From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:53618 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729750AbeIXSD1 (ORCPT ); Mon, 24 Sep 2018 14:03:27 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Pingfan Liu , "Rafael J. Wysocki" , Sasha Levin Subject: [PATCH 4.9 043/111] drivers/base: stop new probing during shutdown Date: Mon, 24 Sep 2018 13:52:10 +0200 Message-Id: <20180924113109.233881162@linuxfoundation.org> In-Reply-To: <20180924113103.337261320@linuxfoundation.org> References: <20180924113103.337261320@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Pingfan Liu [ Upstream commit 3297c8fc65af5d40501ea7cddff1b195cae57e4e ] There is a race window in device_shutdown(), which may cause -1. parent device shut down before child or -2. no shutdown on a new probing device. For 1st, taking the following scenario: device_shutdown new plugin device list_del_init(parent_dev); spin_unlock(list_lock); device_add(child) probe child shutdown parent_dev --> now child is on the tail of devices_kset For 2nd, taking the following scenario: device_shutdown new plugin device device_add(dev) device_lock(dev); ... device_unlock(dev); probe dev --> now, the new occurred dev has no opportunity to shutdown To fix this race issue, just prevent the new probing request. With this logic, device_shutdown() is more similar to dpm_prepare(). Signed-off-by: Pingfan Liu Reviewed-by: Rafael J. Wysocki Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/base/core.c | 3 +++ 1 file changed, 3 insertions(+) --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -2072,6 +2072,9 @@ void device_shutdown(void) { struct device *dev, *parent; + wait_for_device_probe(); + device_block_probing(); + spin_lock(&devices_kset->list_lock); /* * Walk the devices list backward, shutting down each in turn.