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 X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8BD76C43214 for ; Tue, 31 Aug 2021 06:14:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7851E60F4B for ; Tue, 31 Aug 2021 06:14:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231717AbhHaGPu (ORCPT ); Tue, 31 Aug 2021 02:15:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38110 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230519AbhHaGPt (ORCPT ); Tue, 31 Aug 2021 02:15:49 -0400 Received: from mail-pg1-x52e.google.com (mail-pg1-x52e.google.com [IPv6:2607:f8b0:4864:20::52e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A80BBC061575; Mon, 30 Aug 2021 23:14:54 -0700 (PDT) Received: by mail-pg1-x52e.google.com with SMTP id w7so14523836pgk.13; Mon, 30 Aug 2021 23:14:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=ksT6Kc+4cXcjdZlMaFAb0YKt3gVH5WYALt2dKHx5mko=; b=uspS9QeeQgfwkZvwtL/f+vUiAlHsC0yZUEzWWNaidiAtqCIPGNFMtjHwgzuogMBJfs AJf8T1AGQSOCNWKqVBZ2jMsZJlbybVJbxNBJFzmCUYd40Sb7ftAiHuB8vhgKN3wFgRR9 n0HSf+6+lKuLOqo7bM9ED6Oh5wpsoWZOF27wHO7OYVprvsIWwb/On0Mt2SmZgdE+MzjM sVJ1X0oUOsViPuKtr0+MGJb9US7oLh5tdtNo9W+I6g9Ugnqlt8FQYb378+R1mGSkrSUj jhY7JROv0/BV1laea79WyjnocMJCzDxDSVnvbIsvgqHvPMJLQEAxqsuNKfIWhgk19KFk KngQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=ksT6Kc+4cXcjdZlMaFAb0YKt3gVH5WYALt2dKHx5mko=; b=nEe8Xk56H7PTJWqGZMwvRx9bmVRKV2RtE0SqXycaSYb8CJXX3zAgH2eEMFk1mmHxUB BI3pai7AsRh09gmdUyKSJaPV9u9sTKpOjvNDTsUJYACJFWb3OK5wpAg8Gi02WKBAf1IO Ovf6rW+nEzgWru33lEAZRNXxFrgqQmtVZupGGKsoEO5L6UIUNLVjdF8xuDiy7UV3ceTN cOsnxuTTvKor7iTIKjVrPGzdZakhbV5W9Iqgwp9j/WMgTvejMJCiXN6XT+iOUwWQhBgV isGI6SdOjrlucl8e+T1uhIGwsKuhYz8Iz3Z8SqXQUmv9XhaXLdAsZ4T5KteE4s3VVKf1 IMrg== X-Gm-Message-State: AOAM531xBFVoalLcIrKSGPne7qoLRv3aHjNtc0nENXxniZFNXPEV+Ld1 uIb74FplEnAi1aO3O7WY6X8= X-Google-Smtp-Source: ABdhPJx2eLZnttCUyxAf64iMhS7su0aL0z4KWBYqMGIy0eiCAtx2S7QlOJ9204/CcMjeKqj30iQGlA== X-Received: by 2002:aa7:8d0c:0:b029:3e0:2e32:3148 with SMTP id j12-20020aa78d0c0000b02903e02e323148mr26954205pfe.23.1630390494148; Mon, 30 Aug 2021 23:14:54 -0700 (PDT) Received: from sanitydock.wifi-cloud.jp ([210.160.217.69]) by smtp.gmail.com with ESMTPSA id z7sm1405724pjr.42.2021.08.30.23.14.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 Aug 2021 23:14:53 -0700 (PDT) From: Desmond Cheong Zhi Xi To: maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de, airlied@linux.ie, daniel@ffwll.ch, sumit.semwal@linaro.org, christian.koenig@amd.com Cc: Desmond Cheong Zhi Xi , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, intel-gfx@lists.freedesktop.org, skhan@linuxfoundation.org, gregkh@linuxfoundation.org, linux-kernel-mentees@lists.linuxfoundation.org, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org, Daniel Vetter Subject: [PATCH v9 2/4] drm: convert drm_device.master_mutex into a rwsem Date: Tue, 31 Aug 2021 14:13:46 +0800 Message-Id: <20210831061348.97696-3-desmondcheongzx@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210831061348.97696-1-desmondcheongzx@gmail.com> References: <20210831061348.97696-1-desmondcheongzx@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org drm_device.master_mutex currently protects the following: - drm_device.master - drm_file.master - drm_file.was_master - drm_file.is_master - drm_master.unique - drm_master.unique_len - drm_master.magic_map There is a clear separation between functions that read or change these attributes. Hence, convert master_mutex into a rwsem to enable concurrent readers. Signed-off-by: Desmond Cheong Zhi Xi Reviewed-by: Daniel Vetter --- drivers/gpu/drm/drm_auth.c | 35 ++++++++++++++++++----------------- drivers/gpu/drm/drm_debugfs.c | 4 ++-- drivers/gpu/drm/drm_drv.c | 3 +-- drivers/gpu/drm/drm_ioctl.c | 10 +++++----- include/drm/drm_auth.h | 6 +++--- include/drm/drm_device.h | 10 ++++++---- include/drm/drm_file.h | 12 ++++++------ 7 files changed, 41 insertions(+), 39 deletions(-) diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c index 60a6b21474b1..73ade0513ccb 100644 --- a/drivers/gpu/drm/drm_auth.c +++ b/drivers/gpu/drm/drm_auth.c @@ -64,7 +64,7 @@ static bool drm_is_current_master_locked(struct drm_file *fpriv) { lockdep_assert_once(lockdep_is_held(&fpriv->master_lookup_lock) || - lockdep_is_held(&fpriv->minor->dev->master_mutex)); + lockdep_is_held(&fpriv->minor->dev->master_rwsem)); return fpriv->is_master && drm_lease_owner(fpriv->master) == fpriv->minor->dev->master; } @@ -96,7 +96,7 @@ int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv) struct drm_auth *auth = data; int ret = 0; - mutex_lock(&dev->master_mutex); + down_write(&dev->master_rwsem); if (!file_priv->magic) { ret = idr_alloc(&file_priv->master->magic_map, file_priv, 1, 0, GFP_KERNEL); @@ -104,7 +104,7 @@ int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv) file_priv->magic = ret; } auth->magic = file_priv->magic; - mutex_unlock(&dev->master_mutex); + up_write(&dev->master_rwsem); DRM_DEBUG("%u\n", auth->magic); @@ -119,13 +119,13 @@ int drm_authmagic(struct drm_device *dev, void *data, DRM_DEBUG("%u\n", auth->magic); - mutex_lock(&dev->master_mutex); + down_write(&dev->master_rwsem); file = idr_find(&file_priv->master->magic_map, auth->magic); if (file) { file->authenticated = 1; idr_replace(&file_priv->master->magic_map, NULL, auth->magic); } - mutex_unlock(&dev->master_mutex); + up_write(&dev->master_rwsem); return file ? 