Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <a1a57732-6b1c-5572-e59f-ca5e33c5a323@amd.com>
Date:   Wed, 29 Mar 2023 15:14:56 +0200
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:     Jani Nikula <jani.nikula@linux.intel.com>,
        =?UTF-8?Q?Ma=c3=adra_Canal?= <mcanal@igalia.com>,
        David Gow <davidgow@google.com>,
        =?UTF-8?Q?Lu=c3=ads_Mendes?= <luis.p.mendes@gmail.com>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Maxime Ripard <mripard@kernel.org>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        =?UTF-8?Q?Ma=c3=adra_Canal?= <mairacanal@riseup.net>,
        Arthur Grillo <arthurgrillo@riseup.net>
Cc:     linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org
References: <20230329065532.2122295-1-davidgow@google.com>
 <20230329065532.2122295-2-davidgow@google.com>
 <ceb0b1e8-6c7a-8564-156f-fcf0f0e4a95e@igalia.com> <87fs9n4x02.fsf@intel.com>
From:   =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@amd.com>
In-Reply-To: <87fs9n4x02.fsf@intel.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?Z0s2RHhDdHZEcHQ0NVQrTVVWbjgwOHdHYXY3YUUyOTJmbkQ5NVFHekZxMFBH?=
 =?utf-8?B?ZWxpb2M0ZmNMcTF2L0hvYyt1cDBOZzlWRzUyMlZiSGEvNHVwQVovNVhXMVN2?=
 =?utf-8?B?YmpUTGVTdXJiVmdORzJVNjQ5QURvUmVpS0FvVERyQU05NEZlaGVmazlrK1ZO?=
 =?utf-8?B?bUk3V0R2QTE1WThmcXN6K0JSQmFJWDVxZmd0TW8zSFc2TW8zNXM5dWx1czNT?=
 =?utf-8?B?NzhaQm9tVFZCVnA4dHh3WXJaZWhXalViVlQzdFlvV04vTW10QWhjM2NnVGQw?=
 =?utf-8?B?SVI3ejIwbEYwQXZXeXlqc0NJb1JvV0RIeGo2aXlzcmhxQ2JKYWJ1ZVpTVTht?=
 =?utf-8?B?NENQSFU1V2p0UmprNkVtTTBKaCs3MVVaNmlJRGRpNG5RcWFUaTFlamR2VFI5?=
 =?utf-8?B?eUlTaGZBbWY1b05ubm51MjExY2FDa2NCbVhUczRYdDBrUzlTQ3JQOXFiUHpB?=
 =?utf-8?B?ODVUa3dKZCt6a1lqeEZFYzh2UjV1N3hjWlFXMnRYZ0FaanF3NWdSSmtpcS9z?=
 =?utf-8?B?WEgzc0tsTFE1QVpzRkxDeUx5VFBsMnVhT25EQ1VrMWsrRFRLOGN4ZHozQVVP?=
 =?utf-8?B?VDRndzRuM0xmWDNsT052bkxwUDlOdjk0Nk42TzI4cnp3NW1kZWdpK0xMUWZm?=
 =?utf-8?B?a2lxRkZvQzNnRHJhQ1ErOWljWDVTWUhQKzFGTU9hWDZrdWZQeWxBazhtbEpt?=
 =?utf-8?B?MmFkeU1QbHRZVUFxUEM3bURJYVRZbkhuZForWEJsSlhFZjZ1dEVIb2tiU3cv?=
 =?utf-8?B?RUp1dmJQcXVTWS9EMGNnODZWSmgzbUxFSys0ZU9nTGM1bjB4eUZreVh5V1Qr?=
 =?utf-8?B?YnozNWhhL1E4V3JSWVhkbVVjZGxRQUZpZFRwSUx5eURBeEFMTWFNbHMvWXpa?=
 =?utf-8?B?SVFwcXQ2Z2Vham45eHFHMkUyUjlIckNDTnlORW1BQ0JmaTBTQmRaeG83UjQx?=
 =?utf-8?B?WGpOY1NjaVd0OU8rWTcyNUs2Zm9yODNRb2JrVk1NQ1hwcDVBRjNsa09XVW4y?=
 =?utf-8?B?YnFnV0lrU0VJbFpnL25udGhLL2JNNVRFTlhVUndKSmIrL2NLS2t0TXFuaEc1?=
 =?utf-8?B?cnRSbi9qSU1jNE8rSHFCdFRDMWQ4ZXh2S0Y4ZThoOEJCOU9hUXpyRDlqMUw2?=
 =?utf-8?B?WVM1UDRkV1BidVdXNENFdVdsYlQ0bzZWS1V1SWFlaHV0K2Y3T0I2aFVJZ0FF?=
 =?utf-8?B?Q0VGalYvZ1FIUlh6bUNhVXVkVWhNMWl0cmpBQnI3QkdISGlUcWkyZStia2Nz?=
