linux/drivers/s390
Julian Wiedmann 1309982414 s390/qdio: add tighter controls for IRQ polling
Once the call to qdio_establish() has completed, qdio is free to deliver
data IRQs to the device driver's IRQ poll handler.

For qeth (the only qdio driver that currently uses IRQ polling) this is
problematic, since the IRQs can arrive before its NAPI instance is
even registered. Calling napi_schedule() from qeth_qdio_start_poll()
then crashes in various nasty ways.

Until recently qeth checked for IFF_UP to drop such early interrupts,
but that's fragile as well since it doesn't enforce any ordering.

Fix this properly by bringing up the qdio device in IRQS_DISABLED mode,
and have the driver explicitly opt-in to receive data IRQs.
qeth does so from qeth_open(), which kick-starts a NAPI poll and then
calls qdio_start_irq() from qeth_poll().

Also add a matching qdio_stop_irq() in qeth_stop() to switch the qdio
dataplane back into a disabled state.

Fixes: 3d35dbe622 ("s390/qeth: don't check for IFF_UP when scheduling napi")
CC: Qian Cai <cai@lca.pw>
Reported-by: Qian Cai <cai@lca.pw>
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Acked-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-03-09 18:16:06 -07:00
..
block proc: convert everything to "struct proc_ops" 2020-02-04 03:05:26 +00:00
char compat_ioctl: move tape handling into drivers 2019-10-23 17:23:44 +02:00
cio s390/qdio: add tighter controls for IRQ polling 2020-03-09 18:16:06 -07:00
crypto s390/pkey/zcrypt: spelling s/crytp/crypt/ 2020-02-17 18:01:57 +01:00
net s390/qdio: add tighter controls for IRQ polling 2020-03-09 18:16:06 -07:00
scsi s390/qdio: fill SBALEs with absolute addresses 2020-02-19 17:26:32 +01:00
virtio virtio/s390: fix race on airq_areas[] 2019-07-26 13:36:18 +02:00
Makefile s390: remove pointless drivers-y in drivers/s390/Makefile 2019-09-16 13:21:51 +02:00