0 : -EINVAL; } @@ -167,7 +167,7 @@ static int drm_new_set_master(struct drm_device *dev, struct drm_file *fpriv) struct drm_master *old_master; struct drm_master *new_master; - lockdep_assert_held_once(&dev->master_mutex); + lockdep_assert_held_once(&dev->master_rwsem); WARN_ON(fpriv->is_master); old_master = fpriv->master; @@ -249,7 +249,7 @@ int drm_setmaster_ioctl(struct drm_device *dev, void *data, { int ret; - mutex_lock(&dev->master_mutex); + down_write(&dev->master_rwsem); ret = drm_master_check_perm(dev, file_priv); if (ret) @@ -281,7 +281,7 @@ int drm_setmaster_ioctl(struct drm_device *dev, void *data, drm_set_master(dev, file_priv, false); out_unlock: - mutex_unlock(&dev->master_mutex); + up_write(&dev->master_rwsem); return ret; } @@ -298,7 +298,7 @@ int drm_dropmaster_ioctl(struct drm_device *dev, void *data, { int ret; - mutex_lock(&dev->master_mutex); + down_write(&dev->master_rwsem); ret = drm_master_check_perm(dev, file_priv); if (ret) @@ -321,8 +321,9 @@ int drm_dropmaster_ioctl(struct drm_device *dev, void *data, } drm_drop_master(dev, file_priv); + out_unlock: - mutex_unlock(&dev->master_mutex); + up_write(&dev->master_rwsem); return ret; } @@ -334,7 +335,7 @@ int drm_master_open(struct drm_file *file_priv) /* if there is no current master make this fd it, but do not create * any master object for render clients */ - mutex_lock(&dev->master_mutex); + down_write(&dev->master_rwsem); if (!dev->master) { ret = drm_new_set_master(dev, file_priv); } else { @@ -342,7 +343,7 @@ int drm_master_open(struct drm_file *file_priv) file_priv->master = drm_master_get(dev->master); spin_unlock(&file_priv->master_lookup_lock); } - mutex_unlock(&dev->master_mutex); + up_write(&dev->master_rwsem); return ret; } @@ -352,7 +353,7 @@ void drm_master_release(struct drm_file *file_priv) struct drm_device *dev = file_priv->minor->dev; struct drm_master *master; - mutex_lock(&dev->master_mutex); + down_write(&dev->master_rwsem); master = file_priv->master; if (file_priv->magic) idr_remove(&file_priv->master->magic_map, file_priv->magic); @@ -375,7 +376,7 @@ void drm_master_release(struct drm_file *file_priv) /* drop the master reference held by the file priv */ if (file_priv->master) drm_master_put(&file_priv->master); - mutex_unlock(&dev->master_mutex); + up_write(&dev->master_rwsem); } /** @@ -450,9 +451,9 @@ EXPORT_SYMBOL(drm_master_put); /* Used by drm_client and drm_fb_helper */ bool drm_master_internal_acquire(struct drm_device *dev) { - mutex_lock(&dev->master_mutex); + down_read(&dev->master_rwsem); if (dev->master) { - mutex_unlock(&dev->master_mutex); + up_read(&dev->master_rwsem); return false; } @@ -463,6 +464,6 @@ EXPORT_SYMBOL(drm_master_internal_acquire); /* Used by drm_client and drm_fb_helper */ void drm_master_internal_release(struct drm_device *dev) { - mutex_unlock(&dev->master_mutex); + up_read(&dev->master_rwsem); } EXPORT_SYMBOL(drm_master_internal_release); diff --git a/drivers/gpu/drm/drm_debugfs.c b/drivers/gpu/drm/drm_debugfs.c index b0a826489488..b34c9c263188 100644 --- a/drivers/gpu/drm/drm_debugfs.c +++ b/drivers/gpu/drm/drm_debugfs.c @@ -55,7 +55,7 @@ static int drm_name_info(struct seq_file *m, void *data) struct drm_device *dev = minor->dev; struct drm_master *master; - mutex_lock(&dev->master_mutex); + down_read(&dev->master_rwsem); master = dev->master; seq_printf(m, "%s", dev->driver->name); if (dev->dev) @@ -65,7 +65,7 @@ static int drm_name_info(struct seq_file *m, void *data) if (dev->unique) seq_printf(m, " unique=%s", dev->unique); seq_printf(m, "\n"); - mutex_unlock(&dev->master_mutex); + up_read(&dev->master_rwsem); return 0; } diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c index 7a5097467ba5..4556bf42954c 100644 --- a/drivers/gpu/drm/drm_drv.c +++ b/drivers/gpu/drm/drm_drv.c @@ -570,7 +570,6 @@ static void drm_dev_init_release(struct drm_device *dev, void *res) /* Prevent use-after-free in drm_managed_release when debugging is * enabled. Slightly awkward, but can't really be helped. */ dev->dev = NULL; - mutex_destroy(&dev->master_mutex); mutex_destroy(&dev->clientlist_mutex); mutex_destroy(&dev->filelist_mutex); mutex_destroy(&dev->struct_mutex); @@ -611,7 +610,7 @@ static int drm_dev_init(struct drm_device *dev, mutex_init(&dev->struct_mutex); mutex_init(&dev->filelist_mutex); mutex_init(&dev->clientlist_mutex); - mutex_init(&dev->master_mutex); + init_rwsem(&dev->master_rwsem); ret = drmm_add_action(dev, drm_dev_init_release, NULL); if (ret) diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c