From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0DB20C433F5 for ; Mon, 18 Oct 2021 13:46:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E7AC2610C7 for ; Mon, 18 Oct 2021 13:46:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232185AbhJRNsp (ORCPT ); Mon, 18 Oct 2021 09:48:45 -0400 Received: from mail.kernel.org ([198.145.29.99]:39668 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233802AbhJRNpy (ORCPT ); Mon, 18 Oct 2021 09:45:54 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id BBD1A615A7; Mon, 18 Oct 2021 13:35:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1634564149; bh=UKDdUxN31Y2tH8koy/hpWWmQl4c59XphxhJdnBYZU/U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cW+jqD0kv9YG78cuViZYpjEiJdJg4DeH1NWt6LrIaRaNzf9NWbatELFXVZWSdk6Ff IyC32ovY2X5+lPqsYOVpJcxohqIthTPXtAh7CiZgnDhaEVibnAf1EdjU0lMPYmMrzg 9F/0cn+bbgIZnhdPAiSAXD6o4mDPkUOjA3h00dFY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ulf Hansson , "Rafael J. Wysocki" , Saravana Kannan Subject: [PATCH 5.10 050/103] driver core: Reject pointless SYNC_STATE_ONLY device links Date: Mon, 18 Oct 2021 15:24:26 +0200 Message-Id: <20211018132336.434618524@linuxfoundation.org> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211018132334.702559133@linuxfoundation.org> References: <20211018132334.702559133@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Saravana Kannan commit f729a592adb6760013c3e48622a5bf256b992452 upstream. SYNC_STATE_ONLY device links intentionally allow cycles because cyclic sync_state() dependencies are valid and necessary. However a SYNC_STATE_ONLY device link where the consumer and the supplier are the same device is pointless because the device link would be deleted as soon as the device probes (because it's also the consumer) and won't affect when the sync_state() callback is called. It's a waste of CPU cycles and memory to create this device link. So reject any attempts to create such a device link. Fixes: 05ef983e0d65 ("driver core: Add device link support for SYNC_STATE_ONLY flag") Cc: stable Reported-by: Ulf Hansson Reviewed-by: Rafael J. Wysocki Reviewed-by: Ulf Hansson Signed-off-by: Saravana Kannan Link: https://lore.kernel.org/r/20210929190549.860541-1-saravanak@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/base/core.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -549,7 +549,8 @@ struct device_link *device_link_add(stru { struct device_link *link; - if (!consumer || !supplier || flags & ~DL_ADD_VALID_FLAGS || + if (!consumer || !supplier || consumer == supplier || + flags & ~DL_ADD_VALID_FLAGS || (flags & DL_FLAG_STATELESS && flags & DL_MANAGED_LINK_FLAGS) || (flags & DL_FLAG_SYNC_STATE_ONLY && flags != DL_FLAG_SYNC_STATE_ONLY) ||