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: <ce79b696-339b-3505-5884-14a20489de57@amd.com>
Date:   Wed, 24 Aug 2022 16:09:55 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Thunderbird/91.11.0
Subject: Re: [PATCH v3 9/9] dma-buf: Remove internal lock
Content-Language: en-US
To:     Dmitry Osipenko <dmitry.osipenko@collabora.com>,
        David Airlie <airlied@linux.ie>,
        Gerd Hoffmann <kraxel@redhat.com>,
        Gurchetan Singh <gurchetansingh@chromium.org>,
        Chia-I Wu <olvaffe@gmail.com>, Daniel Vetter <daniel@ffwll.ch>,
        Daniel Almeida <daniel.almeida@collabora.com>,
        Gert Wollny <gert.wollny@collabora.com>,
        Gustavo Padovan <gustavo.padovan@collabora.com>,
        Daniel Stone <daniel@fooishbar.org>,
        Tomeu Vizoso <tomeu.vizoso@collabora.com>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Maxime Ripard <mripard@kernel.org>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        Rob Clark <robdclark@gmail.com>,
        Sumit Semwal <sumit.semwal@linaro.org>,
        "Pan, Xinhui" <Xinhui.Pan@amd.com>,
        Thierry Reding <thierry.reding@gmail.com>,
        Tomasz Figa <tfiga@chromium.org>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Alex Deucher <alexander.deucher@amd.com>,
        Jani Nikula <jani.nikula@linux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@intel.com>,
        Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
        =?UTF-8?Q?Thomas_Hellstr=c3=b6m?= <thomas_os@shipmail.org>,
        Qiang Yu <yuq825@gmail.com>
Cc:     dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        Dmitry Osipenko <digetx@gmail.com>,
        linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org,
        amd-gfx@lists.freedesktop.org, intel-gfx@lists.freedesktop.org,
        kernel@collabora.com, virtualization@lists.linux-foundation.org,
        linux-rdma@vger.kernel.org, linux-arm-msm@vger.kernel.org,
        lima@lists.freedesktop.org
References: <20220824102248.91964-1-dmitry.osipenko@collabora.com>
 <20220824102248.91964-10-dmitry.osipenko@collabora.com>
From:   =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@amd.com>
In-Reply-To: <20220824102248.91964-10-dmitry.osipenko@collabora.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?RHZvZkdGS242YVZNUWVVU0x0d1dTYi90OXFsUW5vN3U2aERzQ3ArMFdpUy9q?=
 =?utf-8?B?aXdKaHVOTGhRTUgrMnNiWFNNRWxWai9hbWdEL1ZFV1FTWUZzYkltUkVtZTNE?=
 =?utf-8?B?UWV3Q2t5R1BYMGE3WFJZN2NtQ1BXaTU4RkJMbUF2Z1Nxc2tMNy9NRHFLN2hJ?=
 =?utf-8?B?K3BJWnVqaU5JS1lsOVl0UlIwd0w5bjFNNkpWZWNDZ3hCbkcyc04wR0VLSjdo?=
 =?utf-8?B?TXBiRFVMcWI4S2swSk1YVks1K0ZPSkZwVkJZbUhUSzR3anpWdTV1Z21ZRlJC?=
 =?utf-8?B?OS9xeXFZT1VYWnh5dWxaMERpaXdEd1NvUThpUG4xQ1R1SjJFRXIzQVBNRjFn?=
 =?utf-8?B?Mm5GaVg1ZjBXVk1BSm1yMlV2ZGNCekEram9LRXJScGsxeDZqVGZaUFRSTG5m?=
 =?utf-8?B?dU9PU01YU0FkTVhsZDZ5RzNEOGtCQ2t5VzhzQUFUK0prNmFSTGtyVjRCK0Y3?=
 =?utf-8?B?emNIakUxTXM2dWlBT2FFNGJHc3NCSXM3L3NybndiYmRmdmpZb0ZtNVlLVTFZ?=
 =?utf-8?B?YmorQmZRU1NLU1g3ZXJiaXRqTjVDZjNrcVB3USswdFRMVndJVHJpcFdZckRv?=
