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 X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0972FC433E1 for ; Wed, 3 Jun 2020 08:24:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D0C0C20678 for ; Wed, 3 Jun 2020 08:24:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ffwll.ch header.i=@ffwll.ch header.b="diAPk9Nz" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726351AbgFCIYQ (ORCPT ); Wed, 3 Jun 2020 04:24:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55922 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725876AbgFCIYP (ORCPT ); Wed, 3 Jun 2020 04:24:15 -0400 Received: from mail-wm1-x343.google.com (mail-wm1-x343.google.com [IPv6:2a00:1450:4864:20::343]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9BB50C05BD43 for ; Wed, 3 Jun 2020 01:24:14 -0700 (PDT) Received: by mail-wm1-x343.google.com with SMTP id f5so1041309wmh.2 for ; Wed, 03 Jun 2020 01:24:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=date:from:to:cc:subject:message-id:mail-followup-to:references :mime-version:content-disposition:in-reply-to; bh=qRRViGgr/XMXuK899gyJpd+glkMI9g3TUAqhc5bIdms=; b=diAPk9NzqmTTMCUpwWl/9I43wRC0s9YisBeaJ3i/Ao27NvMQV2tq0o/amb5EsgN5Dc m7UOzOkQ1IcJFbc/rP+zbfrn4e78xzB8fxvBTJwqpUCIS+KXHxZzWv0fJ8aqglCSFuUF PsgSO47gzy0i41trTDnIz8ohkR0xLziwSCsy0= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id :mail-followup-to:references:mime-version:content-disposition :in-reply-to; bh=qRRViGgr/XMXuK899gyJpd+glkMI9g3TUAqhc5bIdms=; b=azicj/RUidtys10FpCIWmF0qrzDurus3e70Pe9T45W0QU6B2mM5431X1wCW1zZuGQG d/VP2/ou0Cpw5I+d7axXkJUjXDAUAvI+SjTpqeKeC8+Na8BPAXz7i0Un7PDNKpG0Ujax MOlAHbqkiuEgkOCBHjFXKIgBq2aCEgc1Noz6sRGsNX/ayIPpBwAbd3Br/OQBU0+ddhEb zW8nlOps1wwHnW7WjEi0Zmetv0C9iCXXisjN6z29xwmAr1vR6RBynX7j1PT4v0azOO/F UmhW4bgey+59VZ1u8YyKElmgFsOu5lwpXAkFdkvkX1y2NT8EtIkBmIEQC2yUOxfmhRr2 BSVQ== X-Gm-Message-State: AOAM530WyzrexH8uwkcH+Gi0bYs9LmizmmehIROGBzKMM4RGC9hjcYdE 8A9v4pEla+5LA24CofoXG44hHg== X-Google-Smtp-Source: ABdhPJwF05tJg2U8YAuUBqkP69xy0KO/yd1uPSYB+TFlsp2LQxAA+L8XZMe3ryw0UOWY+kevnffgNw== X-Received: by 2002:a05:600c:1:: with SMTP id g1mr7447279wmc.142.1591172653407; Wed, 03 Jun 2020 01:24:13 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id p10sm2318468wra.78.2020.06.03.01.24.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 03 Jun 2020 01:24:12 -0700 (PDT) Date: Wed, 3 Jun 2020 10:24:11 +0200 From: Daniel Vetter To: Jeykumar Sankaran Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Steve Cohen , seanpaul@chromium.org Subject: Re: [PATCH] drm/connector: notify userspace on hotplug after register complete Message-ID: <20200603082411.GI20149@phenom.ffwll.local> Mail-Followup-To: Jeykumar Sankaran , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Steve Cohen , seanpaul@chromium.org References: <1591155451-10393-1-git-send-email-jsanka@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1591155451-10393-1-git-send-email-jsanka@codeaurora.org> X-Operating-System: Linux phenom 5.6.0-1-amd64 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 02, 2020 at 08:37:31PM -0700, Jeykumar Sankaran wrote: > drm connector notifies userspace on hotplug event prematurely before > late_register and mode_object register completes. This leads to a race > between userspace and kernel on updating the IDR list. So, move the > notification to end of connector register. > > Signed-off-by: Jeykumar Sankaran > Signed-off-by: Steve Cohen Hm on the unregister side we don't have the race, there we remove everything and then send out the uevent. But there the uevent is also generated in a separate step, so I wonder whether we shouldn't do the same for register for symmetry ... Anyway this looks good, nice catch, I'll add cc: stable and merge. -Daniel > --- > drivers/gpu/drm/drm_connector.c | 5 +++++ > drivers/gpu/drm/drm_sysfs.c | 3 --- > 2 files changed, 5 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c > index b1099e1..d877ddc 100644 > --- a/drivers/gpu/drm/drm_connector.c > +++ b/drivers/gpu/drm/drm_connector.c > @@ -27,6 +27,7 @@ > #include > #include > #include > +#include > > #include > > @@ -523,6 +524,10 @@ int drm_connector_register(struct drm_connector *connector) > drm_mode_object_register(connector->dev, &connector->base); > > connector->registration_state = DRM_CONNECTOR_REGISTERED; > + > + /* Let userspace know we have a new connector */ > + drm_sysfs_hotplug_event(connector->dev); > + > goto unlock; > > err_debugfs: > diff --git a/drivers/gpu/drm/drm_sysfs.c b/drivers/gpu/drm/drm_sysfs.c > index 939f003..f0336c8 100644 > --- a/drivers/gpu/drm/drm_sysfs.c > +++ b/drivers/gpu/drm/drm_sysfs.c > @@ -291,9 +291,6 @@ int drm_sysfs_connector_add(struct drm_connector *connector) > return PTR_ERR(connector->kdev); > } > > - /* Let userspace know we have a new connector */ > - drm_sysfs_hotplug_event(dev); > - > if (connector->ddc) > return sysfs_create_link(&connector->kdev->kobj, > &connector->ddc->dev.kobj, "ddc"); > -- > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, > a Linux Foundation Collaborative Project > > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch