From patchwork Mon Jan 20 10:00:13 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Gerd Hoffman X-Patchwork-Id: 11341615 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 512CF6C1 for ; Mon, 20 Jan 2020 10:00:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2E26D20684 for ; Mon, 20 Jan 2020 10:00:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="NC42xYd9" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726130AbgATKAX (ORCPT ); Mon, 20 Jan 2020 05:00:23 -0500 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:38341 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726039AbgATKAX (ORCPT ); Mon, 20 Jan 2020 05:00:23 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1579514422; 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; bh=A5GcFGtVAQWVAj/IjmTO+b/muvDYD9pVj8U6MMH/3YE=; b=NC42xYd9N+jq7GCvssjVvkbHqA/j/WnlyYgxAEVF7h9/j3qYiSotPBRrY9gxx3yrWoVuDq za/VWA79JsM+qLwof3q2oXq5rd46pALC6v6cq+6lEbIz+A7O4Vk0FIgG56HeY/nKUlDdA7 7ZOvhKymFcat4x43JEepVu8NMs4fq1s= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-388-YPaqEMN3PyiBcHX6c_McOw-1; Mon, 20 Jan 2020 05:00:19 -0500 X-MC-Unique: YPaqEMN3PyiBcHX6c_McOw-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 39584800590; Mon, 20 Jan 2020 10:00:18 +0000 (UTC) Received: from sirius.home.kraxel.org (ovpn-116-106.ams2.redhat.com [10.36.116.106]) by smtp.corp.redhat.com (Postfix) with ESMTP id C398910013A7; Mon, 20 Jan 2020 10:00:14 +0000 (UTC) Received: by sirius.home.kraxel.org (Postfix, from userid 1000) id 124DB16E36; Mon, 20 Jan 2020 11:00:14 +0100 (CET) From: Gerd Hoffmann To: dri-devel@lists.freedesktop.org Cc: marmarek@invisiblethingslab.com, Gerd Hoffmann , Bartlomiej Zolnierkiewicz , linux-fbdev@vger.kernel.org (open list:FRAMEBUFFER LAYER), linux-kernel@vger.kernel.org (open list) Subject: [PATCH] fbdev: wait for references go away Date: Mon, 20 Jan 2020 11:00:13 +0100 Message-Id: <20200120100014.23488-1-kraxel@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Sender: linux-fbdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@vger.kernel.org Problem: do_unregister_framebuffer() might return before the device is fully cleaned up, due to userspace having a file handle for /dev/fb0 open. Which can result in drm driver not being able to grab resources (and fail initialization) because the firmware framebuffer still holds them. Reportedly plymouth can trigger this. Fix this by trying to wait until all references are gone. Don't wait forever though given that userspace might keep the file handle open. Reported-by: Marek Marczykowski-Górecki Signed-off-by: Gerd Hoffmann --- drivers/video/fbdev/core/fbmem.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c index d04554959ea7..2ea8ac05b065 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -35,6 +35,7 @@ #include #include #include +#include #include @@ -1707,6 +1708,8 @@ static void unlink_framebuffer(struct fb_info *fb_info) static void do_unregister_framebuffer(struct fb_info *fb_info) { + int limit = 100; + unlink_framebuffer(fb_info); if (fb_info->pixmap.addr && (fb_info->pixmap.flags & FB_PIXMAP_DEFAULT)) @@ -1726,6 +1729,10 @@ static void do_unregister_framebuffer(struct fb_info *fb_info) fbcon_fb_unregistered(fb_info); console_unlock(); + /* try wait until all references are gone */ + while (atomic_read(&fb_info->count) > 1 && --limit > 0) + msleep(10); + /* this may free fb info */ put_fb_info(fb_info); }