From patchwork Wed Apr 2 08:36:24 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: AngeloGioacchino Del Regno X-Patchwork-Id: 14035651 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 18FC3C28B20 for ; Wed, 2 Apr 2025 08:36:42 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id E174F10E70E; Wed, 2 Apr 2025 08:36:39 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=collabora.com header.i=@collabora.com header.b="jJtvjzke"; dkim-atps=neutral Received: from bali.collaboradmins.com (bali.collaboradmins.com [148.251.105.195]) by gabe.freedesktop.org (Postfix) with ESMTPS id B583910E70D for ; Wed, 2 Apr 2025 08:36:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1743582996; bh=YZUtbjwKJlLT4AAX1HhNOnQe3l9uM8E/KDQX5DNBPxA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jJtvjzkePrE3epTcErtzsKwNRoKXKPqi0GzubbneLO0lXD+G0T0zrYumHCzrbvSp2 4dijltftRVe8YVvbuJhPqedyAR2PQAiJZ5WnFvRXAsrNP31wzotEJ8F3Z66TYHXpoZ mHMJGpHOU9ilJO1dSTktrelmfojd2TUJL0yFsUSaoFzUas5+ilZvXhZD5H8zN/EkWs IlziPlUAYAYBKFIvwASwNdOBRLVfU8PKqW5OPxYEosRJ8HfSeFpRVpfnzJukA20z8I vytk3+H7Hj2ifGDeE1pSBw02qBRrG+1SW2+cfzIG2DU6uTUxmQSV9lkGhqk0+ckKjL eIljs44uywTWw== Received: from IcarusMOD.eternityproject.eu (2-237-20-237.ip236.fastwebnet.it [2.237.20.237]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: kholk11) by bali.collaboradmins.com (Postfix) with ESMTPSA id 762B317E0B0B; Wed, 2 Apr 2025 10:36:35 +0200 (CEST) From: AngeloGioacchino Del Regno To: chunkuang.hu@kernel.org Cc: p.zabel@pengutronix.de, airlied@gmail.com, simona@ffwll.ch, matthias.bgg@gmail.com, angelogioacchino.delregno@collabora.com, nancy.lin@mediatek.com, ck.hu@mediatek.com, djkurtz@chromium.org, littlecvr@chromium.org, bibby.hsieh@mediatek.com, dri-devel@lists.freedesktop.org, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, wenst@chromium.org, kernel@collabora.com Subject: [PATCH v1 1/5] drm/mediatek: mtk_drm_drv: Fix kobject put for mtk_mutex device ptr Date: Wed, 2 Apr 2025 10:36:24 +0200 Message-ID: <20250402083628.20111-2-angelogioacchino.delregno@collabora.com> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250402083628.20111-1-angelogioacchino.delregno@collabora.com> References: <20250402083628.20111-1-angelogioacchino.delregno@collabora.com> 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" This driver is taking a kobject for mtk_mutex only once per mmsys device for each drm-mediatek driver instance, differently from the behavior with other components, but it is decrementing the kobj's refcount in a loop and once per mmsys: this is not right and will result in a refcount_t underflow warning when mediatek-drm returns multiple probe deferrals in one boot (or when manually bound and unbound). Besides that, the refcount for mutex_dev was not decremented for error cases in mtk_drm_bind(), causing another refcount_t warning but this time for overflow, when the failure happens not during driver bind but during component bind. In order to fix one of the reasons why this is happening, remove the put_device(xx->mutex_dev) loop from the mtk_drm_kms_init()'s put_mutex_dev label (and drop the label) and add a single call to correctly free the single incremented refcount of mutex_dev to the mtk_drm_unbind() function to fix the refcount_t underflow. Moreover, add the same call to the error cases in mtk_drm_bind() to fix the refcount_t overflow. Fixes: 1ef7ed48356c ("drm/mediatek: Modify mediatek-drm for mt8195 multi mmsys support") Signed-off-by: AngeloGioacchino Del Regno Reviewed-by: Chen-Yu Tsai --- drivers/gpu/drm/mediatek/mtk_drm_drv.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.c b/drivers/gpu/drm/mediatek/mtk_drm_drv.c index e09578756de0..a8fbccb50c74 100644 --- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c +++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c @@ -464,7 +464,7 @@ static int mtk_drm_kms_init(struct drm_device *drm) ret = drmm_mode_config_init(drm); if (ret) - goto put_mutex_dev; + return ret; drm->mode_config.min_width = 64; drm->mode_config.min_height = 64; @@ -483,7 +483,7 @@ static int mtk_drm_kms_init(struct drm_device *drm) drm->dev_private = private->all_drm_private[i]; ret = component_bind_all(private->all_drm_private[i]->dev, drm); if (ret) - goto put_mutex_dev; + return ret; } /* @@ -576,9 +576,6 @@ static int mtk_drm_kms_init(struct drm_device *drm) err_component_unbind: for (i = 0; i < private->data->mmsys_dev_num; i++) component_unbind_all(private->all_drm_private[i]->dev, drm); -put_mutex_dev: - for (i = 0; i < private->data->mmsys_dev_num; i++) - put_device(private->all_drm_private[i]->mutex_dev); return ret; } @@ -649,8 +646,10 @@ static int mtk_drm_bind(struct device *dev) return 0; drm = drm_dev_alloc(&mtk_drm_driver, dev); - if (IS_ERR(drm)) - return PTR_ERR(drm); + if (IS_ERR(drm)) { + ret = PTR_ERR(drm); + goto err_put_dev; + } private->drm_master = true; drm->dev_private = private; @@ -676,6 +675,8 @@ static int mtk_drm_bind(struct device *dev) drm_dev_put(drm); for (i = 0; i < private->data->mmsys_dev_num; i++) private->all_drm_private[i]->drm = NULL; +err_put_dev: + put_device(private->mutex_dev); return ret; } @@ -688,6 +689,8 @@ static void mtk_drm_unbind(struct device *dev) drm_dev_unregister(private->drm); mtk_drm_kms_deinit(private->drm); drm_dev_put(private->drm); + + put_device(private->mutex_dev); } private->mtk_drm_bound = false; private->drm_master = false;