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=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT 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 1540AC432BE for ; Wed, 1 Sep 2021 12:29:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E7B2061075 for ; Wed, 1 Sep 2021 12:29:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244428AbhIAMaB (ORCPT ); Wed, 1 Sep 2021 08:30:01 -0400 Received: from mail.kernel.org ([198.145.29.99]:59206 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244411AbhIAM3b (ORCPT ); Wed, 1 Sep 2021 08:29:31 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id DED1961075; Wed, 1 Sep 2021 12:28:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1630499305; bh=/AxiVkp2wPOLGc5o1bO4R4KpoZShQ8u7g5ph4onMxvo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rqUUpDGYETbzQyhfr07WMofUhIKxIIg5WUL3/Ik4U92g2UhSI5qy2FXS2mivQT8ar OmS0PPJmY/sEtU0as48MOINn3mjPTZkqNAz/m6VEV/fcdIv8zZV8EY9SDTcUAf2mgu WTan5Bb8tlK3cUKduJJyQB7iAdwvzvW76g1yuqkY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, =?UTF-8?q?Michel=20D=C3=A4nzer?= , Mark Yacoub , Sean Paul , Sasha Levin Subject: [PATCH 4.14 16/23] drm: Copy drm_wait_vblank to user before returning Date: Wed, 1 Sep 2021 14:27:01 +0200 Message-Id: <20210901122250.310573095@linuxfoundation.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20210901122249.786673285@linuxfoundation.org> References: <20210901122249.786673285@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Mark Yacoub [ Upstream commit fa0b1ef5f7a694f48e00804a391245f3471aa155 ] [Why] Userspace should get back a copy of drm_wait_vblank that's been modified even when drm_wait_vblank_ioctl returns a failure. Rationale: drm_wait_vblank_ioctl modifies the request and expects the user to read it back. When the type is RELATIVE, it modifies it to ABSOLUTE and updates the sequence to become current_vblank_count + sequence (which was RELATIVE), but now it became ABSOLUTE. drmWaitVBlank (in libdrm) expects this to be the case as it modifies the request to be Absolute so it expects the sequence to would have been updated. The change is in compat_drm_wait_vblank, which is called by drm_compat_ioctl. This change of copying the data back regardless of the return number makes it en par with drm_ioctl, which always copies the data before returning. [How] Return from the function after everything has been copied to user. Fixes IGT:kms_flip::modeset-vs-vblank-race-interruptible Tested on ChromeOS Trogdor(msm) Reviewed-by: Michel Dänzer Signed-off-by: Mark Yacoub Signed-off-by: Sean Paul Link: https://patchwork.freedesktop.org/patch/msgid/20210812194917.1703356-1-markyacoub@chromium.org Signed-off-by: Sasha Levin --- drivers/gpu/drm/drm_ioc32.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/drivers/gpu/drm/drm_ioc32.c b/drivers/gpu/drm/drm_ioc32.c index 86105e7f07fc..6773e8f09fc3 100644 --- a/drivers/gpu/drm/drm_ioc32.c +++ b/drivers/gpu/drm/drm_ioc32.c @@ -855,8 +855,6 @@ static int compat_drm_wait_vblank(struct file *file, unsigned int cmd, req.request.sequence = req32.request.sequence; req.request.signal = req32.request.signal; err = drm_ioctl_kernel(file, drm_wait_vblank_ioctl, &req, DRM_UNLOCKED); - if (err) - return err; req32.reply.type = req.reply.type; req32.reply.sequence = req.reply.sequence; @@ -865,7 +863,7 @@ static int compat_drm_wait_vblank(struct file *file, unsigned int cmd, if (copy_to_user(argp, &req32, sizeof(req32))) return -EFAULT; - return 0; + return err; } #if defined(CONFIG_X86) -- 2.30.2