From patchwork Wed Nov 6 10:48:27 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luca Ceresoli X-Patchwork-Id: 13864362 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 47CCDD44D46 for ; Wed, 6 Nov 2024 10:48:52 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 566E710E6B9; Wed, 6 Nov 2024 10:48:50 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=bootlin.com header.i=@bootlin.com header.b="kaUmYTxC"; dkim-atps=neutral Received: from relay3-d.mail.gandi.net (relay3-d.mail.gandi.net [217.70.183.195]) by gabe.freedesktop.org (Postfix) with ESMTPS id 48F6D10E6B6 for ; Wed, 6 Nov 2024 10:48:46 +0000 (UTC) Received: by mail.gandi.net (Postfix) with ESMTPSA id 6DAC160003; Wed, 6 Nov 2024 10:48:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1730890125; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ZWsYONnEgvEeIa9tipWPBTuf84MWmW0KPLgHIvkZDok=; b=kaUmYTxCnAY2Yaz8+lF+h/n9rzbIibLHfOtbjYi0RxCWz7kJHEgqIzosrye/v3wAiLSPLW gO9t/5T1tl6xNTSs2mPVzehbbookhUgglKSomQsH7cMyi+oTmW7jhhYhmKo8xYKRGsT7vQ lM81A82fyV1da9oFru9YDUO9/fIIOVB1h++XisPbFFxHmc9O7c78qxbpzwbYSCYbVD2/kV 3yUPLJw07eInHnS1s2gLJ8F2QK8kmW01qB5Gwy/2GOIb6wVy9EB0EzHSXbB4/F5kwkSvTO rAdLAmsK2Beluk6zyorHqG8v54mwsNjHmEUwfihpS+VpYxgbzWfK5mVI2gC+Tg== From: Luca Ceresoli Date: Wed, 06 Nov 2024 11:48:27 +0100 Subject: [PATCH v2 4/4] drm/connector: warn when cleaning up a refcounted connector MIME-Version: 1.0 Message-Id: <20241106-drm-small-improvements-v2-4-f6e2aef86719@bootlin.com> References: <20241106-drm-small-improvements-v2-0-f6e2aef86719@bootlin.com> In-Reply-To: <20241106-drm-small-improvements-v2-0-f6e2aef86719@bootlin.com> To: Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter Cc: Thomas Petazzoni , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Luca Ceresoli X-Mailer: b4 0.14.2 X-GND-Sasl: luca.ceresoli@bootlin.com 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" Calling drm_connector_cleanup() should only be done via the free_cb => .destroy path, which cleans up the struct drm_connector only when the refcount drops to zero. A cleanup done with a refcount higher than 0 can result from buggy code, e.g. by doing cleanup directly in the drivers teardown code. Serious trouble can happen if this happens, so warn about it. Signed-off-by: Luca Ceresoli --- drivers/gpu/drm/drm_connector.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c index fc35f47e2849ed6786d6223ac9c69e1c359fc648..e0bf9c490af43055de4caaee1580a4befbd608c5 100644 --- a/drivers/gpu/drm/drm_connector.c +++ b/drivers/gpu/drm/drm_connector.c @@ -624,6 +624,12 @@ void drm_connector_cleanup(struct drm_connector *connector) struct drm_device *dev = connector->dev; struct drm_display_mode *mode, *t; + /* + * Cleanup must happen when the last ref is put, via the + * drm_connector_free() callback. + */ + WARN_ON(drm_mode_object_read_refcount(&connector->base) != 0); + /* The connector should have been removed from userspace long before * it is finally destroyed. */