[S390] tape: Fix race condition in tape block device driver
Due to incorrect function call sequence it can happen that a tape block
request is finished before the request is taken from the block request queue.
The following sequence leads to that condition:
* tapeblock_start_request() -> start CCW program
* Request finishes -> IO interrupt
* tapeblock_end_request()
* end_that_request_last()
If blkdev_dequeue_request() has not been called before end_that_request_last(),
a kernel bug is triggered in end_that_request_last() because the request is
still queued. To solve that problem blkdev_dequeue_request() has to be called
before starting the CCW program.
Signed-off-by: Michael Holzheu <holzheu@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
1 file changed