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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 96B53C433EF for ; Fri, 29 Apr 2022 08:43:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1356015AbiD2IrI (ORCPT ); Fri, 29 Apr 2022 04:47:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46078 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1355964AbiD2Iqn (ORCPT ); Fri, 29 Apr 2022 04:46:43 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id D57A63879C for ; Fri, 29 Apr 2022 01:43:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1651221800; h=from:from:reply-to:subject:subject: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=u/nkZHXCBB5ZrJnB24ro/1pCmNvdbhB1vwTZ80wJLns=; b=eETKrAnUtaKf3YNwNIkU0gjWjnir1lCPhqv2nHuZC4i11qP3ZZWMZkuocy8mkQtQ7BcT5l czLU8lU43hE/CNCpxq1hZ9qeupK0I3eHT71uHbTmVV6VdX18ZPT4+Zwsg4GLvckdJ5Cz2s 49ceEQFfVrk7RjFzixtklAr+mwjVQq0= Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-206-iSx-TqE1PYyrizYWHZKHSg-1; Fri, 29 Apr 2022 04:43:19 -0400 X-MC-Unique: iSx-TqE1PYyrizYWHZKHSg-1 Received: by mail-wm1-f69.google.com with SMTP id m124-20020a1c2682000000b00393fcd2722dso2221519wmm.4 for ; Fri, 29 Apr 2022 01:43:18 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=u/nkZHXCBB5ZrJnB24ro/1pCmNvdbhB1vwTZ80wJLns=; b=XaY2dPu/lFT6NMPZi5s+4KX4jmMSM270XPQx6bvj8HN+8yCMwKpgWcXo5Xwhmd62S/ GCNV6TKUpWUXAXVcyGsayNxCqc3EqtX0NUn7o5NjGLPY7vyzuq4R5vmQZm3FVNfPkreJ Rj9qLbWxa8xszNvnBGI+G90MqUfXLGHKgWhqikajYdXx7SGqidXMSV6lSXQceigClkTr ott98xEfYwU6RrM2AA95Ij+ebn2muftFRRY4QDNtMVjnMncrBfIcmDChQCR/tnq+ARQp vvXkVmmVMwBUaQFmeUAGdXNGIr5xKrygDgugK8ehqm+O77q5B7V6KgIFdfGYlelkqYuv gXWw== X-Gm-Message-State: AOAM532scbOI0Oj6pD6hbTLFslrUAuhzRoA7GKitLGKWjE+Yf0X62ZXV JqwtoAoEJWqpICgSOmtOMQ6D5t68V/9ZVZhioYg06ZpnxVSxgzn1nfszAxi9JXbRNKe+QuFckqe PETuaFkZtpbKzlms4cOrgv8nU3Hl+QTLdSxeKxnATT+o5Hh3nLG/XL+nDNMjSC8t/LFA5HMjDi+ E= X-Received: by 2002:adf:decb:0:b0:20a:c975:8eec with SMTP id i11-20020adfdecb000000b0020ac9758eecmr28946012wrn.438.1651221797515; Fri, 29 Apr 2022 01:43:17 -0700 (PDT) X-Google-Smtp-Source: ABdhPJy8Bnodipm9XVNni3rYsFrTH34G/LMUhH0fq+PeE59BdcIE+fgw0hrkNZbBfqT2Hiuz7RWIbw== X-Received: by 2002:adf:decb:0:b0:20a:c975:8eec with SMTP id i11-20020adfdecb000000b0020ac9758eecmr28945970wrn.438.1651221797201; Fri, 29 Apr 2022 01:43:17 -0700 (PDT) Received: from minerva.home ([92.176.231.205]) by smtp.gmail.com with ESMTPSA id f7-20020a05600c4e8700b00393f1393abfsm7199256wmq.41.2022.04.29.01.43.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 29 Apr 2022 01:43:16 -0700 (PDT) From: Javier Martinez Canillas To: linux-kernel@vger.kernel.org Cc: dri-devel@lists.freedesktop.org, Daniel Vetter , Greg Kroah-Hartman , Thomas Zimmermann , Javier Martinez Canillas , Alex Deucher , Changcheng Deng , Daniel Vetter , Helge Deller , Sam Ravnborg , Zhen Lei , linux-fbdev@vger.kernel.org Subject: [RFC PATCH v4 08/11] fbdev: Fix race between sysfb and framebuffer devices registration Date: Fri, 29 Apr 2022 10:42:50 +0200 Message-Id: <20220429084253.1085911-9-javierm@redhat.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220429084253.1085911-1-javierm@redhat.com> References: <20220429084253.1085911-1-javierm@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The platform devices registered by sysfb match with firmware-based DRM or fbdev drivers, that are used to have early graphics using a framebuffer provided by the system firmware. DRM or fbdev drivers later are probed and remove all conflicting framebuffers, leading to these platform devices for generic drivers to be unregistered. But the current solution has a race, since the sysfb_init() function could be called after a DRM driver is probed and requested to unregister devices for drivers with conflicting framebuffes. To prevent this, disable any future sysfb platform device registration by calling sysfb_disable(), if either a framebuffer device or a DRM device is registered. Since in that case a display will already be present. Suggested-by: Daniel Vetter Signed-off-by: Javier Martinez Canillas --- (no changes since v3) Changes in v3: - Call sysfb_disable() when a fbdev framebuffer is registered rather than when conflicting framebuffers are removed (Thomas Zimmermann). - Drop Daniel Vetter's Reviewed-by tag since patch changed a lot. Changes in v2: - Explain in the commit message that fbmem has to unregister the device as fallback if a driver registered the device itself (Daniel Vetter). - Also explain that fallback in a comment in the code (Daniel Vetter). - Don't encode in fbmem the assumption that sysfb will always register platform devices (Daniel Vetter). - Add a FIXME comment about drivers registering devices (Daniel Vetter). drivers/video/fbdev/core/fbmem.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c index d6ae33990f40..7583296481b0 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -19,6 +19,7 @@ #include #include #include +#include #include #include #include @@ -1903,6 +1904,17 @@ register_framebuffer(struct fb_info *fb_info) ret = do_register_framebuffer(fb_info); mutex_unlock(®istration_lock); + /* + * If a driver registers a framebuffer device, then it can be assumed + * that a display will be present and there is no need for a generic + * driver using the firmware setup system framebuffer. + * + * Disable sysfb and prevent registering simple framebuffer devices, + * but only do it for framebuffers that are not provided by firmware. + */ + if (!(fb_info->flags & FBINFO_MISC_FIRMWARE)) + sysfb_disable(); + return ret; } EXPORT_SYMBOL(register_framebuffer); -- 2.35.1