From patchwork Mon Mar 9 12:01:51 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Wilson X-Patchwork-Id: 11426823 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 46BAE14B7 for ; Mon, 9 Mar 2020 12:02:19 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 2EB4320866 for ; Mon, 9 Mar 2020 12:02:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2EB4320866 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=chris-wilson.co.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 0389A6E25C; Mon, 9 Mar 2020 12:02:18 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from fireflyinternet.com (mail.fireflyinternet.com [109.228.58.192]) by gabe.freedesktop.org (Postfix) with ESMTPS id B33D46E25C; Mon, 9 Mar 2020 12:02:15 +0000 (UTC) X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.65.138; Received: from build.alporthouse.com (unverified [78.156.65.138]) by fireflyinternet.com (Firefly Internet (M1)) with ESMTP id 20494481-1500050 for multiple; Mon, 09 Mar 2020 12:01:52 +0000 From: Chris Wilson To: dri-devel@lists.freedesktop.org Subject: [PATCH] drm: Mark up racy check of drm_gem_object.handle_count Date: Mon, 9 Mar 2020 12:01:51 +0000 Message-Id: <20200309120151.7675-1-chris@chris-wilson.co.uk> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mika.kuoppala@linux.intel.com, intel-gfx@lists.freedesktop.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" [ 1715.899800] BUG: KCSAN: data-race in drm_gem_handle_create_tail / drm_gem_object_handle_put_unlocked [ 1715.899838] [ 1715.899861] write to 0xffff8881830f3604 of 4 bytes by task 7834 on cpu 1: [ 1715.899896] drm_gem_handle_create_tail+0x62/0x250 [ 1715.899927] drm_gem_open_ioctl+0xc1/0x160 [ 1715.899956] drm_ioctl_kernel+0xe4/0x120 [ 1715.899981] drm_ioctl+0x297/0x4c7 [ 1715.900003] ksys_ioctl+0x89/0xb0 [ 1715.900027] __x64_sys_ioctl+0x42/0x60 [ 1715.900052] do_syscall_64+0x6e/0x2c0 [ 1715.900079] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 1715.900100] [ 1715.900119] read to 0xffff8881830f3604 of 4 bytes by task 8137 on cpu 0: [ 1715.900149] drm_gem_object_handle_put_unlocked+0x31/0x130 [ 1715.900180] drm_gem_object_release_handle+0x93/0xe0 [ 1715.900208] drm_gem_handle_delete+0x7b/0xe0 [ 1715.900235] drm_gem_close_ioctl+0x61/0x80 [ 1715.900264] drm_ioctl_kernel+0xe4/0x120 [ 1715.900291] drm_ioctl+0x297/0x4c7 [ 1715.900316] ksys_ioctl+0x89/0xb0 [ 1715.900340] __x64_sys_ioctl+0x42/0x60 [ 1715.900363] do_syscall_64+0x6e/0x2c0 [ 1715.900388] entry_SYSCALL_64_after_hwframe+0x44/0xa9 Signed-off-by: Chris Wilson Reviewed-by: Daniel Vetter --- drivers/gpu/drm/drm_gem.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c index a9e4a610445a..37627d06fb06 100644 --- a/drivers/gpu/drm/drm_gem.c +++ b/drivers/gpu/drm/drm_gem.c @@ -218,7 +218,7 @@ drm_gem_object_handle_put_unlocked(struct drm_gem_object *obj) struct drm_device *dev = obj->dev; bool final = false; - if (WARN_ON(obj->handle_count == 0)) + if (WARN_ON(READ_ONCE(obj->handle_count) == 0)) return; /*