The 'expires' value of a ccw requests defines how long the device
driver should wait for a response from the evice after the request has
been submitted to the channel subsystem. After the expiration time
(e.g. 30 seconds) the waiting request will be cancelled and started
again. This protects the DASD devices from beeing blocked by errors
that cause the answering I/O interrupt to be lost.
In case of error recovery requests, this 'expires' value used to be
set to 0, so in case of a lost interrupt, such a recovery request
would never expire and block the device. To prevent this kind of
problem, all recovery requests need to have an expires value > 0 as
well. If not specified otherwise, this should be the same expires
value as for the original request.
Signed-off-by: Stefan Weinhuber <wein@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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