQzV1rKwPoBDVPXFPEK2q HbZTG5SmhgeysYGplv2aU6YFTrzzcnTB8D0C6LAyFQ+Cjj1B8Oi2J/23X5kWV4vh0PVV ErhtWr+nQMoAZ9HZu5KA6MUxCN1szaf0YTEQ6tgDRv0d39aFkoIZs1ac705o3F7terAG 1iYnSyHZfv8i55AxlCcowXpUfZLX77Jh5zLLFVA9lLfulQtcH7GsX/TCuD1CV/Rh9XNb Anj645XOTTRHgBnuyTCn4DLOyKiOkBjFLS8jNNzSJdmS7fjanpVKmDjRiIpVNNhReqGq PQNQ== X-Forwarded-Encrypted: i=1; AKwUvBzGVV97hiK43eLn2V86pjbKVsHw3e++Q2GhvbxauIP9vZ59K7MPqAwBpfn451NXB6aS/Z43EA+0DkwKRLE=@vger.kernel.org X-Gm-Message-State: AFuF++kOWzhMS68aC4G4EodFrp0FHYW+hFK7z+VebH+yhGP8K1prVMwR HFWRI5p9xEtQ0J28wOEiMD4/lk8QJTKBPb6iW4ToSNwG+YyMExg3bc87wIasqr0faRN9qTrhgSl aoAI5jaxiQhKkPA== X-Received: from pfbhm10.prod.google.com ([2002:a05:6a00:670a:b0:859:a043:9ede]) (user=skhawaja job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:13a2:b0:858:6307:5f7d with SMTP id d2e1a72fcca58-86166dbb899mr12027017b3a.8.1788559558716; Fri, 04 Sep 2026 15:05:58 -0700 (PDT) Date: Fri, 4 Sep 2026 22:05:54 +0000 In-Reply-To: <20260904220555.589752-1-skhawaja@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260904220555.589752-1-skhawaja@google.com> X-Mailer: git-send-email 2.55.0.1003.g10538fe699-goog Message-ID: <20260904220555.589752-2-skhawaja@google.com> Subject: [PATCH 1/1] liveupdate: luo_file: Add documentation for dependencies From: Samiullah Khawaja To: Pasha Tatashin , Mike Rapoport , Pratyush Yadav , Alexander Graf Cc: Samiullah Khawaja , David Matlack , tarunsahu@google.com, open list , "open list:KEXEC HANDOVER (KHO)" , "open list:KEXEC HANDOVER (KHO)" Content-Type: text/plain; charset="UTF-8" Add documentation for dependencies between FDs preserved by File Handlers. This supplements the previously added liveupdate_get_token_outgoing() and liveupdate_get_file_incoming() internal APIs to allow File Handlers to resolve dependencies. Signed-off-by: Samiullah Khawaja --- kernel/liveupdate/luo_file.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/kernel/liveupdate/luo_file.c b/kernel/liveupdate/luo_file.c index dbae0715220b..0a4994377c98 100644 --- a/kernel/liveupdate/luo_file.c +++ b/kernel/liveupdate/luo_file.c @@ -91,6 +91,21 @@ * again later. If the issue cannot be resolved, these resources will be held * by LUO until the next live update cycle, at which point they will be * discarded. + * + * Dependencies: + * + * Preserved files may have dependencies on other files that also need to be + * preserved during a live update. A file handler can resolve these dependencies + * by querying the token of the dependency. That token can then be serialized + * and used to fetch the dependency during the retrieve() callback in the next + * kernel. + * + * Some of these dependencies can be resolved late during File Handler freeze() + * callback, but some of these might need resolution during File Handler + * preserve() callback based on the constraints such as immutability and + * performance. This introduces an order of preservation. Note that the order of + * preservation of dependencies can be safely relaxed later, but it cannot be + * enforced later. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt -- 2.55.0.1003.g10538fe699-goog