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zdev: Fix blocking chzdev call/udev rules with cmb_enable

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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>
This commit is contained in:
Peter Oberparleiter
2018-03-07 14:11:25 +00:00
committed by Jan Höppner
parent 156450f359
commit d82f5e1f49
1 changed files with 1 additions and 0 deletions
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1
zdev/src/ccw.c
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@@ -73,6 +73,7 @@ struct attrib ccw_attr_cmb_enable = {
" 1: Data collection is enabled (rewrite 1 to reset data)\n",
.rewrite = 1,
.defval = "0",
.order_cmp = ccw_offline_only_order_cmp,
.accept = ACCEPT_ARRAY(ACCEPT_RANGE(0, 1)),
};