From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935399AbcLWFrz (ORCPT ); Fri, 23 Dec 2016 00:47:55 -0500 Received: from mga06.intel.com ([134.134.136.31]:29139 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751731AbcLWFry (ORCPT ); Fri, 23 Dec 2016 00:47:54 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.33,392,1477983600"; d="scan'208";a="1085810392" From: changbin.du@intel.com To: daniel.vetter@intel.com Cc: jani.nikula@linux.intel.com, airlied@linux.ie, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, "Du, Changbin" Subject: [PATCH] drm/i915: check if execlist_port is empty before using its content Date: Fri, 23 Dec 2016 13:46:36 +0800 Message-Id: <20161223054636.3924-1-changbin.du@intel.com> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Du, Changbin" This patch fix a crash in function reset_common_ring. In this case, the port[0].request is null when reset the render ring, so a null dereference exception is raised. We need to check execlist_port status first. [ 35.748034] BUG: unable to handle kernel NULL pointer dereference at 0000000000000070 [ 35.749567] IP: [] reset_common_ring+0xbe/0x150 [ 35.749567] Call Trace: [ 35.749567] [] i915_gem_reset+0x150/0x270 [ 35.749567] [] i915_reset+0x8a/0xe0 [ 35.749567] [] i915_reset_and_wakeup+0x131/0x160 [ 35.749567] [] ? gen5_read8+0x110/0x110 [ 35.749567] [] i915_handle_error+0xca/0x5a0 [ 35.749567] [] ? scnprintf+0x3d/0x70 [ 35.749567] [] i915_hangcheck_elapsed+0x213/0x510 [ 35.749567] [] process_one_work+0x15b/0x470 [ 35.749567] [] worker_thread+0x43/0x4d0 [ 35.749567] [] ? process_one_work+0x470/0x470 [ 35.749567] [] ? process_one_work+0x470/0x470 [ 35.749567] [] ? call_usermodehelper_exec_async+0x12e/0x130 [ 35.749567] [] kthread+0xc5/0xe0 [ 35.749567] [] ? kthread_park+0x60/0x60 [ 35.749567] [] ? umh_complete+0x40/0x40 [ 35.749567] [] ret_from_fork+0x22/0x30 Signed-off-by: Changbin Du --- drivers/gpu/drm/i915/intel_lrc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c index 0a09024..81a9b0b 100644 --- a/drivers/gpu/drm/i915/intel_lrc.c +++ b/drivers/gpu/drm/i915/intel_lrc.c @@ -1450,7 +1450,7 @@ static void reset_common_ring(struct intel_engine_cs *engine, /* Catch up with any missed context-switch interrupts */ I915_WRITE(RING_CONTEXT_STATUS_PTR(engine), _MASKED_FIELD(0xffff, 0)); - if (request->ctx != port[0].request->ctx) { + if (!execlists_elsp_idle(engine) && request->ctx != port[0].request->ctx) { i915_gem_request_put(port[0].request); port[0] = port[1]; memset(&port[1], 0, sizeof(port[1])); -- 2.7.4