From patchwork Tue Aug 31 06:13:44 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Desmond Cheong Zhi Xi X-Patchwork-Id: 12466497 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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,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 06E35C432BE for ; Tue, 31 Aug 2021 06:14:37 +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 BF8A360F4B for ; Tue, 31 Aug 2021 06:14:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org BF8A360F4B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id DB2CA89B3C; Tue, 31 Aug 2021 06:14:33 +0000 (UTC) Received: from mail-pl1-x633.google.com (mail-pl1-x633.google.com [IPv6:2607:f8b0:4864:20::633]) by gabe.freedesktop.org (Postfix) with ESMTPS id 7872B89B22; Tue, 31 Aug 2021 06:14:32 +0000 (UTC) Received: by mail-pl1-x633.google.com with SMTP id m4so10010306pll.0; Mon, 30 Aug 2021 23:14:32 -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:mime-version :content-transfer-encoding; bh=brM7hW6JylJKzonqvDJYo3SspnbZ8CW+4pmvj8jGqAU=; b=TYqGCHFl281XM/Qsit8ay9Zvizlo3WsBq5y4Obt8jQHjiox2dt6MPHCEVsE0keSEFe RVBMplpcZxGJR3qyTkA0pPPouAWFmaRtqHYDQ5q9RW0g1lwmiQjAD0ViWNUs3dao+kx4 S2UvHOz/hjQkH9bwTm+PgxCySQVOYy02T+CcvZuSiad3G56SQJPckpPWvECGc6uGkywE 0E6AyJFNzwK/zRaE5CXVonaqmQcKxK76Jm37BWzpf5bT2UcoYiKXeREgNDRnb1NCBqZb Za6F8DrOiQ0lsDgXis4hdyTqctY0f/9POhO9D/nybaASbrGDiAI7LGYTSmzHAcUG242w s88w== 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=brM7hW6JylJKzonqvDJYo3SspnbZ8CW+4pmvj8jGqAU=; b=P86yJaFptVxKEMiHWqJvvQLQDKW3Dx2NZM2opfMeEIUDpQc/2F9ESKBZSsWKQPO736 sqL6UpZKutJtZ89U8o0Y7S+81BRBQvo4raNXU+99XV3ZNV080h56wWzJYcP6LHOw6aJE yjKJuYLiHh5JaRXmYtasShJcvfPATcjNwea/RAzVbpixeIvV2oNxjNnfbd/+XW78dFFq lte1o5hfkAefAl+NNXpzVzBODVTxk0RLAsHXS7SgQaF7G6/k2WGGEvEm08poo7sH1w8A 0uOmpSHZc5UrVhqGDbuRP4m8Bq6Z33LbUgPRXFcevn1duC7i2U79JrX9RGDHxofnkXZK mPLQ== X-Gm-Message-State: AOAM5326uSAlG5eGJ9nA4C/Dq8xclHhnt4dKtkj0rVOIjAyAZVUzW3CB 1XENu5ACqc06qB+xRGLVCh8= X-Google-Smtp-Source: ABdhPJxog7P3VF21VautBAMxYZ/3o73trUNelQsW8wAG+bh7Wi6vvj2BRI8XRqDepYX6Plvg5agctw== X-Received: by 2002:a17:902:c9d5:b0:138:a025:c944 with SMTP id q21-20020a170902c9d500b00138a025c944mr3135880pld.61.1630390472061; Mon, 30 Aug 2021 23:14:32 -0700 (PDT) Received: from sanitydock.wifi-cloud.jp ([210.160.217.69]) by smtp.gmail.com with ESMTPSA id z7sm1405724pjr.42.2021.08.30.23.14.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 Aug 2021 23:14:31 -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 Subject: [PATCH v9 0/4] drm: update locking for modesetting Date: Tue, 31 Aug 2021 14:13:44 +0800 Message-Id: <20210831061348.97696-1-desmondcheongzx@gmail.com> X-Mailer: git-send-email 2.25.1 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: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Hi, I updated the patch set with some suggestions by Daniel Vetter, and dropped the patches after patch 4 so that we can stick the landing for avoiding races with modesetting rights before dealing with the tricky spinlock. Overall, this series fixes races with modesetting rights, and converts drm_device.master_mutex into master_rwsem. - Patch 1: Fix a potential null ptr dereference in drm_master_release - Patch 2: Convert master_mutex into rwsem (avoids creating a new lock) - Patch 3: Update global mutex locking in the ioctl handler (avoids deadlock when grabbing read lock on master_rwsem in drm_ioctl_kernel) - Patch 4: Plug races with drm modesetting rights v8 -> v9 (suggested by Daniel Vetter): - Dropped patches 5-7 to handle it in another series - Added the appropriate Fixes: tag for the null ptr dereference fix (patch 1) - Create a locked_ioctl bool to clarify locking/unlocking patterns in the ioctl handler (patch 3) - Clarified the kernel doc for master_rwsem (patch 4) v7 -> v8: - Avoid calling drm_lease_held in drm_mode_setcrtc and drm_wait_vblank_ioctl, caught by Intel-gfx CI v6 -> v7: - Export __drm_mode_object_find for loadable modules, caught by the Intel-gfx CI v5 -> v6: - Fix recursive locking on master_rwsem, caught by the Intel-gfx CI v4 -> v5: - Avoid calling drm_file_get_master while holding on to the modeset mutex, caught by the Intel-gfx CI v3 -> v4 (suggested by Daniel Vetter): - Drop a patch that added an unnecessary master_lookup_lock in drm_master_release - Drop a patch that addressed a non-existent race in drm_is_current_master_locked - Remove fixes for non-existent null ptr dereferences - Protect drm_master.magic_map,unique{_len} with master_rwsem instead of master_lookup_lock - Drop the patch that moved master_lookup_lock into struct drm_device - Drop a patch to export task_work_add - Revert the check for the global mutex in the ioctl handler to use drm_core_check_feature instead of drm_dev_needs_global_mutex - Push down master_rwsem locking for selected ioctls to avoid lock hierarchy inversions, and to allow us to hold write locks on master_rwsem instead of flushing readers - Remove master_lookup_lock by replacing it with master_rwsem v2 -> v3: - Unexport drm_master_flush, as suggested by Daniel Vetter. - Merge master_mutex and master_rwsem, as suggested by Daniel Vetter. - Export task_work_add, reported by kernel test robot. - Make master_flush static, reported by kernel test robot. - Move master_lookup_lock into struct drm_device. - Add a missing lock on master_lookup_lock in drm_master_release. - Fix a potential race in drm_is_current_master_locked. - Fix potential null ptr dereferences in drm_{auth, ioctl}. - Protect magic_map,unique{_len} with master_lookup_lock. - Convert master_mutex into a rwsem. - Update global mutex locking in the ioctl handler. v1 -> v2 (suggested by Daniel Vetter): - Address an additional race when drm_open runs. - Switch from SRCU to rwsem to synchronise readers and writers. - Implement drm_master_flush with task_work so that flushes can be queued to run before returning to userspace without creating a new DRM_MASTER_FLUSH ioctl flag. Best wishes, Desmond Desmond Cheong Zhi Xi (4): drm: fix null ptr dereference in drm_master_release drm: convert drm_device.master_mutex into a rwsem drm: lock drm_global_mutex earlier in the ioctl handler drm: avoid races with modesetting rights drivers/gpu/drm/drm_auth.c | 39 ++++++++++++++++------------ drivers/gpu/drm/drm_debugfs.c | 4 +-- drivers/gpu/drm/drm_drv.c | 3 +-- drivers/gpu/drm/drm_file.c | 6 ++--- drivers/gpu/drm/drm_ioctl.c | 49 ++++++++++++++++++++++------------- drivers/gpu/drm/drm_lease.c | 35 +++++++++++++++++-------- include/drm/drm_auth.h | 6 ++--- include/drm/drm_device.h | 16 +++++++++--- include/drm/drm_file.h | 12 ++++----- 9 files changed, 104 insertions(+), 66 deletions(-)