From patchwork Wed Aug 18 07:38:15 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: 12443491 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 8E9F7C4320A for ; Wed, 18 Aug 2021 07:39:30 +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 52D45610E7 for ; Wed, 18 Aug 2021 07:39:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 52D45610E7 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 A0CC36E456; Wed, 18 Aug 2021 07:39:28 +0000 (UTC) Received: from mail-pj1-x102f.google.com (mail-pj1-x102f.google.com [IPv6:2607:f8b0:4864:20::102f]) by gabe.freedesktop.org (Postfix) with ESMTPS id 1E91A6E456; Wed, 18 Aug 2021 07:39:27 +0000 (UTC) Received: by mail-pj1-x102f.google.com with SMTP id j12-20020a17090aeb0c00b00179530520b3so8416787pjz.0; Wed, 18 Aug 2021 00:39:27 -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=e6vxkGEC/5cBQ7RDSXvwNkc+jNWhSIL2gt3cyXjlMy0=; b=i4L99wf64dEZ9LMIjZCdq5HBsL7YO+w6mPeYaGb3CXwuW15cjMopamJ7i+UtFSaN25 z4rZKcLO5w15cg7+P4rlboKjkGbHm2INjwHBCSyIBdvOIIHKMs8iq36Uc2t2HpR4U6DS PeVX7wc1SgqOfwrOtaOMAAAbWfhKZOxgQEPpTAD2DwGmKJuxv9SRbs1jI4DjEfvYP16W GdHdUTB0UPtvFtAUhhcXY6s7AuE8PdIXUBbgVw/jQ8o6Dek7vaaLJH/PPPw6v2VcG07L knSCx6Bi7AAG29YttwsWCAtn2JIenaQ0ncOp7C6cEebcrLUcHzclF2lQeLIn61qhRq9F j7Eg== 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=e6vxkGEC/5cBQ7RDSXvwNkc+jNWhSIL2gt3cyXjlMy0=; b=X12cMjXFilJjrwikMWKsW64Ilc3LI07eBFvPOX2OLSTCm37pZ5sN7lRcpxc7cZHcr2 Y5KVnz241CCqH7jNalXOekxyOOOYJc4z6k5uiwpVAb97G+glSBAVMHY95zN/1KfgQ79o GDo1e6K3cNS+VPEKQ12S6wDLhCO4nfn5r9tiuKfJKheMH/cRo0b6vOv57ibsbRHHdgPK DkkdK3hSevVpL04fBfMdaP+6Dkrllm3ymoI7jsmz2+i/ViHmreBZOvoGs8AhPCBXeJ2L FeMJE4gtJptCeP4GbwlIGsz9x//4P0I2DAk9NbHwn+De6HjEjMBN5t3bDDqOkCNPSzTn AV3g== X-Gm-Message-State: AOAM5338vz8OrTw7aDD5D82dfK9/4NhZXnjgNqtl1+UusPfRhfy9N4sz u9I/tkU+co92Fz3HioS8ne4= X-Google-Smtp-Source: ABdhPJwsjLetmmkwthytXHRAjBgzfi7amhs4Th7JIiNaKTNGuKsh8scjwN6S/Fd61RcIgh641geZBg== X-Received: by 2002:a17:90a:8b12:: with SMTP id y18mr8016646pjn.72.1629272366618; Wed, 18 Aug 2021 00:39:26 -0700 (PDT) Received: from localhost.localdomain ([118.200.190.93]) by smtp.gmail.com with ESMTPSA id u3sm3886729pjr.2.2021.08.18.00.39.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Aug 2021 00:39:26 -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, axboe@kernel.dk, oleg@redhat.com, tglx@linutronix.de, dvyukov@google.com, walter-zh.wu@mediatek.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 v3 0/9] drm, kernel: update locking for DRM Date: Wed, 18 Aug 2021 15:38:15 +0800 Message-Id: <20210818073824.1560124-1-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, The patches in this series are largely fixes and prepwork leading up to the final patch which plugs races with modesetting rights. Most of the fixes don't have bug reports, so comments would be very appreciated. The biggest change from the previous version is that we convert drm_device.master_mutex into master_rwsem, instead of introducing master_rwsem as a third lock. Overall, this series makes the following changes: - Patch 1: Move master_lookup_lock into struct drm_device (enables us to use it to protect attributes accessed by different drm_files) - Patch 2: Add a missing master_lookup_lock in drm_master_release - Patch 3: Fix a potential race in drm_is_current_master_locked - Patch 4: Fix potential null ptr dereferences in drm_{auth, ioctl} - Patch 5: Move magic_map,unique{_len} out from master_mutex's protection into master_lookup_lock's protection (allows us to avoid read_lock -> write_lock deadlocks) - Patch 6: Convert master_mutex into rwsem (avoids creating a new lock) - Patch 7: Update global mutex locking in the ioctl handler (avoids deadlock when grabbing read lock on master_rwsem in drm_ioctl_kernel) - Patch 8: Export task_work_add (enables us to write drm_master_flush) - Patch 9: Plug races with drm modesetting rights 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 (9): drm: move master_lookup_lock into drm_device drm: hold master_lookup_lock when releasing a drm_file's master drm: check for null master in drm_is_current_master_locked drm: fix potential null ptr dereferences in drm_{auth,ioctl} drm: protect magic_map,unique{_len} with master_lookup_lock drm: convert drm_device.master_mutex into a rwsem drm: update global mutex lock in the ioctl handler kernel: export task_work_add drm: avoid races with modesetting rights drivers/gpu/drm/drm_auth.c | 108 ++++++++++++++++++++++++--------- drivers/gpu/drm/drm_debugfs.c | 4 +- drivers/gpu/drm/drm_drv.c | 4 +- drivers/gpu/drm/drm_file.c | 1 - drivers/gpu/drm/drm_internal.h | 1 + drivers/gpu/drm/drm_ioctl.c | 39 +++++++----- drivers/gpu/drm/drm_lease.c | 1 + include/drm/drm_auth.h | 6 +- include/drm/drm_device.h | 27 +++++++-- include/drm/drm_file.h | 20 +++--- kernel/task_work.c | 1 + 11 files changed, 145 insertions(+), 67 deletions(-)