linux/drivers/s390
Julian Wiedmann 901e3f49fa s390/qeth: avoid control IO completion stalls
For control IO, qeth currently tracks the index of the buffer that it
expects to complete the next IO on each qeth_channel. If the channel
presents an IRQ while this buffer has not yet completed, no completion
processing for _any_ completed buffer takes place.
So if the 'next buffer' is skipped for any sort of reason* (eg. when it
is released due to error conditions, before the IO is started), the
buffer obviously won't switch to PROCESSED until it is eventually
allocated for a _different_ IO and completes.
Until this happens, all completion processing on that channel stalls
and pending requests possibly time out.

As a fix, remove the whole 'next buffer' logic and simply process any
IO buffer right when it completes. A channel will never have more than
one IO pending, so there's no risk of processing out-of-sequence.

*Note: currently just one location in the code really handles this problem,
       by advancing the 'next' index manually.

Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-04-22 14:42:31 -04:00
..
block s390: remove couple of duplicate includes 2018-04-16 09:10:24 +02:00
char s390/sclp: avoid potential usage of uninitialized value 2018-04-16 09:10:17 +02:00
cio s390: assume diag308 set always works 2018-04-10 07:38:59 +02:00
crypto s390/zcrypt: Support up to 256 crypto adapters. 2018-04-11 10:36:27 +02:00
net s390/qeth: avoid control IO completion stalls 2018-04-22 14:42:31 -04:00
scsi bsg-lib: introduce a timeout field in struct bsg_job 2018-03-13 11:40:21 -06:00
virtio virtio/s390: implement PM operations for virtio_ccw 2018-02-14 14:34:09 +02:00
Makefile kbuild: rename built-in.o to built-in.a 2018-03-26 02:01:19 +09:00