index 26f3a9ede8fe..d25713b09b80 100644 --- a/drivers/gpu/drm/drm_ioctl.c +++ b/drivers/gpu/drm/drm_ioctl.c @@ -119,16 +119,16 @@ int drm_getunique(struct drm_device *dev, void *data, struct drm_unique *u = data; struct drm_master *master; - mutex_lock(&dev->master_mutex); + down_read(&dev->master_rwsem); master = file_priv->master; if (u->unique_len >= master->unique_len) { if (copy_to_user(u->unique, master->unique, master->unique_len)) { - mutex_unlock(&dev->master_mutex); + up_read(&dev->master_rwsem); return -EFAULT; } } u->unique_len = master->unique_len; - mutex_unlock(&dev->master_mutex); + up_read(&dev->master_rwsem); return 0; } @@ -385,7 +385,7 @@ static int drm_setversion(struct drm_device *dev, void *data, struct drm_file *f struct drm_set_version *sv = data; int if_version, retcode = 0; - mutex_lock(&dev->master_mutex); + down_write(&dev->master_rwsem); if (sv->drm_di_major != -1) { if (sv->drm_di_major != DRM_IF_MAJOR || sv->drm_di_minor < 0 || sv->drm_di_minor > DRM_IF_MINOR) { @@ -420,7 +420,7 @@ static int drm_setversion(struct drm_device *dev, void *data, struct drm_file *f sv->drm_di_minor = DRM_IF_MINOR; sv->drm_dd_major = dev->driver->major; sv->drm_dd_minor = dev->driver->minor; - mutex_unlock(&dev->master_mutex); + up_write(&dev->master_rwsem); return retcode; } diff --git a/include/drm/drm_auth.h b/include/drm/drm_auth.h index ba248ca8866f..f0a89e5fcaad 100644 --- a/include/drm/drm_auth.h +++ b/include/drm/drm_auth.h @@ -67,17 +67,17 @@ struct drm_master { struct drm_device *dev; /** * @unique: Unique identifier: e.g. busid. Protected by - * &drm_device.master_mutex. + * &drm_device.master_rwsem. */ char *unique; /** * @unique_len: Length of unique field. Protected by - * &drm_device.master_mutex. + * &drm_device.master_rwsem. */ int unique_len; /** * @magic_map: Map of used authentication tokens. Protected by - * &drm_device.master_mutex. + * &drm_device.master_rwsem. */ struct idr magic_map; void *driver_priv; diff --git a/include/drm/drm_device.h b/include/drm/drm_device.h index 604b1d1b2d72..142fb2f6e74d 100644 --- a/include/drm/drm_device.h +++ b/include/drm/drm_device.h @@ -107,7 +107,7 @@ struct drm_device { * @master: * * Currently active master for this device. - * Protected by &master_mutex + * Protected by &master_rwsem */ struct drm_master *master; @@ -146,11 +146,13 @@ struct drm_device { struct mutex struct_mutex; /** - * @master_mutex: + * @master_rwsem: * - * Lock for &drm_minor.master and &drm_file.is_master + * Lock for &drm_device.master, &drm_file.was_master, + * &drm_file.is_master, &drm_file.master, &drm_master.unique, + * &drm_master.unique_len, and &drm_master.magic_map. */ - struct mutex master_mutex; + struct rw_semaphore master_rwsem; /** * @open_count: diff --git a/include/drm/drm_file.h b/include/drm/drm_file.h index a3acb7ac3550..d12bb2ba7814 100644 --- a/include/drm/drm_file.h +++ b/include/drm/drm_file.h @@ -205,7 +205,7 @@ struct drm_file { * @was_master: * * This client has or had, master capability. Protected by struct - * &drm_device.master_mutex. + * &drm_device.master_rwsem. * * This is used to ensure that CAP_SYS_ADMIN is not enforced, if the * client is or was master in the past. @@ -216,7 +216,7 @@ struct drm_file { * @is_master: * * This client is the creator of @master. Protected by struct - * &drm_device.master_mutex. + * &drm_device.master_rwsem. * * See also the :ref:`section on primary nodes and authentication * `. @@ -227,19 +227,19 @@ struct drm_file { * @master: * * Master this node is currently associated with. Protected by struct - * &drm_device.master_mutex, and serialized by @master_lookup_lock. + * &drm_device.master_rwsem, and serialized by @master_lookup_lock. * * Only relevant if drm_is_primary_client() returns true. Note that * this only matches &drm_device.master if the master is the currently * active one. * - * To update @master, both &drm_device.master_mutex and + * To update @master, both &drm_device.master_rwsem and * @master_lookup_lock need to be held, therefore holding either of * them is safe and enough for the read side. * * When dereferencing this pointer, either hold struct - * &drm_device.master_mutex for the duration of the pointer's use, or - * use drm_file_get_master() if struct &drm_device.master_mutex is not + * &drm_device.master_rwsem for the duration of the pointer's use, or + * use drm_file_get_master() if struct &drm_device.master_rwsem is not * currently held and there is no other need to hold it. This prevents * @master from being freed during use. * -- 2.25.1 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 X-Spam-Level: X-Spam-Status: No, score=-13.5 required=3.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED,DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5BE5FC432BE for ; Tue, 31 Aug 2021 06:15:00 +0000 (UTC) Received: from smtp2.osuosl.org (smtp2.osuosl.org [140.211.166.