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 99FE9C432BE for ; Wed, 25 Aug 2021 10:27:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8162B610C7 for ; Wed, 25 Aug 2021 10:27:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240323AbhHYK20 (ORCPT ); Wed, 25 Aug 2021 06:28:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41114 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240346AbhHYK2I (ORCPT ); Wed, 25 Aug 2021 06:28:08 -0400 Received: from mail-pf1-x433.google.com (mail-pf1-x433.google.com [IPv6:2607:f8b0:4864:20::433]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 33048C06129F; Wed, 25 Aug 2021 03:27:07 -0700 (PDT) Received: by mail-pf1-x433.google.com with SMTP id r9so4787950pfh.6; Wed, 25 Aug 2021 03:27:07 -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=ZiZptxAG6LZlwjR95iOzUI6M5xQ+c4I+M1PZ5LikpHE=; b=hBK8jLnz+Qvhn9vJow4RjUvNtdb4EOIVfTN9Df0pqvZGRzhpFOHLBNw4tmkYhbXP0O i3vrPrX8jjED7W2mAwTWfMFP5b7/t2FRtMrR0FJSt/U864PEVKnvw/mdUciFtytnvkm2 1l5QOWUEHAkfaK5MP7d9rEzDG7b4YQiT4Z5Cvh2ZeCvnFXVF1B6kGaeXbj01mPn4oFtn gCHjyg6d0MeG30CGzA/ue2z4P+bVseZblBqnXX57g2D7sc4DuEahkPuGRf9MgePRzusT lo55pmUHaBLL0JHGbN9FHNSYfBZu7+fWjP0aiJ0i3PCkjFF7P/w2CHrn5k/U/+cLQ1fi L3lA== 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=ZiZptxAG6LZlwjR95iOzUI6M5xQ+c4I+M1PZ5LikpHE=; b=H9s/h4RN+OacoLcO1N7maQJX2XrcDMkuQvpVVMAhgmsXomGw8RB1AR4StiYKejVk5U ZBCVggfWterCQedx2CvKbyW/+Tyoy2TPpzpDZ7nBD59lCP8jRnX7QTVauZp1oEs1GPoC e7PbE8uV4SY/OXDaaG3i+XOpafKSTVY4OS5S+hgLYxxZs1/KCEig985QeckFRMZMTS3Z jjMpRO/7gW8gSCweruw1W9PbsXbsxpdTR662Ubqdvd6aW+8AWN2N++FT2w7AEqQxHA0U sSP0rAUpyCuDMr1QkrlDi5UXt5bQnqbKZmziBVL6Gfuxbdc+TLtegf0JNncPc/VnKk+M QlXQ== X-Gm-Message-State: AOAM533Ir36/4DC0Nt1ZxfF4GLEpV7F0N5Q0bdUpkro/KZMpUdx+Wtd5 8k5oK6LDN4GXovEjYOYKX4Q= X-Google-Smtp-Source: ABdhPJwpGHyw/JNX8vQV+9CxZcjmMtcAfrqRTNZJ2G1s/7vSRd37Xu0JMq88+7TSzkG9QKgoG6Pv9A== X-Received: by 2002:a05:6a00:2491:b0:3ef:5233:8f6 with SMTP id c17-20020a056a00249100b003ef523308f6mr3421378pfv.45.1629887226719; Wed, 25 Aug 2021 03:27:06 -0700 (PDT) Received: from localhost.localdomain ([118.200.190.93]) by smtp.gmail.com with ESMTPSA id t42sm10228377pfg.30.2021.08.25.03.26.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Aug 2021 03:27:06 -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, jani.nikula@linux.intel.com, joonas.lahtinen@linux.intel.com, rodrigo.vivi@intel.com, chris@chris-wilson.co.uk, ville.syrjala@linux.intel.com, matthew.auld@intel.com, dan.carpenter@oracle.com, tvrtko.ursulin@intel.com, matthew.d.roper@intel.com, lucas.demarchi@intel.com, karthik.b.s@intel.com, jose.souza@intel.com, manasi.d.navare@intel.com, airlied@redhat.com, aditya.swarup@intel.com, andrescj@chromium.org, linux-graphics-maintainer@vmware.com, zackr@vmware.com Cc: Desmond Cheong Zhi Xi , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, intel-gfx@lists.freedesktop.org, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org, skhan@linuxfoundation.org, gregkh@linuxfoundation.org, linux-kernel-mentees@lists.linuxfoundation.org Subject: [PATCH v6 7/7] drm: remove drm_file.master_lookup_lock Date: Wed, 25 Aug 2021 18:24:11 +0800 Message-Id: <20210825102411.1084220-8-desmondcheongzx@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210825102411.1084220-1-desmondcheongzx@gmail.com> References: <20210825102411.1084220-1-desmondcheongzx@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Previously, master_lookup_lock was introduced in commit 0b0860a3cf5e ("drm: serialize drm_file.master with a new spinlock") to serialize accesses to drm_file.master. This then allowed us to write drm_file_get_master in commit 56f0729a510f ("drm: protect drm_master pointers in drm_lease.c"). The rationale behind introducing a new spinlock at the time was that the other lock that could have been used (drm_device.master_mutex) was the outermost lock, so embedding calls to drm_file_get_master and drm_is_current_master in various functions easily caused us to invert the lock hierarchy. Following the conversion of master_mutex into a rwsem, and its use to plug races with modesetting rights, we've untangled some lock hierarchies and removed the need for using drm_file_get_master and the unlocked version of drm_is_current_master in multiple places. Hence, we can take this opportunity to clean up the locking design by replacing master_lookup_lock with drm_device.master_rwsem. Signed-off-by: Desmond Cheong Zhi Xi --- drivers/gpu/drm/drm_auth.c | 19 +++++++------------ drivers/gpu/drm/drm_file.c | 1 - drivers/gpu/drm/drm_internal.h | 1 + drivers/gpu/drm/drm_ioctl.c | 4 ++-- drivers/gpu/drm/drm_lease.c | 18 ++++++++---------- include/drm/drm_file.h | 9 +-------- 6 files changed, 19 insertions(+), 33 deletions(-) diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c index f2b2f197052a..232416119407 100644 --- a/drivers/gpu/drm/drm_auth.c +++ b/drivers/gpu/drm/drm_auth.c @@ -61,10 +61,9 @@ * trusted clients. */ -static bool drm_is_current_master_locked(struct drm_file *fpriv) +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_rwsem)); + lockdep_assert_held_once(&fpriv->minor->dev->master_rwsem); return fpriv->is_master && drm_lease_owner(fpriv->master) == fpriv->minor->dev->master; } @@ -83,9 +82,9 @@ bool drm_is_current_master(struct drm_file *fpriv) { bool ret; - spin_lock(&fpriv->master_lookup_lock); + down_read(&fpriv->minor->dev->master_rwsem); ret = drm_is_current_master_locked(fpriv); - spin_unlock(&fpriv->master_lookup_lock); + up_read(&fpriv->minor->dev->master_rwsem); return ret; } @@ -120,7 +119,7 @@ int drm_authmagic(struct drm_device *dev, void *data, DRM_DEBUG("%u\n", auth->magic); down_write(&dev->master_rwsem); - if (unlikely(!drm_is_current_master(file_priv))) { + if (unlikely(!drm_is_current_master_locked(file_priv))) { up_write(&dev->master_rwsem); return -EACCES; } @@ -178,9 +177,7 @@ static int drm_new_set_master(struct drm_device *dev, struct drm_file *fpriv) new_master = drm_master_create(dev); if (!new_master) return -ENOMEM; - spin_lock(&fpriv->master_lookup_lock); fpriv->master = new_master; - spin_unlock(&fpriv->master_lookup_lock); fpriv->is_master = 1; fpriv->authenticated = 1; @@ -343,9 +340,7 @@ int drm_master_open(struct drm_file *file_priv) if (!dev->master) { ret = drm_new_set_master(dev, file_priv); } else { - spin_lock(&file_priv->master_lookup_lock); file_priv->master = drm_master_get(dev->master); - spin_unlock(&file_priv->master_lookup_lock); } up_write(&dev->master_rwsem); @@ -413,13 +408,13 @@ struct drm_master *drm_file_get_master(struct drm_file *file_priv) if (!file_priv) return NULL; - spin_lock(&file_priv->master_lookup_lock); + down_read(&file_priv->minor->dev->master_rwsem); if (!file_priv->master) goto unlock; master = drm_master_get(file_priv->master); unlock: - spin_unlock(&file_priv->master_lookup_lock); + up_read(&file_priv->minor->dev->master_rwsem); return master; } EXPORT_SYMBOL(drm_file_get_master); diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c index 90b62f360da1..8c846e0179d7 100644 --- a/drivers/gpu/drm/drm_file.c +++ b/drivers/gpu/drm/drm_file.c @@ -176,7 +176,6 @@ struct drm_file *drm_file_alloc(struct drm_minor *minor) init_waitqueue_head(&file->event_wait); file->event_space = 4096; /* set aside 4k for event buffer */ - spin_lock_init(&file->master_lookup_lock); mutex_init(&file->event_read_lock); if (drm_core_check_feature(dev, DRIVER_GEM)) diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h index 17f3548c8ed2..5d421f749a17 100644 --- a/drivers/gpu/drm/drm_internal.h +++ b/drivers/gpu/drm/drm_internal.h @@ -132,6 +132,7 @@ int drm_crtc_queue_sequence_ioctl(struct drm_device *dev, void *data, struct drm_file *filp); /* drm_auth.c */ +bool drm_is_current_master_locked(struct drm_file *fpriv); int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv); int drm_authmagic(struct drm_device *dev, void *data, diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c index 8bea39ffc5c0..c728437466c3 100644 --- a/drivers/gpu/drm/drm_ioctl.c +++ b/drivers/gpu/drm/drm_ioctl.c @@ -386,7 +386,7 @@ static int drm_setversion(struct drm_device *dev, void *data, struct drm_file *f int if_version, retcode = 0; down_write(&dev->master_rwsem); - if (unlikely(!drm_is_current_master(file_priv))) { + if (unlikely(!drm_is_current_master_locked(file_priv))) { retcode = -EACCES; goto unlock; } @@ -540,7 +540,7 @@ static int drm_ioctl_permit(u32 flags, struct drm_file *file_priv) /* MASTER is only for master or control clients */ if (unlikely((flags & DRM_MASTER) && - !drm_is_current_master(file_priv))) + !drm_is_current_master_locked(file_priv))) return -EACCES; /* Render clients must be explicitly allowed */ diff --git a/drivers/gpu/drm/drm_lease.c b/drivers/gpu/drm/drm_lease.c index 15bf3a3c76d1..0eecf320b1ab 100644 --- a/drivers/gpu/drm/drm_lease.c +++ b/drivers/gpu/drm/drm_lease.c @@ -498,12 +498,12 @@ int drm_mode_create_lease_ioctl(struct drm_device *dev, return PTR_ERR(lessee_file); down_read(&dev->master_rwsem); - if (unlikely(!drm_is_current_master(lessor_priv))) { + if (unlikely(!drm_is_current_master_locked(lessor_priv))) { ret = -EACCES; goto out_file; } - lessor = drm_file_get_master(lessor_priv); + lessor = lessor_priv->master; /* Do not allow sub-leases */ if (lessor->lessor) { DRM_DEBUG_LEASE("recursive leasing not allowed\n"); @@ -565,7 +565,6 @@ int drm_mode_create_lease_ioctl(struct drm_device *dev, /* Hook up the fd */ fd_install(fd, lessee_file); - drm_master_put(&lessor); up_read(&dev->master_rwsem); DRM_DEBUG_LEASE("drm_mode_create_lease_ioctl succeeded\n"); return 0; @@ -600,7 +599,8 @@ int drm_mode_list_lessees_ioctl(struct drm_device *dev, if (!drm_core_check_feature(dev, DRIVER_MODESET)) return -EOPNOTSUPP; - lessor = drm_file_get_master(lessor_priv); + lockdep_assert_held_once(&dev->master_rwsem); + lessor = lessor_priv->master; DRM_DEBUG_LEASE("List lessees for %d\n", lessor->lessee_id); mutex_lock(&dev->mode_config.idr_mutex); @@ -624,7 +624,6 @@ int drm_mode_list_lessees_ioctl(struct drm_device *dev, arg->count_lessees = count; mutex_unlock(&dev->mode_config.idr_mutex); - drm_master_put(&lessor); return ret; } @@ -650,7 +649,8 @@ int drm_mode_get_lease_ioctl(struct drm_device *dev, if (!drm_core_check_feature(dev, DRIVER_MODESET)) return -EOPNOTSUPP; - lessee = drm_file_get_master(lessee_priv); + lockdep_assert_held_once(&dev->master_rwsem); + lessee = lessee_priv->master; DRM_DEBUG_LEASE("get lease for %d\n", lessee->lessee_id); mutex_lock(&dev->mode_config.idr_mutex); @@ -678,7 +678,6 @@ int drm_mode_get_lease_ioctl(struct drm_device *dev, arg->count_objects = count; mutex_unlock(&dev->mode_config.idr_mutex); - drm_master_put(&lessee); return ret; } @@ -703,11 +702,11 @@ int drm_mode_revoke_lease_ioctl(struct drm_device *dev, return -EOPNOTSUPP; down_write(&dev->master_rwsem); - if (unlikely(!drm_is_current_master(lessor_priv))) { + if (unlikely(!drm_is_current_master_locked(lessor_priv))) { ret = -EACCES; goto unlock; } - lessor = drm_file_get_master(lessor_priv); + lessor = lessor_priv->master; mutex_lock(&dev->mode_config.idr_mutex); lessee = _drm_find_lessee(lessor, arg->lessee_id); @@ -728,7 +727,6 @@ int drm_mode_revoke_lease_ioctl(struct drm_device *dev, fail: mutex_unlock(&dev->mode_config.idr_mutex); - drm_master_put(&lessor); unlock: up_write(&dev->master_rwsem); diff --git a/include/drm/drm_file.h b/include/drm/drm_file.h index d12bb2ba7814..e2d49fe3e32d 100644 --- a/include/drm/drm_file.h +++ b/include/drm/drm_file.h @@ -227,16 +227,12 @@ struct drm_file { * @master: * * Master this node is currently associated with. Protected by struct - * &drm_device.master_rwsem, and serialized by @master_lookup_lock. + * &drm_device.master_rwsem. * * 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_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_rwsem for the duration of the pointer's use, or * use drm_file_get_master() if struct &drm_device.master_rwsem is not @@ -248,9 +244,6 @@ struct drm_file { */ struct drm_master *master; - /** @master_lock: Serializes @master. */ - spinlock_t master_lookup_lock; - /** @pid: Process that opened this file. */ struct pid *pid; -- 2.25.1