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Message-ID: <20180907003816.57852-41-alexander.levin@microsoft.com>
Date: Fri, 7 Sep 2018 00:38:47 +0000
From: Sasha Levin <Alexander.Levin@...rosoft.com>
To: "stable@...r.kernel.org" <stable@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC: Pingfan Liu <kernelfans@...il.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL 4.9 41/43] drivers/base: stop new probing during
shutdown
From: Pingfan Liu <kernelfans@...il.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@...il.com>
Reviewed-by: Rafael J. Wysocki <rafael@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
drivers/base/core.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/base/core.c b/drivers/base/core.c
index a0ed957d738f..f43caad30e1e 100644
--- 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.
--
2.17.1
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