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 1EEB060F4B for ; Tue, 31 Aug 2021 06:15:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 1EEB060F4B Authentication-Results: mail.kernel.org; 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Mon, 30 Aug 2021 23:14:53 -0700 (PDT) From: Desmond Cheong Zhi Xi To: maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de, airlied@linux.ie, daniel@ffwll.ch, sumit.semwal@linaro.org, christian.koenig@amd.com Subject: [PATCH v9 2/4] drm: convert drm_device.master_mutex into a rwsem Date: Tue, 31 Aug 2021 14:13:46 +0800 Message-Id: <20210831061348.97696-3-desmondcheongzx@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210831061348.97696-1-desmondcheongzx@gmail.com> References: <20210831061348.97696-1-desmondcheongzx@gmail.com> MIME-Version: 1.0 Cc: Daniel Vetter , intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, Desmond Cheong Zhi Xi , linux-kernel-mentees@lists.linuxfoundation.org, linux-media@vger.kernel.org X-BeenThere: linux-kernel-mentees@lists.linuxfoundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-kernel-mentees-bounces@lists.linuxfoundation.org Sender: "Linux-kernel-mentees" drm_device.master_mutex currently protects the following: - drm_device.master - drm_file.master - drm_file.was_master - drm_file.is_master - drm_master.unique - drm_master.unique_len - drm_master.magic_map There is a clear separation between functions that read or change these attributes. Hence, convert master_mutex into a rwsem to enable concurrent readers. Signed-off-by: Desmond Cheong Zhi Xi Reviewed-by: Daniel Vetter --- drivers/gpu/drm/drm_auth.c | 35 ++++++++++++++++++----------------- drivers/gpu/drm/drm_debugfs.c | 4 ++-- drivers/gpu/drm/drm_drv.c | 3 +-- drivers/gpu/drm/drm_ioctl.c | 10 +++++----- include/drm/drm_auth.h | 6 +++--- include/drm/drm_device.h | 10 ++++++---- include/drm/drm_file.h | 12 ++++++------ 7 files changed, 41 insertions(+), 39 deletions(-) diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c index 60a6b21474b1..73ade0513ccb 100644 --- a/drivers/gpu/drm/drm_auth.c +++ b/drivers/gpu/drm/drm_auth.c @@ -64,7 +64,7 @@ static bool drm_is_current_master_locked(struct drm_file *fpriv) { lockdep_assert_once(lockdep_is_held(&fpriv->master_lookup_lock) || - lockdep_is_held(&fpriv->minor->dev->master_mutex)); + lockdep_is_held(&fpriv->minor->dev->master_rwsem)); return fpriv->is_master && drm_lease_owner(fpriv->master) == fpriv->minor->dev->master; } @@ -96,7 +96,7 @@ int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv) struct drm_auth *auth = data; int ret = 0; - mutex_lock(&dev->master_mutex); + down_write(&dev->master_rwsem); if (!file_priv->magic) { ret = idr_alloc(&file_priv->master->magic_map, file_priv, 1, 0, GFP_KERNEL); @@ -104,7 +104,7 @@ int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv) file_priv->magic = ret; } auth->magic = file_priv->magic; - mutex_unlock(&dev->master_mutex); + up_write(&dev->master_rwsem); DRM_DEBUG("%u\n", auth->magic); @@ -119,13 +119,13 @@ int drm_authmagic(struct drm_device *dev, void *data, DRM_DEBUG("%u\n", auth->magic); - mutex_lock(&dev->master_mutex); + down_write(&dev->master_rwsem); file = idr_find(&file_priv->master->magic_map, auth->magic); if (file) { file->authenticated = 1; idr_replace(&file_priv->master->magic_map, NULL, auth->magic); } - mutex_unlock(&dev->master_mutex); + up_write(&dev->master_rwsem); return file ? 0 : -EINVAL; } @@ -167,7 +167,7 @@ static int drm_new_set_master(struct drm_device *dev, struct drm_file *fpriv) struct drm_master *old_master; struct drm_master *new_master; - lockdep_assert_held_once(&dev->master_mutex); + lockdep_assert_held_once(&dev->master_rwsem); WARN_ON(fpriv->is_master); old_master = fpriv->master; @@ -249,7 +249,7 @@ int drm_setmaster_ioctl(struct drm_device *dev, void *data, { int ret; - mutex_lock(&dev->master_mutex); + down_write(&dev->master_rwsem); ret = drm_master_check_perm(dev, file_priv); if (ret) @@ -281,7 +281,7 @@ int drm_setmaster_ioctl(struct drm_device *dev, void *data, drm_set_master(dev, file_priv, false); out_unlock: - mutex_unlock(&dev->master_mutex); + up_write(&dev->master_rwsem); return ret; } @@ -298,7 +298,7 @@ int drm_dropmaster_ioctl(struct drm_device *dev, void *data, { int ret; - mutex_lock(&dev->master_mutex); + down_write(&dev->master_rwsem); ret = drm_master_check_perm(dev, file_priv); if (ret) @@ -321,8 +321,9 @@ int drm_dropmaster_ioctl(struct drm_device *dev, void *data, } drm_drop_master(dev, file_priv); + out_unlock: - mutex_unlock(&dev->master_mutex); + up_write(&dev->master_rwsem); return ret; } @@ -334,7 +335,7 @@ int drm_master_open(struct drm_file *file_priv) /* if there is no current master make this fd it, but do not create * any master object for render clients */ - mutex_lock(&dev->master_mutex); + down_write(&dev->master_rwsem); if (!dev->master) { ret = drm_new_set_master(dev, file_priv); } else { @@ -342,7 +343,7 @@ int drm_master_open(struct drm_file *file_priv) file_priv->master = drm_master_get(dev->master); spin_unlock(&file_priv->master_lookup_lock); } - mutex_unlock(&dev->master_mutex); + up_write(&dev->master_rwsem); return ret; } @@ -352,7 +353,7 @@ void drm_master_release(struct drm_file *file_priv) struct drm_device *dev = file_priv->minor->dev; struct drm_master *master; - mutex_lock(&dev->master_mutex); + down_write(&dev->master_rwsem); master = file_priv->master; if (file_priv->magic) idr_remove(&file_priv->master->magic_map, file_priv->magic); @@ -375,7 +376,7 @@ void drm_master_release(struct drm_file *file_priv) /* drop the master reference held by the file priv */ if (file_priv->master) drm_master_put(&file_priv->master); - mutex_unlock(&dev->master_mutex); + up_write(&dev->master_rwsem); } /** @@ -450,9 +451,9 @@ EXPORT_SYMBOL(drm_master_put); /* Used by drm_client and drm_fb_helper */ bool drm_master_internal_acquire(struct drm_device *dev) { - mutex_lock(&dev->master_mutex); + down_read(&dev->master_rwsem); if (dev->master) { - mutex_unlock(&dev->master_mutex); + up_read(&dev->master_rwsem); return false; } @@ -463,6 +464,6 @@ EXPORT_SYMBOL(drm_master_internal_acquire); /* Used by drm_client and drm_fb_helper */ void drm_master_internal_release(struct drm_device *dev) { - mutex_unlock(&dev->master_mutex); + up_read(&dev->master_rwsem); } EXPORT_SYMBOL(drm_master_internal_release); diff --git a/drivers/gpu/drm/drm_debugfs.c b/drivers/gpu/drm/drm_debugfs.c index b0a826489488..b34c9c263188 100644 --- a/drivers/gpu/drm/drm_debugfs.c +++ b/drivers/gpu/drm/drm_debugfs.c @@ -55,7 +55,7 @@ static int drm_name_info(struct seq_file *m, void *data) struct drm_device *dev = minor->dev; struct drm_master *master; - mutex_lock(&dev->master_mutex); + down_read(&dev->master_rwsem); master = dev->master; seq_printf(m, "%s", dev->driver->name); if (dev->dev) @@ -65,7 +65,7 @@ static int drm_name_info(struct seq_file *m, void *data) if (dev->unique) seq_printf(m, " unique=%s", dev->unique); seq_printf(m, "\n"); - mutex_unlock(&dev->master_mutex); + up_read(&dev->master_rwsem); return 0; } diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c index 7a5097467ba5..4556bf42954c 100644 --- a/drivers/gpu/drm/drm_drv.c +++ b/drivers/gpu/drm/drm_drv.c @@ -570,7 +570,6 @@ static void drm_dev_init_release(struct drm_device *dev, void *res) /* Prevent use-after-free in drm_managed_release when debugging is * enabled. Slightly awkward, but can't really be helped. */ dev->dev = NULL; - mutex_destroy(&dev->master_mutex); mutex_destroy(&dev->clientlist_mutex); mutex_destroy(&dev->filelist_mutex); mutex_destroy(&dev->struct_mutex); @@ -611,7 +610,7 @@ static int drm_dev_init(struct drm_device *dev, mutex_init(&dev->struct_mutex); mutex_init(&dev->filelist_mutex); mutex_init(&dev->clientlist_mutex); - mutex_init(&dev->master_mutex); + init_rwsem(&dev->master_rwsem); ret = drmm_add_action(dev, drm_dev_init_release, NULL); if (ret) diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c index 26f3a9ede8fe..d25713b09b80 100644 --- a/drivers/gpu/drm/drm_ioctl.c +++ b/drivers/gpu/drm/drm_ioctl.c @@ -119,16 +119,16 @@ int drm_getunique(struct drm_device *dev, void *data, struct drm_unique *u = data; struct drm_master *master; - mutex_lock(&dev->master_mutex); + down_read(&dev->master_rwsem); master = file_priv->master; if (u->unique_len >= master->unique_len) { if (copy_to_user(u->unique, master->unique, master->unique_len)) { - mutex_unlock(&dev->master_mutex); + up_read(&dev->master_rwsem); return -EFAULT; } } u->unique_len = master->unique_len; - mutex_unlock(&dev->master_mutex); + up_read(&dev->master_rwsem); return 0; } @@ -385,7 +385,7 @@ static int drm_setversion(struct drm_device *dev, void *data, struct drm_file *f struct drm_set_version *sv = data; int if_version, retcode = 0; - mutex_lock(&dev->master_mutex); + down_write(&dev->master_rwsem); if (sv->drm_di_major != -1) { if (sv->drm_di_major != DRM_IF_MAJOR || sv->drm_di_minor < 0 || sv->drm_di_minor > DRM_IF_MINOR) { @@ -420,7 +420,7 @@ static int drm_setversion(struct drm_device *dev, void *data, struct drm_file *f sv->drm_di_minor = DRM_IF_MINOR; sv->drm_dd_major = dev->driver->major; sv->drm_dd_minor = dev->driver->minor; - mutex_unlock(&dev->master_mutex); + up_write(&dev->master_rwsem); return retcode; } diff --git a/include/drm/drm_auth.h b/include/drm/drm_auth.h index ba248ca8866f..f0a89e5fcaad 100644 --- a/include/drm/drm_auth.h +++ b/include/drm/drm_auth.h @@ -67,17 +67,17 @@ struct drm_master { struct drm_device *dev; /** * @unique: Unique identifier: e.g. busid. Protected by - * &drm_device.master_mutex. + * &drm_device.master_rwsem. */ char *unique; /** * @unique_len: Length of unique field. Protected by - * &drm_device.master_mutex. + * &drm_device.master_rwsem. */ int unique_len; /** * @magic_map: Map of used authentication tokens. Protected by - * &drm_device.master_mutex. + * &drm_device.master_rwsem. */ struct idr magic_map; void *driver_priv; diff --git a/include/drm/drm_device.h b/include/drm/drm_device.h index 604b1d1b2d72..142fb2f6e74d 100644 --- a/include/drm/drm_device.h +++ b/include/drm/drm_device.h @@ -107,7 +107,7 @@ struct drm_device { * @master: * * Currently active master for this device. - * Protected by &master_mutex + * Protected by &master_rwsem */ struct drm_master *master; @@ -146,11 +146,13 @@ struct drm_device { struct mutex struct_mutex; /** - * @master_mutex: + * @master_rwsem: * - * Lock for &drm_minor.master and &drm_file.is_master + * Lock for &drm_device.master, &drm_file.was_master, + * &drm_file.is_master, &drm_file.master, &drm_master.unique, + * &drm_master.unique_len, and &drm_master.magic_map. */ - struct mutex master_mutex; + struct rw_semaphore master_rwsem; /** * @open_count: diff --git a/include/drm/drm_file.h b/include/drm/drm_file.h index a3acb7ac3550..d12bb2ba7814 100644 --- a/include/drm/drm_file.h +++ b/include/drm/drm_file.h @@ -205,7 +205,7 @@ struct drm_file { * @was_master: * * This client has or had, master capability. Protected by struct - * &drm_device.master_mutex. + * &drm_device.master_rwsem. * * This is used to ensure that CAP_SYS_ADMIN is not enforced, if the * client is or was master in the past. @@ -216,7 +216,7 @@ struct drm_file { * @is_master: * * This client is the creator of @master. Protected by struct - * &drm_device.master_mutex. + * &drm_device.master_rwsem. * * See also the :ref:`section on primary nodes and authentication * `. @@ -227,19 +227,19 @@ struct drm_file { * @master: * * Master this node is currently associated with. Protected by struct - * &drm_device.master_mutex, and serialized by @master_lookup_lock. + * &drm_device.master_rwsem, and serialized by @master_lookup_lock. * * Only relevant if drm_is_primary_client() returns true. Note that * this only matches &drm_device.master if the master is the currently * active one. * - * To update @master, both &drm_device.master_mutex and + * To update @master, both &drm_device.master_rwsem and * @master_lookup_lock need to be held, therefore holding either of * them is safe and enough for the read side. * * When dereferencing this pointer, either hold struct - * &drm_device.master_mutex for the duration of the pointer's use, or - * use drm_file_get_master() if struct &drm_device.master_mutex is not + * &drm_device.master_rwsem for the duration of the pointer's use, or + * use drm_file_get_master() if struct &drm_device.master_rwsem is not * currently held and there is no other need to hold it. 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Mon, 30 Aug 2021 23:14:53 -0700 (PDT) From: Desmond Cheong Zhi Xi To: maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de, airlied@linux.ie, daniel@ffwll.ch, sumit.semwal@linaro.org, christian.koenig@amd.com Cc: Desmond Cheong Zhi Xi , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, intel-gfx@lists.freedesktop.org, skhan@linuxfoundation.org, gregkh@linuxfoundation.org, linux-kernel-mentees@lists.linuxfoundation.org, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org, Daniel Vetter Date: Tue, 31 Aug 2021 14:13:46 +0800 Message-Id: <20210831061348.97696-3-desmondcheongzx@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210831061348.97696-1-desmondcheongzx@gmail.com> References: <20210831061348.97696-1-desmondcheongzx@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Subject: [Intel-gfx] [PATCH v9 2/4] drm: convert drm_device.master_mutex into a rwsem X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" drm_device.master_mutex currently protects the following: - drm_device.master - drm_file.master - drm_file.was_master - drm_file.is_master - drm_master.unique - drm_master.unique_len - drm_master.magic_map There is a clear separation between functions that read or change these attributes. Hence, convert master_mutex into a rwsem to enable concurrent readers. Signed-off-by: Desmond Cheong Zhi Xi Reviewed-by: Daniel Vetter --- drivers/gpu/drm/drm_auth.c | 35 ++++++++++++++++++----------------- drivers/gpu/drm/drm_debugfs.c | 4 ++-- drivers/gpu/drm/drm_drv.c | 3 +-- drivers/gpu/drm/drm_ioctl.c | 10 +++++----- include/drm/drm_auth.h | 6 +++--- include/drm/drm_device.h | 10 ++++++---- include/drm/drm_file.h | 12 ++++++------ 7 files changed, 41 insertions(+), 39 deletions(-) diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c index 60a6b21474b1..73ade0513ccb 100644 --- a/drivers/gpu/drm/drm_auth.c +++ b/drivers/gpu/drm/drm_auth.c @@ -64,7 +64,7 @@ static bool drm_is_current_master_locked(struct drm_file *fpriv) { lockdep_assert_once(lockdep_is_held(&fpriv->master_lookup_lock) || - lockdep_is_held(&fpriv->minor->dev->master_mutex)); + lockdep_is_held(&fpriv->minor->dev->master_rwsem)); return fpriv->is_master && drm_lease_owner(fpriv->master) == fpriv->minor->dev->master; } @@ -96,7 +96,7 @@ int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv) struct drm_auth *auth = data; int ret = 