4.14-stable review patch. If anyone has any objections, please let me know.
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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 @@ -2783,6 +2783,9 @@ 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.