Changing the cmb_enable attribute of a CCW device can cause a blocked
chzdev process or udev rule. This problem occurs when the device is
offline, cmb_enable is 0, and chzdev is used to set cmb_enable=1 and
online=1 at the same time.
The following call will block:
chzdev 190d -a cmb_enable=1 online=1
The following call will generate a udev rule that will block subsequent
calls to 'udevadm settle':
chzdev 190d -p online=1 cmb_enable=1
Fix this by ensuring that cmb_enable is only set when the CCW device
is not online.
Reported-by: André Wild <wild@linux.vnet.ibm.com>
Signed-off-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
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