From patchwork Tue Jun 22 07:54:09 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Vetter X-Patchwork-Id: 12336539 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=-16.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 7816DC2B9F4 for ; Tue, 22 Jun 2021 07:54:22 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (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 CE6A9611CE for ; Tue, 22 Jun 2021 07:54:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CE6A9611CE Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ffwll.ch Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 2D5C56E408; Tue, 22 Jun 2021 07:54:20 +0000 (UTC) Received: from mail-wr1-x42d.google.com (mail-wr1-x42d.google.com [IPv6:2a00:1450:4864:20::42d]) by gabe.freedesktop.org (Postfix) with ESMTPS id 612FD6E3F7 for ; Tue, 22 Jun 2021 07:54:17 +0000 (UTC) Received: by mail-wr1-x42d.google.com with SMTP id m18so22473352wrv.2 for ; Tue, 22 Jun 2021 00:54:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=LhH8oe/P3I1pzGmmehyVUQA+j57rQxFhoVV75MXvrbE=; b=iMYkmuMmAuc7zCSmFtjhahXRlmloWJjVkF/yHNExxDjbBJPt3xiwKtj9qr9Iqq3cBd GKjNg+bmnWoDpyJhSL8AklbZkYxHv7pu4AiebKBhnlyKv5Zm4UfmKUp7mRy9ZwwDSPQH 9Z+cl/OM7FFHdXLOMqHJbuaz4ApyMUDbFSGWk= 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:mime-version :content-transfer-encoding; bh=LhH8oe/P3I1pzGmmehyVUQA+j57rQxFhoVV75MXvrbE=; b=qchjh+7JE3CHrF2W+kFJLQ0Vkss13z07j1knBXObIZ6Gqi8UUnYnYXkIqLj6j1Onoa ctUSCglboz0RxMaQFaz6eNVOCt4McVUMR2BQyH64wUuH/l2Fk3qn8pna/EVfe139ZBxS 8nuqhsEJ+wH7Oko/y00Ieihx+Sxy6U+DHQh1rfgo/X0yN37Lj76/oGNzjC8myAvWly8Y YN6xszIkM2yt6qxXGjU2rFRW3DrEhgSMda73JMGAAQxxhbi9LmZmm65wtRa9/UHrd9DS 9VocyaLlPrl+FDxOzNCTj+h5vnKoY/KF7Ncl58i7Mws7fioCam5flTqvU2D9vn9KDpA7 Bncg== X-Gm-Message-State: AOAM531SCwhIuiPbUViW6X86EIliBDZEMmcHYwdPEqvWYmNk+99dMuxX Hh5NVwSKxBYAm+We8dBTVvPO+Q== X-Google-Smtp-Source: ABdhPJxQCH5xUKVEpxaBsZxWEb9pvwGN+FqzCFhxrWDsS+CTUL0E7qjy4lEy4pSUTFUm+EvaPXXXmA== X-Received: by 2002:adf:e2cf:: with SMTP id d15mr3084891wrj.48.1624348455854; Tue, 22 Jun 2021 00:54:15 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id v16sm20949920wrr.6.2021.06.22.00.54.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 22 Jun 2021 00:54:15 -0700 (PDT) From: Daniel Vetter To: Intel Graphics Development Subject: [PATCH] Revert "drm: add a locked version of drm_is_current_master" Date: Tue, 22 Jun 2021 09:54:09 +0200 Message-Id: <20210622075409.2673805-1-daniel.vetter@ffwll.ch> X-Mailer: git-send-email 2.32.0.rc2 MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Daniel Vetter , Emil Velikov , stable@vger.kernel.org, David Airlie , DRI Development , Thomas Zimmermann , Daniel Vetter , Desmond Cheong Zhi Xi Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" This reverts commit 1815d9c86e3090477fbde066ff314a7e9721ee0f. Unfortunately this inverts the locking hierarchy, so back to the drawing board. Full lockdep splat below: ====================================================== WARNING: possible circular locking dependency detected 5.13.0-rc7-CI-CI_DRM_10254+ #1 Not tainted ------------------------------------------------------ kms_frontbuffer/1087 is trying to acquire lock: ffff88810dcd01a8 (&dev->master_mutex){+.