 =?utf-8?B?UEVVRFg1YlFQbEM2Nm4rVmNsaFl4a3grVXJsVGprQU9PR20xTmRyOU8rSkgw?=
 =?utf-8?B?MWxFbFlvSVI2T3dQWGRCWVZvSHRLb1FzWHdwL2lPUVV0VExmUVpjY3hJSGtQ?=
 =?utf-8?B?cCtKVHZ6REM5ZEdSdTNEdnhtcmxQWjNrMThhYzVQNTdqc0tuUEs0d2hsL2ky?=
 =?utf-8?B?cGxuSTd5SlIwYysrR1A0V1RKK2dYRnpvQ0RMMFl5M0NaalhqZmlPd2FYLzAw?=
 =?utf-8?B?dGxyZWtPUHhrSlBUOFZtQk5UOThNMkg2MzF6Z2dpd1NUODlIUzA4ZUJRd3Zy?=
 =?utf-8?B?d0JHNVR0cWNSYW1qSFdscWNYZ3ZIWVRhcm82Ymc1VzZ2Znh0VEVPQkJDTWVy?=
 =?utf-8?B?TUhNclNkcEdjN3ErT3g4NTBuNnVSQ0tQb3NTQUJqQnFaN3NNSUVXVjJSYkRQ?=
 =?utf-8?B?b0JiS3BHSUw3WHNRajlVbHUrUWRuczFnRm9hRkdBdFJyT1BVcGR5UG1lbkxy?=
 =?utf-8?B?dktzaHV6MksyTmQydzRCb1FHTnUyUnlmZys4Z01XR3VTeW1JNHQ1RWFtM29Z?=
 =?utf-8?B?cm5heWFuWUxsUHdtaFo5MHFQTXlUcjhwMHpwL0p1SlRoSFRCM2t0dG1vanRs?=
 =?utf-8?B?Q0pmZjVtdS8zVHBCamxVOUhzdGlnNXR3Q3ZpYWFpYkZJaCsvaWVlbWdWYkQy?=
 =?utf-8?B?UUdpa3ErSWlwdjAwY2ZabUQxS2p1Q0ZjcGxGTDRCcE5GOW4yY1pQS3NYNnNW?=
 =?utf-8?B?UXRSSDlIVksyUnhqTlIxVDc0aEp4YXUxcURnV0psRkYzMnNsMmszMG9HV1hV?=
 =?utf-8?B?RExuMU9xQmdLQ1paZUQ3Tyt3Y0pXVEdoVnRuemFCYmFCVXBrUHhyOE9GdTJt?=
 =?utf-8?B?WnRta1JEcWxlMEFpelJTYnNLMlVJUElOaEZ5MnNqK3NQTzhORjRadlhiOXhl?=
 =?utf-8?B?VmhFMHZYMTZuYnFqZGNVRDBySkI2bERRbGV3cnNHZ29HTm5MVCtXdFBZQmFu?=
 =?utf-8?B?d05QVnFVd2F3TDh4SEsyK2lSWVI5bHJYd0dvREtnV0dmelh1RFNhcVZWWFZC?=
 =?utf-8?B?cnBwdHEwcEl6bTFCOVY4RW95cWc1M1VDdFIwdmplbnA0ZDljc2d6bTZQSE5L?=
 =?utf-8?B?Q0lKOVhxeWNwbGVORGFrZ3RGNlBMVWxOeVJXM29sakplZlFkVTcvYy9oQWNN?=
 =?utf-8?B?ZzhFYitOWkRIZVo4aWptUWNWY0F5dEtqWTI5SkVoRzRyRmNZZjFFZjk2VG9G?=
 =?utf-8?B?UEtVcmJSNGJSc2VXQlNBUWFYWFRXRVBFakpJVUNHQk0rU3graGx6bFIwYnBr?=
 =?utf-8?B?TGVSYmk3NldxWFQ2NGkyZysxd01QUUpJUVB3MzdlalljMlluYjhlQlhGN1R0?=
 =?utf-8?B?dXdvczhUOWlMb1JmL0NGK1NSUEhiWGFia0NPTHlZVVNkdFRiL0NJbGwrV3Y5?=
 =?utf-8?B?M2h1SWhpa1pZZGtOcGU3QWV5QWxSamlRR0lpcEZzMU4vYUZzcWRtRytoMGhV?=
 =?utf-8?B?bjNMTXBVVnI5S1RmaHgzcSs3QW9GaDliWFBoeUQ3U0dVTE9BMGxNY2hFOFdQ?=
 =?utf-8?B?RGJwclNBQVhSSlg0Vi81TUZ1NEwxSThHU1pValk2RnVMbUsxZEw2bFQvVTRk?=
 =?utf-8?Q?u1j+2hwCp46rKu/IcbQa2dXCfG+/oPZl9unLUmkSzpyK?=
X-OriginatorOrg: amd.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 67b7ec6f-b4af-4832-23c0-08da85da577d
X-MS-Exchange-CrossTenant-AuthSource: BN8PR12MB3587.namprd12.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 24 Aug 2022 14:11:15.3638
 (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: MTY5k8ED+mNcVUDjvJ5HsDVekfcgtBKL3p44ies0fA2tsJvqTNu1kTc77Ran8cDH
X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR12MB2921
X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED,
        DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,NICE_REPLY_A,RCVD_IN_DNSWL_NONE,
        RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,SPF_PASS,T_SCC_BODY_TEXT_LINE,
        URIBL_BLOCKED autolearn=ham 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 24.08.22 um 12:22 schrieb Dmitry Osipenko:
> The internal dma-buf lock isn't needed anymore because the updated
> locking specification claims that dma-buf reservation must be locked
> by importers, and thus, the internal data is already protected by the
> reservation lock. Remove the obsoleted internal lock.