 =?utf-8?B?OEpDSUJWOWg5ZHcvdHRKWE1Hanc0K3NtZDh2NGg3cVRrZ0pWSnZVZEoyeXNp?=
 =?utf-8?B?ME9SckZTVk9BVnprRFM0NEdpd0loaHBLMENPNEt1d0NPdkxEVXY1OGZBckQ4?=
 =?utf-8?B?dEtoNEtYeDJDZzVQUTU4c3pCNXIvWTRiNVNqNXp3RzRXYzQyM3pUUmdwNTFW?=
 =?utf-8?B?OUk0b0UwUDBxazNIejVmdTlqUURMbzRqQ01waUhDUzJJNEpjWTVlUit5WUVk?=
 =?utf-8?B?bW1tOTg4L25XUmVwYWhhNkpEa1lJbTYxS2ppakRjZ3pPNEM2NnlwVTZXbHFs?=
 =?utf-8?B?U2hUMFpsSFVZVlFRalRTdUFmUnVYV3ArcmZBYWFpUDlZa3VKSHBwNWkzcWdI?=
 =?utf-8?B?b3FyWnhVcjFmaTNzWHJhNEtBemwzcVZMWW1WU3QvVkFnM3FiZDBrbVlMQ0NS?=
 =?utf-8?B?Sjk4ZDB6ak42SGxVc1dwV3Y3c2owOUxrYmcxZ24zdWRZcXM4aGpxa1h3TmNY?=
 =?utf-8?B?NjdrSXJ5UlJ5NUpqdnIxdTYyaHBWWTJma2paREdxVHV3UVRaU2FHcEtXSGhz?=
 =?utf-8?B?Qm1kUWZ1ZnZDc3VISE5mZjlrelg4dkluenZ1UzVDbVlMSG04WTdYSThSdU9q?=
 =?utf-8?B?Kzlsbk9TL1p5WWI5eE00TlF6QmRvZnNFd0lodVgvRlo0MXJqejhpWGNITUR5?=
 =?utf-8?B?U0RTVGkramVnR283SWtiUGFTaDdkVVV5ZDVJNDVOOUlJMzdydTFVSFhPZWdi?=
 =?utf-8?B?YVV0OVFMQitJZTRBejBFeldFbnNuOVBNNlpyUTBJSWZNUEdVMUZpUE03M05k?=
 =?utf-8?B?U1oxODM5WTBMenQ3bmpIZ29KQXVkaW95UU8rbzJmMG1YNldzaUhib2xWcUN0?=
 =?utf-8?B?VDdLZy9FYlhWMStPTDh1UmdkSkU5YnpncHZRelFtNlB3eHVlMDRUaG9WMWtF?=
 =?utf-8?Q?nBr+3j8suCxVdWIdMsE1RvhPmBD+6RcOHQKxZyaGKJpt?=
X-OriginatorOrg: amd.com
X-MS-Exchange-CrossTenant-Network-Message-Id: e6dffee3-e5e4-48d2-59fe-08db30579b18
X-MS-Exchange-CrossTenant-AuthSource: BN8PR12MB3587.namprd12.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 29 Mar 2023 13:15:02.6855
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: k9B824B9nyLHQmaMYzg8ULXDg9QeL5RvvM/gaoPRje+MxLb7+F/wzHeHht1YG3wB
X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR12MB5392
X-Spam-Status: No, score=-0.2 required=5.0 tests=DKIM_SIGNED,DKIM_VALID,
        DKIM_VALID_AU,DKIM_VALID_EF,FORGED_SPF_HELO,NICE_REPLY_A,
        RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,SPF_NONE
        autolearn=unavailable autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Am 29.03.23 um 13:28 schrieb Jani Nikula:
> On Wed, 29 Mar 2023, Maíra Canal <mcanal@igalia.com> wrote:
>> 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 <davidgow@google.com>
>> As we still didn't consolidate an implementation of is_power_of_2_u64(),
> I just cooked up some patches to try to make is_power_of_2() more
> flexible. I only sent them to the "CI trybot" for a quick spin first,
> will post to lkml later. [1]

In the meantime I'm pushing this to drm-misc-fixes unless somebody has 
some last second objections.

Christian.

>
> BR,
> Jani.
>
>
> [1] https://patchwork.freedesktop.org/series/115785/
>
>> Reviewed-by: Maíra Canal <mcanal@igalia.com>
>>
>> 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;
>>>    	}