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[209.132.180.67]) by mx.google.com with ESMTP id 8-v6si3087198pgs.324.2018.07.18.02.20.45; Wed, 18 Jul 2018 02:21:23 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730316AbeGRJ4U (ORCPT + 99 others); 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 X-Spam-Status: No, score=-1.9 required=6.0 tests=BAYES_00 autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on www.osadl.org 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