+.}-{3:3}, at: drm_is_current_master+0x1b/0x40 but task is already holding lock: ffff88810dcd0488 (&dev->mode_config.mutex){+.+.}-{3:3}, at: drm_mode_getconnector+0x1c6/0x4a0 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&dev->mode_config.mutex){+.+.}-{3:3}: __mutex_lock+0xab/0x970 drm_client_modeset_probe+0x22e/0xca0 __drm_fb_helper_initial_config_and_unlock+0x42/0x540 intel_fbdev_initial_config+0xf/0x20 [i915] async_run_entry_fn+0x28/0x130 process_one_work+0x26d/0x5c0 worker_thread+0x37/0x380 kthread+0x144/0x170 ret_from_fork+0x1f/0x30 -> #1 (&client->modeset_mutex){+.+.}-{3:3}: __mutex_lock+0xab/0x970 drm_client_modeset_commit_locked+0x1c/0x180 drm_client_modeset_commit+0x1c/0x40 __drm_fb_helper_restore_fbdev_mode_unlocked+0x88/0xb0 drm_fb_helper_set_par+0x34/0x40 intel_fbdev_set_par+0x11/0x40 [i915] fbcon_init+0x270/0x4f0 visual_init+0xc6/0x130 do_bind_con_driver+0x1e5/0x2d0 do_take_over_console+0x10e/0x180 do_fbcon_takeover+0x53/0xb0 register_framebuffer+0x22d/0x310 __drm_fb_helper_initial_config_and_unlock+0x36c/0x540 intel_fbdev_initial_config+0xf/0x20 [i915] async_run_entry_fn+0x28/0x130 process_one_work+0x26d/0x5c0 worker_thread+0x37/0x380 kthread+0x144/0x170 ret_from_fork+0x1f/0x30 -> #0 (&dev->master_mutex){+.+.}-{3:3}: __lock_acquire+0x151e/0x2590 lock_acquire+0xd1/0x3d0 __mutex_lock+0xab/0x970 drm_is_current_master+0x1b/0x40 drm_mode_getconnector+0x37e/0x4a0 drm_ioctl_kernel+0xa8/0xf0 drm_ioctl+0x1e8/0x390 __x64_sys_ioctl+0x6a/0xa0 do_syscall_64+0x39/0xb0 entry_SYSCALL_64_after_hwframe+0x44/0xae other info that might help us debug this: Chain exists of: &dev->master_mutex --> &client->modeset_mutex --> &dev->mode_config.mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&dev->mode_config.mutex); lock(&client->modeset_mutex); lock(&dev->mode_config.mutex); lock(&dev->master_mutex); *** DEADLOCK *** 1 lock held by kms_frontbuffer/1087: #0: ffff88810dcd0488 (&dev->mode_config.mutex){+.+.}-{3:3}, at: drm_mode_getconnector+0x1c6/0x4a0 stack backtrace: CPU: 7 PID: 1087 Comm: kms_frontbuffer Not tainted 5.13.0-rc7-CI-CI_DRM_10254+ #1 Hardware name: Intel Corporation Ice Lake Client Platform/IceLake U DDR4 SODIMM PD RVP TLC, BIOS ICLSFWR1.R00.3234.A01.1906141750 06/14/2019 Call Trace: dump_stack+0x7f/0xad check_noncircular+0x12e/0x150 __lock_acquire+0x151e/0x2590 lock_acquire+0xd1/0x3d0 __mutex_lock+0xab/0x970 drm_is_current_master+0x1b/0x40 drm_mode_getconnector+0x37e/0x4a0 drm_ioctl_kernel+0xa8/0xf0 drm_ioctl+0x1e8/0x390 __x64_sys_ioctl+0x6a/0xa0 do_syscall_64+0x39/0xb0 entry_SYSCALL_64_after_hwframe+0x44/0xae daniel@phenom:~/linux/drm-misc-fixes$ dim fixes 1815d9c86e3090477fbde066ff314a7e9721ee0f Fixes: 1815d9c86e30 ("drm: add a locked version of drm_is_current_master") Cc: Desmond Cheong Zhi Xi Cc: Emil Velikov Cc: stable@vger.kernel.org Signed-off-by: Daniel Vetter Cc: Maarten Lankhorst Cc: Maxime Ripard Cc: Thomas Zimmermann Cc: David Airlie Cc: Daniel Vetter Acked-by: Petri Latvala --- drivers/gpu/drm/drm_auth.c | 51 ++++++++++++++------------------------ 1 file changed, 19 insertions(+), 32 deletions(-) diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c index 86d4b72e95cb..232abbba3686 100644 --- a/drivers/gpu/drm/drm_auth.c +++ b/drivers/gpu/drm/drm_auth.c @@ -61,35 +61,6 @@ * trusted clients. */ -static bool drm_is_current_master_locked(struct drm_file *fpriv) -{ - lockdep_assert_held_once(&fpriv->master->dev->master_mutex); - - return fpriv->is_master && drm_lease_owner(fpriv->master) == fpriv->minor->dev->master; -} - -/** - * drm_is_current_master - checks whether @priv is the current master - * @fpriv: DRM file private - * - * Checks whether @fpriv is current master on its device. This decides whether a - * client is allowed to run DRM_MASTER IOCTLs. - * - * Most of the modern IOCTL which require DRM_MASTER are for kernel modesetting - * - the current master is assumed to own the non-shareable display hardware. - */ -bool drm_is_current_master(struct drm_file *fpriv) -{ - bool ret; - - mutex_lock(&fpriv->master->dev->master_mutex); - ret = drm_is_current_master_locked(fpriv); - mutex_unlock(&fpriv->master->dev->master_mutex); - - return ret; -} -EXPORT_SYMBOL(drm_is_current_master); - int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv) { struct drm_auth *auth = data; @@ -252,7 +223,7 @@ int drm_setmaster_ioctl(struct drm_device *dev, void *data, if (ret) goto out_unlock; - if (drm_is_current_master_locked(file_priv)) + if (drm_is_current_master(file_priv)) goto out_unlock; if (dev->master) { @@ -301,7 +272,7 @@ int drm_dropmaster_ioctl(struct drm_device *dev, void *data, if (ret) goto out_unlock; - if (!drm_is_current_master_locked(file_priv)) { + if (!drm_is_current_master(file_priv)) { ret = -EINVAL; goto out_unlock; } @@ -350,7 +321,7 @@ void drm_master_release(struct drm_file *file_priv) if (file_priv->magic) idr_remove(&file_priv->master->magic_map, file_priv->magic); - if (!drm_is_current_master_locked(file_priv)) + if (!drm_is_current_master(file_priv)) goto out; drm_legacy_lock_master_cleanup(dev, master); @@ -371,6 +342,22 @@ void drm_master_release(struct drm_file *file_priv) mutex_unlock(&dev->master_mutex); } +/** + * drm_is_current_master - checks whether @priv is the current master + * @fpriv: DRM file private + * + * Checks whether @fpriv is current master on its device. This decides whether a + * client is allowed to run DRM_MASTER IOCTLs. + * + * Most of the modern IOCTL which require DRM_MASTER are for kernel modesetting + * - the current master is assumed to own the non-shareable display hardware. + */ +bool drm_is_current_master(struct drm_file *fpriv) +{ + return fpriv->is_master && drm_lease_owner(fpriv->master) == fpriv->minor->dev->master; +} +EXPORT_SYMBOL(drm_is_current_master); + /** * drm_master_get - reference a master pointer * @master: &struct drm_master