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=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 ABCDDECDFB8 for ; Wed, 18 Jul 2018 09:19:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6B10F2084E for ; Wed, 18 Jul 2018 09:19:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6B10F2084E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=osadl.org 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 S1730464AbeGRJ4U (ORCPT ); Wed, 18 Jul 2018 05:56:20 -0400 Received: from www.osadl.org ([62.245.132.105]:44635 "EHLO www.osadl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729126AbeGRJ4U (ORCPT ); Wed, 18 Jul 2018 05:56:20 -0400 Received: from debian01.hofrr.at (178.115.242.59.static.drei.at [178.115.242.59] (may be forged)) by www.osadl.org (8.13.8/8.13.8/OSADL-2007092901) with ESMTP id w6I9ErR8002397; Wed, 18 Jul 2018 11:14:53 +0200 From: Nicholas Mc Guire To: Gustavo Padovan Cc: Li Philip , Maarten Lankhorst , Sean Paul , David Airlie , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Nicholas Mc Guire Subject: [PATCH V3] drm: handle error values properly Date: Wed, 18 Jul 2018 11:14:04 +0200 Message-Id: <1531905244-18044-1-git-send-email-hofrat@osadl.org> X-Mailer: git-send-email 2.1.4 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org drm_legacy_ctxbitmap_next() returns idr_alloc() which can return -ENOMEM, -EINVAL or -ENOSPC none of which are -1. since drm_context_t is an unsigned int an intermediate variable is used to handle the error cases, and then cast to drm_context_t after ensuring that the value is >= 0. The explicit cast is to mark the type conversion as intentional. Signed-off-by: Nicholas Mc Guire Reported-by: kbuild test robot Reported-by: Sean Paul Fixes: d530b5f1ca0b ("drm: re-enable error handling") Fixes: 62968144e673 ("drm: convert drm context code to use Linux idr") --- V3: bug in patch - omission to remove old code properly - V3 fixes the original problem as proposed in V2 and drops the excess line. reported by Sean Paul - thanks! V2: The proposed fix in d530b5f1ca0b ("drm: re-enable error handling") actually was ineffective as the negative return value check was against a unsigned int and thus always false as reported by kbuild test robot . The below patch removes that warning and fixes the original problem of missed error handling. drm_context_t is actually just used in a few placed so the type could be changed but it is also exported via tools/include/uapi/drm/drm.h so changing the typedef of drm_context_t could break applications and thus this is not an option. Patch was compile tested with: x86_64_defconfig Patch is against 4.18-rc5 (localversion-next is next-20180718) drivers/gpu/drm/drm_context.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/drm_context.c b/drivers/gpu/drm/drm_context.c index f973d28..ad268c8 100644 --- a/drivers/gpu/drm/drm_context.c +++ b/drivers/gpu/drm/drm_context.c @@ -361,22 +361,25 @@ int drm_legacy_addctx(struct drm_device *dev, void *data, { struct drm_ctx_list *ctx_entry; struct drm_ctx *ctx = data; + int ret; if (!drm_core_check_feature(dev, DRIVER_KMS_LEGACY_CONTEXT) && !drm_core_check_feature(dev, DRIVER_LEGACY)) return -EINVAL; - ctx->handle = drm_legacy_ctxbitmap_next(dev); - if (ctx->handle == DRM_KERNEL_CONTEXT) { + ret = drm_legacy_ctxbitmap_next(dev); + if (ret == DRM_KERNEL_CONTEXT) { /* Skip kernel's context and get a new one. */ - ctx->handle = drm_legacy_ctxbitmap_next(dev); + ret = drm_legacy_ctxbitmap_next(dev); } - DRM_DEBUG("%d\n", ctx->handle); - if (ctx->handle < 0) { + DRM_DEBUG("ctxbitmap is error code %d\n", ret); + if (ret < 0) { DRM_DEBUG("Not enough free contexts.\n"); /* Should this return -EBUSY instead? */ return -ENOMEM; } + /* valid context is >= 0 */ + ctx->handle = (drm_context_t)ret; ctx_entry = kmalloc(sizeof(*ctx_entry), GFP_KERNEL); if (!ctx_entry) { -- 2.1.4