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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D5CA4C433EF for ; Wed, 23 Feb 2022 10:56:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239470AbiBWK4k (ORCPT ); Wed, 23 Feb 2022 05:56:40 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33298 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236233AbiBWK4j (ORCPT ); Wed, 23 Feb 2022 05:56:39 -0500 Received: from out5-smtp.messagingengine.com (out5-smtp.messagingengine.com [66.111.4.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7FB447D03D for ; Wed, 23 Feb 2022 02:56:12 -0800 (PST) Received: from compute1.internal (compute1.nyi.internal [10.202.2.41]) by mailout.nyi.internal (Postfix) with ESMTP id C157F5C01E5; Wed, 23 Feb 2022 05:56:11 -0500 (EST) Received: from mailfrontend1 ([10.202.2.162]) by compute1.internal (MEProxy); Wed, 23 Feb 2022 05:56:11 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cerno.tech; h=cc :cc:content-transfer-encoding:date:date:from:from:in-reply-to :in-reply-to:message-id:mime-version:references:reply-to:sender :subject:subject:to:to; s=fm2; bh=IW+mV/sYomA7p2iMVLnrfnt2OPuKxa e7vUhcazyHY+o=; b=GXnbgt4ODeR89FwIuyZpdd3+E49oWVXRokGX+V8bhi9Eyi E4O28Z7rgF2JNpyi65QFaiXJr0Tjq46c13WD4zOW1oiyfCsRIa80PKEcFJQv6DPq g7D/D3YuPfHIeCE0G1Sv+BLlETjEC9JDaB0V3RSkSYDAmH2wtmg7IwqmtUI7GEqP depImrfjDilJPIFx/aYgL2jzHLweIql0JgD1JnsE6whpnzdDkLlxU+OxzSul9B3J XP7cyqa3AUSJo4nu04BiyoY7QMgO9p5fPA6KHBd/MBLOpY/dtFIPwI1vr9nvCuMo T3lt63Cwtrnf+5a94yAeSg+FkxR4U/hTlAxNHx2Q== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-transfer-encoding:date:date :from:from:in-reply-to:in-reply-to:message-id:mime-version :references:reply-to:sender:subject:subject:to:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm2; bh=IW+mV/ sYomA7p2iMVLnrfnt2OPuKxae7vUhcazyHY+o=; b=oyidOVBxUnEWYZTz82HE8v b9JUILdh3NGtM/ANZ2+lVdAHTTADZN0fd8RMRlmy4aHSuHUxswmiRULxgpeqDppo qQmxxgKefPaPrQEboXAygyAWfDVVkHZFGi3dqhIBW0Kfym/FwEnL5+1cqYsZCCui Mt4ZyAKE0u3MPcgiqN+PamPnM4zxnDNq3N/C0tYCNPJPZ9DN34DJezDsP8XGIYh1 5If7fYVsVf5ySZf34MLFzLgWRm8ASaFneiE5cNd2PlM86+9Gt2q7YD/Kc9i3E9u4 1vl+OO06lJWgRfAJKA0u1dMWazPcH+rasSltfcK56Na+clmgrxYdFZYhtRa9NzVA == X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvvddrledtgddvudcutefuodetggdotefrodftvf curfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfghnecu uegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenuc fjughrpefhvffufffkofgjfhgggfestdekredtredttdenucfhrhhomhepofgrgihimhgv ucftihhprghrugcuoehmrgigihhmvgestggvrhhnohdrthgvtghhqeenucggtffrrghtth gvrhhnpedvkeelveefffekjefhffeuleetleefudeifeehuddugffghffhffehveevheeh vdenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpehmrg igihhmvgestggvrhhnohdrthgvtghh X-ME-Proxy: Received: by mail.messagingengine.com (Postfix) with ESMTPA; Wed, 23 Feb 2022 05:56:11 -0500 (EST) From: Maxime Ripard To: Mike Turquette , Stephen Boyd Cc: linux-clk@vger.kernel.org, Dave Stevenson , Phil Elwell , Tim Gover , Dom Cobley , dri-devel@lists.freedesktop.org, Maxime Ripard Subject: [PATCH v6 03/12] clk: Enforce that disjoints limits are invalid Date: Wed, 23 Feb 2022 11:55:51 +0100 Message-Id: <20220223105600.1132593-4-maxime@cerno.tech> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220223105600.1132593-1-maxime@cerno.tech> References: <20220223105600.1132593-1-maxime@cerno.tech> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-clk@vger.kernel.org If we were to have two users of the same clock, doing something like: clk_set_rate_range(user1, 1000, 2000); clk_set_rate_range(user2, 3000, 4000); The second call would fail with -EINVAL, preventing from getting in a situation where we end up with impossible limits. However, this is never explicitly checked against and enforced, and works by relying on an undocumented behaviour of clk_set_rate(). Indeed, on the first clk_set_rate_range will make sure the current clock rate is within the new range, so it will be between 1000 and 2000Hz. On the second clk_set_rate_range(), it will consider (rightfully), that our current clock is outside of the 3000-4000Hz range, and will call clk_core_set_rate_nolock() to set it to 3000Hz. clk_core_set_rate_nolock() will then call clk_calc_new_rates() that will eventually check that our rate 3000Hz rate is outside the min 3000Hz max 2000Hz range, will bail out, the error will propagate and we'll eventually return -EINVAL. This solely relies on the fact that clk_calc_new_rates(), and in particular clk_core_determine_round_nolock(), won't modify the new rate allowing the error to be reported. That assumption won't be true for all drivers, and most importantly we'll break that assumption in a later patch. It can also be argued that we shouldn't even reach the point where we're calling clk_core_set_rate_nolock(). Let's make an explicit check for disjoints range before we're doing anything. Signed-off-by: Maxime Ripard --- drivers/clk/clk.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index fff5edb89d6d..112911138a7b 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -632,6 +632,24 @@ static void clk_core_get_boundaries(struct clk_core *core, *max_rate = min(*max_rate, clk_user->max_rate); } +static bool clk_core_check_boundaries(struct clk_core *core, + unsigned long min_rate, + unsigned long max_rate) +{ + struct clk *user; + + lockdep_assert_held(&prepare_lock); + + if (min_rate > core->max_rate || max_rate < core->min_rate) + return false; + + hlist_for_each_entry(user, &core->clks, clks_node) + if (min_rate > user->max_rate || max_rate < user->min_rate) + return false; + + return true; +} + void clk_hw_set_rate_range(struct clk_hw *hw, unsigned long min_rate, unsigned long max_rate) { @@ -2348,6 +2366,11 @@ int clk_set_rate_range(struct clk *clk, unsigned long min, unsigned long max) clk->min_rate = min; clk->max_rate = max; + if (!clk_core_check_boundaries(clk->core, min, max)) { + ret = -EINVAL; + goto out; + } + rate = clk_core_get_rate_nolock(clk->core); if (rate < min || rate > max) { /* @@ -2376,6 +2399,7 @@ int clk_set_rate_range(struct clk *clk, unsigned long min, unsigned long max) } } +out: if (clk->exclusive_count) clk_core_rate_protect(clk->core); -- 2.35.1