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GenWQE: Support blocking when DDCB queue is busy

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When the GenWQE hardware queue was busy, the driver returned simply
-EBUSY. This caused polling by applications which increased the load
on the already busy system. This change implements the possiblity to
sleep on a waitqueue instead when the DDCB queue is busy. The
requestor is woken up when there is free space on the queue again.
The old way to get -EBUSY is still available if the device is openend
with O_NONBLOCKING. The default is now blocking behavior.

Signed-off-by: Frank Haverkamp <haver@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Frank Haverkamp
2014-09-10 16:37:53 +02:00
committed by Greg Kroah-Hartman
parent 08e4906cc2
commit 1451f41463
4 changed files with 57 additions and 22 deletions
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6
drivers/misc/genwqe/card_debugfs.c
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@@ -244,14 +244,16 @@ static int genwqe_ddcb_info_show(struct seq_file *s, void *unused)
" ddcbs_in_flight: %u\n"
" ddcbs_max_in_flight: %u\n"
" ddcbs_completed: %u\n"
" busy: %u\n"
" return_on_busy: %u\n"
" wait_on_busy: %u\n"
" irqs_processed: %u\n",
queue->ddcb_max, (long long)queue->ddcb_daddr,
(long long)queue->ddcb_daddr +
(queue->ddcb_max * DDCB_LENGTH),
(long long)queue->ddcb_vaddr, queue->ddcbs_in_flight,
queue->ddcbs_max_in_flight, queue->ddcbs_completed,
queue->busy, cd->irqs_processed);
queue->return_on_busy, queue->wait_on_busy,
cd->irqs_processed);
/* Hardware State */
seq_printf(s, " 0x%08x 0x%016llx IO_QUEUE_CONFIG\n"