>
> Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>

Reviewed-by: Christian König <christian.koenig@amd.com>

> ---
>   drivers/dma-buf/dma-buf.c | 14 ++++----------
>   include/linux/dma-buf.h   |  9 ---------
>   2 files changed, 4 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> index 696d132b02f4..a0406254f0ae 100644
> --- a/drivers/dma-buf/dma-buf.c
> +++ b/drivers/dma-buf/dma-buf.c
> @@ -656,7 +656,6 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
>   
>   	dmabuf->file = file;
>   
> -	mutex_init(&dmabuf->lock);
>   	INIT_LIST_HEAD(&dmabuf->attachments);
>   
>   	mutex_lock(&db_list.lock);
> @@ -1503,7 +1502,7 @@ EXPORT_SYMBOL_NS_GPL(dma_buf_mmap_unlocked, DMA_BUF);
>   int dma_buf_vmap(struct dma_buf *dmabuf, struct iosys_map *map)
>   {
>   	struct iosys_map ptr;
> -	int ret = 0;
> +	int ret;
>   
>   	iosys_map_clear(map);
>   
> @@ -1515,28 +1514,25 @@ int dma_buf_vmap(struct dma_buf *dmabuf, struct iosys_map *map)
>   	if (!dmabuf->ops->vmap)
>   		return -EINVAL;
>   
> -	mutex_lock(&dmabuf->lock);
>   	if (dmabuf->vmapping_counter) {
>   		dmabuf->vmapping_counter++;
>   		BUG_ON(iosys_map_is_null(&dmabuf->vmap_ptr));
>   		*map = dmabuf->vmap_ptr;
> -		goto out_unlock;
> +		return 0;
>   	}
>   
>   	BUG_ON(iosys_map_is_set(&dmabuf->vmap_ptr));
>   
>   	ret = dmabuf->ops->vmap(dmabuf, &ptr);
>   	if (WARN_ON_ONCE(ret))
> -		goto out_unlock;
> +		return ret;
>   
>   	dmabuf->vmap_ptr = ptr;
>   	dmabuf->vmapping_counter = 1;
>   
>   	*map = dmabuf->vmap_ptr;
>   
> -out_unlock:
> -	mutex_unlock(&dmabuf->lock);
> -	return ret;
> +	return 0;
>   }
>   EXPORT_SYMBOL_NS_GPL(dma_buf_vmap, DMA_BUF);
>   
> @@ -1578,13 +1574,11 @@ void dma_buf_vunmap(struct dma_buf *dmabuf, struct iosys_map *map)
>   	BUG_ON(dmabuf->vmapping_counter == 0);
>   	BUG_ON(!iosys_map_is_equal(&dmabuf->vmap_ptr, map));
>   
> -	mutex_lock(&dmabuf->lock);
>   	if (--dmabuf->vmapping_counter == 0) {
>   		if (dmabuf->ops->vunmap)
>   			dmabuf->ops->vunmap(dmabuf, map);
>   		iosys_map_clear(&dmabuf->vmap_ptr);
>   	}
> -	mutex_unlock(&dmabuf->lock);
>   }
>   EXPORT_SYMBOL_NS_GPL(dma_buf_vunmap, DMA_BUF);
>   
> diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
> index d48d534dc55c..aed6695bbb50 100644
> --- a/include/linux/dma-buf.h
> +++ b/include/linux/dma-buf.h
> @@ -326,15 +326,6 @@ struct dma_buf {
>   	/** @ops: dma_buf_ops associated with this buffer object. */
>   	const struct dma_buf_ops *ops;
>   
> -	/**
> -	 * @lock:
> -	 *
> -	 * Used internally to serialize list manipulation, attach/detach and
> -	 * vmap/unmap. Note that in many cases this is superseeded by
> -	 * dma_resv_lock() on @resv.
> -	 */
> -	struct mutex lock;
> -
>   	/**
>   	 * @vmapping_counter:
>   	 *