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 C3139C433EF for ; Mon, 18 Oct 2021 13:58:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AD0FA60F11 for ; Mon, 18 Oct 2021 13:58:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232589AbhJROA5 (ORCPT ); Mon, 18 Oct 2021 10:00:57 -0400 Received: from mail.kernel.org ([198.145.29.99]:38968 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233740AbhJRN7A (ORCPT ); Mon, 18 Oct 2021 09:59:00 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 207E361501; Mon, 18 Oct 2021 13:41:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1634564494; bh=vSKllmAoAxJEYAd7SNZSGjMWf2ruCZRmMu4m2CgWPNU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=X2SM+PuLD9Wb1f7nZbYzlC8YVmqOZz7pmPMlnAsSPFVV+pMhubsG6yZqcJU5oUwnF wAxDm7hGpSdRi4IwiW482rCyWTQ080g/W7+kkfDfakj058kjKrPjSj5Lr9neAo4ciS JaXqyQq020cdQ5x9K77zEOZIoY8PGYLWz93oZntc= 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 5.14 067/151] driver core: Reject pointless SYNC_STATE_ONLY device links Date: Mon, 18 Oct 2021 15:24:06 +0200 Message-Id: <20211018132342.869733806@linuxfoundation.org> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211018132340.682786018@linuxfoundation.org> References: <20211018132340.682786018@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 @@ -675,7 +675,8 @@ 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_INFERRED) != DL_FLAG_SYNC_STATE_ONLY) ||