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 5BBC4C11F68 for ; Wed, 30 Jun 2021 14:55:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 408746143B for ; Wed, 30 Jun 2021 14:55:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235725AbhF3O6Y (ORCPT ); Wed, 30 Jun 2021 10:58:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32774 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235177AbhF3O6W (ORCPT ); Wed, 30 Jun 2021 10:58:22 -0400 Received: from mail-pj1-x102a.google.com (mail-pj1-x102a.google.com [IPv6:2607:f8b0:4864:20::102a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 59BD3C061768; Wed, 30 Jun 2021 07:55:52 -0700 (PDT) Received: by mail-pj1-x102a.google.com with SMTP id pf4-20020a17090b1d84b029016f6699c3f2so4479906pjb.0; Wed, 30 Jun 2021 07:55:52 -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=7TptsW5OQ3GR+u/tITdCBbefhDZ5KPjgj9kl0duGn/0=; b=jQMcYfmo4WOy762+XlXq7rREStvEn1K/QbSMcETHOaImZDMR6TV8ygdhXa4cDZQhA2 SFEOD/Ken2OZVNKzwUGscD4H1Wn0L6dYPUVM3B+ON0AfnAhbAEeh8lb4Wu8C36bsnU59 SA0z3caBP7tlt9vECTP+aPMUnQlX37E5u4gu0vG7NEn7J5zFwhqgVf+biiNr8aCnVBln bzCgj9RFB/v0jMtUFdOgjkhanDDI6HmeUoKdFqohEWrZKz8tf01y6CI/yXjVhp6OMaef 3CwRMFzak934JJTSNqZdrAnmp3iTkOHLfRpmQhpmffIbDOtF8LQgDL8nJdEHtAWdbQAb mXlg== 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=7TptsW5OQ3GR+u/tITdCBbefhDZ5KPjgj9kl0duGn/0=; b=jJtLM5pD4ZTiKQNQ0x+yiH7VHOryo0uAYQ+r6kXrZZ2aQfeTRf7sHY4X04JTaWWnwZ xqZhHttXNym0bnXc7+byNamBLGqTv/gnhUnmF5wTTj4OuSDl41RxXByP9Ji/DnQaHbZW 85SlxgXc1jiX+pxJ7W9E3mAmvdexiL26kXO4cMt6M26G+Vu+3MbaJipwD8G3VNJvMZkN lL4mJc1Z+c25QIjjATdvTsL4ZwF5EqjZPPvJXBZM/ahhvUS77jGqvP36SvpL+5q4P1uC ShzknBvaiZ8nYcpO3Kg/foeuTlCticJePAKd8Rp0owkS/rKFfFQ+q7OEmV3ZND68EUYP 0D2w== X-Gm-Message-State: AOAM532IPMc8wD+f+1I2VmgdrX1qlohE1UFrN9/ub3D30KMSelv9cA3i g0H5+KZxcID33oWEFZh6Fis= X-Google-Smtp-Source: ABdhPJzlakShd++NdtFkoi8/aMmEkS+Gpz+BqRr8GgeXQvHyNR1eldpRvcZf+RI+EEcYEAP/mljnpw== X-Received: by 2002:a17:90b:19d4:: with SMTP id nm20mr4798973pjb.134.1625064951982; Wed, 30 Jun 2021 07:55:51 -0700 (PDT) Received: from localhost.localdomain ([118.200.190.93]) by smtp.gmail.com with ESMTPSA id d13sm7157234pjr.49.2021.06.30.07.55.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Jun 2021 07:55:51 -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, intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org, skhan@linuxfoundation.org, gregkh@linuxfoundation.org, linux-kernel-mentees@lists.linuxfoundation.org, emil.l.velikov@gmail.com Subject: [PATCH v6 2/4] drm: avoid circular locks in __drm_mode_object_find Date: Wed, 30 Jun 2021 22:54:02 +0800 Message-Id: <20210630145404.5958-3-desmondcheongzx@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210630145404.5958-1-desmondcheongzx@gmail.com> References: <20210630145404.5958-1-desmondcheongzx@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In a future patch, _drm_lease_held will dereference drm_file->master only after making a call to drm_file_get_master which increments the reference count of drm_file->master while holding a lock on drm_device.master_mutex. In preparation for this, the call to _drm_lease_held should be moved out from the section locked by &dev->mode_config.idr_mutex. This avoids inverting the lock hierarchy for &dev->master_mutex --> &dev->mode_config.idr_mutex Signed-off-by: Desmond Cheong Zhi Xi --- drivers/gpu/drm/drm_mode_object.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/drm_mode_object.c b/drivers/gpu/drm/drm_mode_object.c index b26588b52795..63d35f1f98dd 100644 --- a/drivers/gpu/drm/drm_mode_object.c +++ b/drivers/gpu/drm/drm_mode_object.c @@ -146,16 +146,18 @@ struct drm_mode_object *__drm_mode_object_find(struct drm_device *dev, if (obj && obj->id != id) obj = NULL; - if (obj && drm_mode_object_lease_required(obj->type) && - !_drm_lease_held(file_priv, obj->id)) - obj = NULL; - if (obj && obj->free_cb) { if (!kref_get_unless_zero(&obj->refcount)) obj = NULL; } mutex_unlock(&dev->mode_config.idr_mutex); + if (obj && drm_mode_object_lease_required(obj->type) && + !_drm_lease_held(file_priv, obj->id)) { + drm_mode_object_put(obj); + obj = NULL; + } + return obj; } -- 2.25.1