lkml.org 
[lkml]   [2018]   [Sep]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 4.18 086/235] drivers/base: stop new probing during shutdown
Date
4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Pingfan Liu <kernelfans@gmail.com>

[ 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 <kernelfans@gmail.com>
Reviewed-by: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/base/core.c | 3 +++
1 file changed, 3 insertions(+)

--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -2809,6 +2809,9 @@ 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.

\
 
 \ /
  Last update: 2018-09-24 14:51    [W:0.884 / U:0.852 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site