From patchwork Mon Sep 25 07:26:38 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Zimmermann X-Patchwork-Id: 13397365 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 92C36CE7A89 for ; Mon, 25 Sep 2023 07:33:43 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id C796610E1EB; Mon, 25 Sep 2023 07:33:27 +0000 (UTC) Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by gabe.freedesktop.org (Postfix) with ESMTPS id 89FE910E156; Mon, 25 Sep 2023 07:33:20 +0000 (UTC) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id EFC2D1F460; Mon, 25 Sep 2023 07:33:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1695627198; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=wKbREabpY/tMUbfIokDvQuIXsWrd55d6jcXVepokFiI=; b=aiF8zAOND3Z0/kKjUb+euMM+s+EyBt4DIl3TMXeRrFrG94lKbqgfDujl1aRUzukHTTAGHu erVhT4j9LuOI296rHJV6zko4ERJXiRyd69N31+SHRMpz5e0ysCSfxVShnKNW8+8K8bcMW5 bXdALi0K4nCXr3nHOWxSK4iCt5JmHT4= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1695627198; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=wKbREabpY/tMUbfIokDvQuIXsWrd55d6jcXVepokFiI=; b=ijPcAaWyeKBKU3BMlXcaX7De83TqNkQ4PFPgtHnqXn18h6G23rckO+A7C+SGlpbKsm3698 KtXhUeWHXQnLb8Ag== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id AAC8E1358F; Mon, 25 Sep 2023 07:33:18 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id GCHpKL43EWVyPQAAMHmgww (envelope-from ); Mon, 25 Sep 2023 07:33:18 +0000 From: Thomas Zimmermann To: jani.nikula@linux.intel.com, joonas.lahtinen@linux.intel.com, rodrigo.vivi@intel.com, tvrtko.ursulin@linux.intel.com, ville.syrjala@linux.intel.com, imre.deak@intel.com, tejas.upadhyay@intel.com, javierm@redhat.com, airlied@gmail.com, daniel@ffwll.ch Date: Mon, 25 Sep 2023 09:26:38 +0200 Message-ID: <20230925073315.11627-3-tzimmermann@suse.de> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20230925073315.11627-1-tzimmermann@suse.de> References: <20230925073315.11627-1-tzimmermann@suse.de> MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH 2/7] drm/client: Do not acquire module reference X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: intel-gfx@lists.freedesktop.org, Thomas Zimmermann , dri-devel@lists.freedesktop.org Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" Do not acquire a reference on the module that provides a client's callback functions in drm_client_init(). The additional reference prevents the user from unloading the callback functions' module and thus creating dangling pointers. This is only necessary if there is no direct dependency between the caller of drm_client_init() and the provider of the callbacks in struct drm_client_funcs. If this case ever existed, it has been removed from the DRM code. Callers of drm_client_init() also provide the callback implementation. The lifetime of the clients is tied to the dependency chain's outer-most module, which is the hardware's DRM driver. Before client helpers could be unloaded, the driver module would have to be unloaded, which also unregisters all clients. Driver modules that set up DRM clients can now be unloaded. Signed-off-by: Thomas Zimmermann --- drivers/gpu/drm/drm_client.c | 12 +----------- 1 file changed, 1 insertion(+), 11 deletions(-) diff --git a/drivers/gpu/drm/drm_client.c b/drivers/gpu/drm/drm_client.c index 2762572f286e7..b49f91b5d4b27 100644 --- a/drivers/gpu/drm/drm_client.c +++ b/drivers/gpu/drm/drm_client.c @@ -5,7 +5,6 @@ #include #include -#include #include #include #include @@ -84,16 +83,13 @@ int drm_client_init(struct drm_device *dev, struct drm_client_dev *client, if (!drm_core_check_feature(dev, DRIVER_MODESET) || !dev->driver->dumb_create) return -EOPNOTSUPP; - if (funcs && !try_module_get(funcs->owner)) - return -ENODEV; - client->dev = dev; client->name = name; client->funcs = funcs; ret = drm_client_modeset_create(client); if (ret) - goto err_put_module; + return ret; ret = drm_client_open(client); if (ret) @@ -105,10 +101,6 @@ int drm_client_init(struct drm_device *dev, struct drm_client_dev *client, err_free: drm_client_modeset_free(client); -err_put_module: - if (funcs) - module_put(funcs->owner); - return ret; } EXPORT_SYMBOL(drm_client_init); @@ -177,8 +169,6 @@ void drm_client_release(struct drm_client_dev *client) drm_client_modeset_free(client); drm_client_close(client); drm_dev_put(dev); - if (client->funcs) - module_put(client->funcs->owner); } EXPORT_SYMBOL(drm_client_release);