0; - mutex_lock(&dev->master_mutex); + down_write(&dev->master_rwsem); if (!file_priv->magic) { ret = idr_alloc(&file_priv->master->magic_map, file_priv, 1, 0, GFP_KERNEL); @@ -104,7 +104,7 @@ int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv) file_priv->magic = ret; } auth->magic = file_priv->magic; - mutex_unlock(&dev->master_mutex); + up_write(&dev->master_rwsem); DRM_DEBUG("%u\n", auth->magic); @@ -119,13 +119,13 @@ int drm_authmagic(struct drm_device *dev, void *data, DRM_DEBUG("%u\n", auth->magic); - mutex_lock(&dev->master_mutex); + down_write(&dev->master_rwsem); file = idr_find(&file_priv->master->magic_map, auth->magic); if (file) { file->authenticated = 1; idr_replace(&file_priv->master->magic_map, NULL, auth->magic); } - mutex_unlock(&dev->master_mutex); + up_write(&dev->master_rwsem); return file ? 0 : -EINVAL; } @@ -167,7 +167,7 @@ static int drm_new_set_master(struct drm_device *dev, struct drm_file *fpriv) struct drm_master *old_master; struct drm_master *new_master; - lockdep_assert_held_once(&dev->master_mutex); + lockdep_assert_held_once(&dev->master_rwsem); WARN_ON(fpriv->is_master); old_master = fpriv->master; @@ -249,7 +249,7 @@ int drm_setmaster_ioctl(struct drm_device *dev, void *data, { int ret; - mutex_lock(&dev->master_mutex); + down_write(&dev->master_rwsem); ret = drm_master_check_perm(dev, file_priv); if (ret) @@ -281,7 +281,7 @@ int drm_setmaster_ioctl(struct drm_device *dev, void *data, drm_set_master(dev, file_priv, false); out_unlock: - mutex_unlock(&dev->master_mutex); + up_write(&dev->master_rwsem); return ret; } @@ -298,7 +298,7 @@ int drm_dropmaster_ioctl(struct drm_device *dev, void *data, { int ret; - mutex_lock(&dev->master_mutex); + down_write(&dev->master_rwsem); ret = drm_master_check_perm(dev, file_priv); if (ret) @@ -321,8 +321,9 @@ int drm_dropmaster_ioctl(struct drm_device *dev, void *data, } drm_drop_master(dev, file_priv); + out_unlock: - mutex_unlock(&dev->master_mutex); + up_write(&dev->master_rwsem); return ret; } @@ -334,7 +335,7 @@ int drm_master_open(struct drm_file *file_priv) /* if there is no current master make this fd it, but do not create * any master object for render clients */ - mutex_lock(&dev->master_mutex); + down_write(&dev->master_rwsem); if (!dev->master) { ret = drm_new_set_master(dev, file_priv); } else { @@ -342,7 +343,7 @@ int drm_master_open(struct drm_file *file_priv) file_priv->master = drm_master_get(dev->master); spin_unlock(&file_priv->master_lookup_lock); } - mutex_unlock(&dev->master_mutex); + up_write(&dev->master_rwsem); return ret; } @@ -352,7 +353,7 @@ void drm_master_release(struct drm_file *file_priv) struct drm_device *dev = file_priv->minor->dev; struct drm_master *master; - mutex_lock(&dev->master_mutex); + down_write(&dev->master_rwsem); master = file_priv->master; if (file_priv->magic) idr_remove(&file_priv->master->magic_map, file_priv->magic); @@ -375,7 +376,7 @@ void drm_master_release(struct drm_file *file_priv) /* drop the master reference held by the file priv */ if (file_priv->master) drm_master_put(&file_priv->master); - mutex_unlock(&dev->master_mutex); + up_write(&dev->master_rwsem); } /** @@ -450,9 +451,9 @@ EXPORT_SYMBOL(drm_master_put); /* Used by drm_client and drm_fb_helper */ bool drm_master_internal_acquire(struct drm_device *dev) { - mutex_lock(&dev->master_mutex); + down_read(&dev->master_rwsem); if (dev->master) { - mutex_unlock(&dev->master_mutex); + up_read(&dev->master_rwsem); return false; } @@ -463,6 +464,6 @@ EXPORT_SYMBOL(drm_master_internal_acquire); /* Used by drm_client and drm_fb_helper */ void drm_master_internal_release(struct drm_device *dev) { - mutex_unlock(&dev->master_mutex); + up_read(&dev->master_rwsem); } EXPORT_SYMBOL(drm_master_internal_release); diff --git a/drivers/gpu/drm/drm_debugfs.c b/drivers/gpu/drm/drm_debugfs.c index b0a826489488..b34c9c263188 100644 --- a/drivers/gpu/drm/drm_debugfs.c +++ b/drivers/gpu/drm/drm_debugfs.c @@ -55,7 +55,7 @@ static int drm_name_info(struct seq_file *m, void *data) struct drm_device *dev = minor->dev; struct drm_master *master; - mutex_lock(&dev->master_mutex); + down_read(&dev->master_rwsem); master = dev->master; seq_printf(m, "%s", dev->driver->name); if (dev->dev) @@ -65,7 +65,7 @@ static int drm_name_info(struct seq_file *m, void *data) if (dev->unique) seq_printf(m, " unique=%s", dev->unique); seq_printf(m, "\n"); - mutex_unlock(&dev->master_mutex); + up_read(&dev->master_rwsem); return 0; } diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c index 7a5097467ba5..4556bf42954c 100644 --- a/drivers/gpu/drm/drm_drv.c +++ b/drivers/gpu/drm/drm_drv.c @@ -570,7 +570,6 @@ static void drm_dev_init_release(struct drm_device *dev, void *res) /* Prevent use-after-free in drm_managed_release when debugging is * enabled. Slightly awkward, but can't really be helped. */ dev->dev = NULL; - mutex_destroy(&dev->master_mutex); mutex_destroy(&dev->clientlist_mutex); mutex_destroy(&dev->filelist_mutex); mutex_destroy(&dev->struct_mutex); @@ -611,7 +610,7 @@ static int drm_dev_init(struct drm_device *dev, mutex_init(&dev->struct_mutex); mutex_init(&dev->filelist_mutex); mutex_init(&dev->clientlist_mutex); - mutex_init(&dev->master_mutex); + init_rwsem(&dev->master_rwsem); ret = drmm_add_action(dev, drm_dev_init_release, NULL); if (ret) diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c index 26f3a9ede8fe..d25713b09b80 100644 --- a/drivers/gpu/drm/drm_ioctl.c +++ b/drivers/gpu/drm/drm_ioctl.c @@ -119,16 +119,16 @@ int drm_getunique(struct drm_device *dev, void *data, struct drm_unique *u = data; struct drm_master *master; - mutex_lock(&dev->master_mutex); + down_read(&dev->master_rwsem); master = file_priv->master; if (u->unique_len >= master->unique_len) { if (copy_to_user(u->unique, master->unique, master->unique_len)) { - mutex_unlock(&dev->master_mutex); + up_read(&dev->master_rwsem); return -EFAULT; } } u->unique_len = master->unique_len; - mutex_unlock(&dev->master_mutex); + up_read(&dev->master_rwsem); return 0; } @@ -385,7 +385,7 @@ static int drm_setversion(struct drm_device *dev, void *data, struct drm_file *f struct drm_set_version *sv = data; int if_version, retcode = 0; - mutex_lock(&dev->master_mutex); + down_write(&dev->master_rwsem); if (sv->drm_di_major != -1) { if (sv->drm_di_major != DRM_IF_MAJOR || sv->drm_di_minor < 0 || sv->drm_di_minor > DRM_IF_MINOR) { @@ -420,7 +420,7 @@ static int drm_setversion(struct drm_device *dev, void *data, struct drm_file *f sv->drm_di_minor = DRM_IF_MINOR; sv->drm_dd_major = dev->driver->major; sv->drm_dd_minor = dev->driver->minor; - mutex_unlock(&dev->master_mutex); + up_write(&dev->master_rwsem); return retcode; } diff --git a/include/drm/drm_auth.h b/include/drm/drm_auth.h index ba248ca8866f..f0a89e5fcaad 100644 --- a/include/drm/drm_auth.h +++ b/include/drm/drm_auth.h @@ -67,17 +67,17 @@ struct drm_master { struct drm_device *dev; /** * @unique: Unique identifier: e.g. busid. Protected by - * &drm_device.master_mutex. + * &drm_device.master_rwsem. */ char *unique; /** * @unique_len: Length of unique field. Protected by - * &drm_device.master_mutex. + * &drm_device.master_rwsem. */ int unique_len; /** * @magic_map: Map of used authentication tokens. Protected by - * &drm_device.master_mutex. + * &drm_device.master_rwsem. */ struct idr magic_map; void *driver_priv; diff --git a/include/drm/drm_device.h b/include/drm/drm_device.h index 604b1d1b2d72..142fb2f6e74d 100644 --- a/include/drm/drm_device.h +++ b/include/drm/drm_device.h @@ -107,7 +107,7 @@ struct drm_device { * @master: * * Currently active master for this device. - * Protected by &master_mutex + * Protected by &master_rwsem */ struct drm_master *master; @@ -146,11 +146,13 @@ struct drm_device { struct mutex struct_mutex; /** - * @master_mutex: + * @master_rwsem: * - * Lock for &drm_minor.master and &drm_file.is_master + * Lock for &drm_device.master, &drm_file.was_master, + * &drm_file.is_master, &drm_file.master, &drm_master.unique, + * &drm_master.unique_len, and &drm_master.magic_map. */ - struct mutex master_mutex; + struct rw_semaphore master_rwsem; /** * @open_count: diff --git a/include/drm/drm_file.h b/include/drm/drm_file.h index a3acb7ac3550..d12bb2ba7814 100644 --- a/include/drm/drm_file.h +++ b/include/drm/drm_file.h @@ -205,7 +205,7 @@ struct drm_file { * @was_master: * * This client has or had, master capability. Protected by struct - * &drm_device.master_mutex. + * &drm_device.master_rwsem. * * This is used to ensure that CAP_SYS_ADMIN is not enforced, if the * client is or was master in the past. @@ -216,7 +216,7 @@ struct drm_file { * @is_master: * * This client is the creator of @master. Protected by struct - * &drm_device.master_mutex. + * &drm_device.master_rwsem. * * See also the :ref:`section on primary nodes and authentication * `. @@ -227,19 +227,19 @@ struct drm_file { * @master: * * Master this node is currently associated with. Protected by struct - * &drm_device.master_mutex, and serialized by @master_lookup_lock. + * &drm_device.master_rwsem, and serialized by @master_lookup_lock. * * Only relevant if drm_is_primary_client() returns true. Note that * this only matches &drm_device.master if the master is the currently * active one. * - * To update @master, both &drm_device.master_mutex and + * To update @master, both &drm_device.master_rwsem and * @master_lookup_lock need to be held, therefore holding either of * them is safe and enough for the read side. * * When dereferencing this pointer, either hold struct - * &drm_device.master_mutex for the duration of the pointer's use, or - * use drm_file_get_master() if struct &drm_device.master_mutex is not + * &drm_device.master_rwsem for the duration of the pointer's use, or + * use drm_file_get_master() if struct &drm_device.master_rwsem is not * currently held and there is no other need to hold it. This prevents * @master from being freed during use. * -- 2.25.1