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 DCEEFC6FD18 for ; Wed, 29 Mar 2023 10:55:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229554AbjC2Kzj (ORCPT ); Wed, 29 Mar 2023 06:55:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54860 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229501AbjC2Kzb (ORCPT ); Wed, 29 Mar 2023 06:55:31 -0400 Received: from fanzine2.igalia.com (fanzine2.igalia.com [213.97.179.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 31EF23C32 for ; Wed, 29 Mar 2023 03:55:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:Content-Type:In-Reply-To:From: References:Cc:To:Subject:MIME-Version:Date:Message-ID:Sender:Reply-To: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=eeKNNTaluB3jSL4ect8rCFF9mBvDp31l7Qb11QUW504=; b=OYVD1jd3ZMstpRUlyLr8dYIkqo luefwzcNrQ2RfrHlZoaLYqYNhaA3MPMxnkaPoonRLKI3mWN64SrR+b0S5xKA4ycw+ohKO3I39L75E 3jnzLZvN7tPmK4nUZJ6VX5VzVumBgl5nGTvyCniX1VeVdbk4SXPe/WderSkqQxmuRW6eFyYrPw1Ln pgEgeNCY6GL7wk9YVyJCx6SKfOq3ghMSjqJywtM9IVyODmLDFE2Rp0Q8fz0cSJjG98TRjFB0lIXVY CgdwvmPsvrDDAXtKSQnD+eFDhgURGzpcfns+b+U4qfn7ATD8EFK9+JdL9dJZvsGZAF9+t9u/a8jM2 P2xMzaCA==; Received: from [177.34.168.16] (helo=[192.168.0.3]) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_128_GCM:128) (Exim) id 1phTSH-000aFq-J7; Wed, 29 Mar 2023 12:55:01 +0200 Message-ID: Date: Wed, 29 Mar 2023 07:54:56 -0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.9.0 Subject: Re: [PATCH 2/2] drm: test: Fix 32-bit issue in drm_buddy_test Content-Language: en-US To: David Gow , =?UTF-8?Q?Lu=c3=ads_Mendes?= , =?UTF-8?Q?Christian_K=c3=b6nig?= , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Daniel Vetter , =?UTF-8?Q?Ma=c3=adra_Canal?= , Arthur Grillo Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org References: <20230329065532.2122295-1-davidgow@google.com> <20230329065532.2122295-2-davidgow@google.com> From: =?UTF-8?Q?Ma=c3=adra_Canal?= In-Reply-To: <20230329065532.2122295-2-davidgow@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/29/23 03:55, David Gow wrote: > The drm_buddy_test KUnit tests verify that returned blocks have sizes > which are powers of two using is_power_of_2(). However, is_power_of_2() > operations on a 'long', but the block size is a u64. So on systems where > long is 32-bit, this can sometimes fail even on correctly sized blocks. > > This only reproduces randomly, as the parameters passed to the buddy > allocator in this test are random. The seed 0xb2e06022 reproduced it > fine here. > > For now, just hardcode an is_power_of_2() implementation using > x & (x - 1). > > Signed-off-by: David Gow As we still didn't consolidate an implementation of is_power_of_2_u64(), Reviewed-by: Maíra Canal Best Regards, - Maíra Canal > --- > > There are actually a couple of is_power_of_2_u64() implementations > already around in: > - drivers/gpu/drm/i915/i915_utils.h > - fs/btrfs/misc.h (called is_power_of_two_u64) > > So the ideal thing would be to consolidate these in one place. > > > --- > drivers/gpu/drm/tests/drm_buddy_test.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/tests/drm_buddy_test.c b/drivers/gpu/drm/tests/drm_buddy_test.c > index f8ee714df396..09ee6f6af896 100644 > --- a/drivers/gpu/drm/tests/drm_buddy_test.c > +++ b/drivers/gpu/drm/tests/drm_buddy_test.c > @@ -89,7 +89,8 @@ static int check_block(struct kunit *test, struct drm_buddy *mm, > err = -EINVAL; > } > > - if (!is_power_of_2(block_size)) { > + /* We can't use is_power_of_2() for a u64 on 32-bit systems. */ > + if (block_size & (block_size - 1)) { > kunit_err(test, "block size not power of two\n"); > err = -EINVAL; > }