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=-5.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham 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 70132C04EBD for ; Tue, 16 Oct 2018 16:38:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 18BD42089E for ; Tue, 16 Oct 2018 16:38:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=ffwll.ch header.i=@ffwll.ch header.b="Q9cLjCYw" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 18BD42089E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ffwll.ch Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727332AbeJQA3u (ORCPT ); Tue, 16 Oct 2018 20:29:50 -0400 Received: from mail-ed1-f68.google.com ([209.85.208.68]:36155 "EHLO mail-ed1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726778AbeJQA3u (ORCPT ); Tue, 16 Oct 2018 20:29:50 -0400 Received: by mail-ed1-f68.google.com with SMTP id c26-v6so21998300edt.3 for ; Tue, 16 Oct 2018 09:38:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=sender:date:from:to:cc:subject:message-id:mail-followup-to :references:mime-version:content-disposition :content-transfer-encoding:in-reply-to:user-agent; bh=OGbpf6VY1dRc7YQGUwrKOJ0hbw3rVdNYxq4/XpQZ8o0=; b=Q9cLjCYw1S/ef6UKh25jQMjhy8qgP7DsVB3g1Y2/rnLWxFL/or/T9YvhqTjfMQxn4R SY7Q68k7OaAISAysMFOQfP1i5nNUP3VIt5FZ2WS+JKcFkzMXRMDNuQcYdXUFS/QY6kbS BbqQZR1Yu5rTAhyoV4C9SZuje0zi57Qo3AUyA= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :mail-followup-to:references:mime-version:content-disposition :content-transfer-encoding:in-reply-to:user-agent; bh=OGbpf6VY1dRc7YQGUwrKOJ0hbw3rVdNYxq4/XpQZ8o0=; b=h7L8Y9v4xZE7UaV31hsxrL5QjerzDdJCVK91laUn8nhYx+0gNod7+dphi8sNlH1XEP KNIu6AkQ8GhAM9PgivuM5BVSqPdjqVi4k855k8zCrw2atXA4g0/02+oosfYWfGYHVmxE ff3hH1wX7YkcBK3mX8jt5TSexyO3w8Hl37ca/DGcxSPRdVsW/i5IKakgg0dcvcFePERf htGsBog0mDZ8b6VJqYzj35ACBjko9a0tOvYoeRCRczUAU2SOhTSham9/snu84gHf5OTy t+NpkDtlpV1sgLRsR48PNMQENeH8CUqbCjsMyH84jnPVeymqD1FZ1sQNgcUSyXHdtmiP pZjA== X-Gm-Message-State: ABuFfoiMtgPTmcvFzJxHVZj7d2vbq5NCmIPfgeFd1g41FEu49ICtvB2G 0l65OBLbXdCW+6bvwcghLJhcng== X-Google-Smtp-Source: ACcGV62ts3Uy5/cKZpqd67aT5SKSm7laF375T2Yu9QEyX+UCVaeqVHO4jC54Axoek744VPv/KGH6iA== X-Received: by 2002:a50:b68b:: with SMTP id d11-v6mr31309579ede.283.1539707914705; Tue, 16 Oct 2018 09:38:34 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:569e:0:3106:d637:d723:e855]) by smtp.gmail.com with ESMTPSA id m11sm5217425edv.90.2018.10.16.09.38.33 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 16 Oct 2018 09:38:33 -0700 (PDT) Date: Tue, 16 Oct 2018 18:38:31 +0200 From: Daniel Vetter To: Maarten Lankhorst Cc: Rodrigo Siqueira , Gustavo Padovan , Sean Paul , David Airlie , Daniel Vetter , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org Subject: Re: [PATCH v2] drm/drm_vblank: Change EINVAL by the correct errno Message-ID: <20181016163831.GA31561@phenom.ffwll.local> Mail-Followup-To: Maarten Lankhorst , Rodrigo Siqueira , Gustavo Padovan , Sean Paul , David Airlie , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org References: <20181015170529.dgzpbm37hbuvqatc@smtp.gmail.com> <57b40f9f-24d2-27de-4895-5a76ff267643@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <57b40f9f-24d2-27de-4895-5a76ff267643@linux.intel.com> X-Operating-System: Linux phenom 4.14.0-1-amd64 User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 16, 2018 at 03:36:20PM +0200, Maarten Lankhorst wrote: > Op 15-10-18 om 19:05 schreef Rodrigo Siqueira: > > For historical reason, the function drm_wait_vblank_ioctl always return > > -EINVAL if something gets wrong. This scenario limits the flexibility > > for the userspace make detailed verification of the problem and take > > some action. In particular, the validation of “if (!dev->irq_enabled)” > > in the drm_wait_vblank_ioctl is responsible for checking if the driver > > support vblank or not. If the driver does not support VBlank, the > > function drm_wait_vblank_ioctl returns EINVAL which does not represent > > the real issue; this patch changes this behavior by return EOPNOTSUPP. > > Additionally, some operations are unsupported by this function, and > > returns EINVAL; this patch also changes the return value to EOPNOTSUPP > > in this case. Lastly, the function drm_wait_vblank_ioctl is invoked by > > libdrm, which is used by many compositors; because of this, it is > > important to check if this change breaks any compositor. In this sense, > > the following projects were examined: > > > > * Drm-hwcomposer > > * Kwin > > * Sway > > * Wlroots > > * Wayland-core > > * Weston > > * Xorg (67 different drivers) > > > > For each repository the verification happened in three steps: > > > > * Update the main branch > > * Look for any occurrence "drmWaitVBlank" with the command: > > git grep -n "drmWaitVBlank" > > * Look in the git history of the project with the command: > > git log -SdrmWaitVBlank > > > > Finally, none of the above projects validate the use of EINVAL which > > make safe, at least for these projects, to change the return values. > > > > Change since V1: > > Daniel Vetter and Chris Wilson > > - Replace ENOTTY by EOPNOTSUPP > > - Return EINVAL if the parameters are wrong > > > > Signed-off-by: Rodrigo Siqueira > > --- > > drivers/gpu/drm/drm_vblank.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c > > index 98e091175921..80f5a3bb427e 100644 > > --- a/drivers/gpu/drm/drm_vblank.c > > +++ b/drivers/gpu/drm/drm_vblank.c > > @@ -1533,10 +1533,10 @@ int drm_wait_vblank_ioctl(struct drm_device *dev, void *data, > > unsigned int flags, pipe, high_pipe; > > > > if (!dev->irq_enabled) > > - return -EINVAL; > > + return -EOPNOTSUPP; > Change to -EIO? > > If userspace would ever print this out, it would print the following > confusing message to userspace: > "Operation not supported on transport endpoint" You're a bit late, EOPNOTSUPP is not established already in upstream for this. And -EIO is taken already for "the gpu is dead". > > > > if (vblwait->request.type & _DRM_VBLANK_SIGNAL) > > - return -EINVAL; > > + return -EOPNOTSUPP; > I would keep this -EINVAL, tbh and making it part of the below if statement.. We discussed this, it's different: This here is an ioctl flag that's no longer supported, the below is just an invalid request. Hence different errno. I think you missed a bit with your bikeshed :-) -Daniel > > if (vblwait->request.type & > > ~(_DRM_VBLANK_TYPES_MASK | _DRM_VBLANK_FLAGS_MASK | > > Cheers, > > Maarten > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch