From patchwork Thu Jun 13 05:04:03 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Sam Ravnborg X-Patchwork-Id: 10991105 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D5A13112C for ; Thu, 13 Jun 2019 05:04:14 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B2F4E28B0A for ; Thu, 13 Jun 2019 05:04:14 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A60E228B30; Thu, 13 Jun 2019 05:04:14 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 0312428B0A for ; Thu, 13 Jun 2019 05:04:13 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id CC5CC89272; Thu, 13 Jun 2019 05:04:10 +0000 (UTC) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from asavdk3.altibox.net (asavdk3.altibox.net [109.247.116.14]) by gabe.freedesktop.org (Postfix) with ESMTPS id E247289272; Thu, 13 Jun 2019 05:04:08 +0000 (UTC) Received: from ravnborg.org (unknown [158.248.194.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by asavdk3.altibox.net (Postfix) with ESMTPS id 81A992001E; Thu, 13 Jun 2019 07:04:05 +0200 (CEST) Date: Thu, 13 Jun 2019 07:04:03 +0200 From: Sam Ravnborg To: Rodrigo Siqueira Message-ID: <20190613050403.GA21502@ravnborg.org> References: <20190613021054.cdewdb3azy6zuoyw@smtp.gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190613021054.cdewdb3azy6zuoyw@smtp.gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CMAE-Score: 0 X-CMAE-Analysis: v=2.3 cv=dqr19Wo4 c=1 sm=1 tr=0 a=UWs3HLbX/2nnQ3s7vZ42gw==:117 a=UWs3HLbX/2nnQ3s7vZ42gw==:17 a=jpOVt7BSZ2e4Z31A5e1TngXxSK0=:19 a=IkcTkHD0fZMA:10 a=pGLkceISAAAA:8 a=e5mUnYsNAAAA:8 a=7gkXJVJtAAAA:8 a=QyXUC8HyAAAA:8 a=P-IC7800AAAA:8 a=Jn-_o28iN5fng-a6wa4A:9 a=QEXdDO2ut3YA:10 a=Vxmtnl_E_bksehYqCbjh:22 a=E9Po1WZjFZOl8hwRPBS3:22 a=d3PnA9EDa4IxuAV0gXij:22 Subject: [Intel-gfx] Drop use of DRM_WAIT_ON() [Was: drm/drm_vblank: Change EINVAL by the correct errno] X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Maxime Ripard , kernel-janitors@vger.kernel.org, intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, David Airlie Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" X-Virus-Scanned: ClamAV using ClamSMTP Hi Rodrigo. On Wed, Jun 12, 2019 at 11:10:54PM -0300, Rodrigo Siqueira wrote: > 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 V2: > Daniel Vetter and Chris Wilson > - Replace ENOTTY by EOPNOTSUPP > - Return EINVAL if the parameters are wrong > > Signed-off-by: Rodrigo Siqueira > --- > Update: > Now IGT has a way to validate if a driver has vblank support or not. > See: https://gitlab.freedesktop.org/drm/igt-gpu-tools/commit/2d244aed69165753f3adbbd6468db073dc1acf9A > > 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 0d704bddb1a6..d76a783a7d4b 100644 > --- a/drivers/gpu/drm/drm_vblank.c > +++ b/drivers/gpu/drm/drm_vblank.c > @@ -1578,10 +1578,10 @@ 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; > > if (vblwait->request.type & _DRM_VBLANK_SIGNAL) > - return -EINVAL; > + return -EOPNOTSUPP; > > if (vblwait->request.type & > ~(_DRM_VBLANK_TYPES_MASK | _DRM_VBLANK_FLAGS_MASK | When touching this function, could I ask you to take a look at eliminating the use of DRM_WAIT_ON()? It comes from the deprecated drm_os_linux.h header, and it is only of the few remaining users of DRM_WAIT_ON(). Below you can find my untested first try - where I did an attempt not to change behaviour. Sam commit 17b119b02467356198b57bca9949b146082bcaa1 Author: Sam Ravnborg Date: Thu May 30 09:38:47 2019 +0200 drm/vblank: drop use of DRM_WAIT_ON() DRM_WAIT_ON() is from the deprecated drm_os_linux header and the modern replacement is the wait_event_*. The return values differ, so a conversion is needed to keep the original interface towards userspace. Introduced a switch/case to make code obvious and to allow different debug prints depending on the result. The timeout value of 3 * HZ was translated to 30 msec Signed-off-by: Sam Ravnborg Cc: Maarten Lankhorst Cc: Maxime Ripard Cc: Sean Paul Cc: David Airlie Cc: Daniel Vetter diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c index 0d704bddb1a6..51fc6b106333 100644 --- a/drivers/gpu/drm/drm_vblank.c +++ b/drivers/gpu/drm/drm_vblank.c @@ -31,7 +31,6 @@ #include #include #include -#include #include #include "drm_internal.h" @@ -1668,18 +1667,27 @@ int drm_wait_vblank_ioctl(struct drm_device *dev, void *data, if (req_seq != seq) { DRM_DEBUG("waiting on vblank count %llu, crtc %u\n", req_seq, pipe); - DRM_WAIT_ON(ret, vblank->queue, 3 * HZ, - vblank_passed(drm_vblank_count(dev, pipe), - req_seq) || - !READ_ONCE(vblank->enabled)); + ret = wait_event_interruptible_timeout(vblank->queue, + vblank_passed(drm_vblank_count(dev, pipe), req_seq) || + !READ_ONCE(vblank->enabled), + msecs_to_jiffies(30)); } - if (ret != -EINTR) { + switch (ret) { + case 1: + ret = 0; drm_wait_vblank_reply(dev, pipe, &vblwait->reply); - DRM_DEBUG("crtc %d returning %u to client\n", pipe, vblwait->reply.sequence); - } else { + break; + case 0: + ret = -EBUSY; + drm_wait_vblank_reply(dev, pipe, &vblwait->reply); + DRM_DEBUG("timeout waiting for vblank. crtc %d returning %u to client\n", + pipe, vblwait->reply.sequence); + break; + default: + ret = -EINTR; DRM_DEBUG("crtc %d vblank wait interrupted by signal\n", pipe); }