[PATCH 4.4 39/40] s390/qdio: dont touch the dsci in tiqdio_add_input_queues()

From: Greg Kroah-Hartman
Date: Wed Jul 17 2019 - 23:16:40 EST

From: Julian Wiedmann <jwi@xxxxxxxxxxxxx>

commit ac6639cd3db607d386616487902b4cc1850a7be5 upstream.

Current code sets the dsci to 0x00000080. Which doesn't make any sense,
as the indicator area is located in the _left-most_ byte.

Worse: if the dsci is the _shared_ indicator, this potentially clears
the indication of activity for a _different_ device.
tiqdio_thinint_handler() will then have no reason to call that device's
IRQ handler, and the device ends up stalling.

Fixes: d0c9d4a89fff ("[S390] qdio: set correct bit in dsci")
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Julian Wiedmann <jwi@xxxxxxxxxxxxx>
Signed-off-by: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

drivers/s390/cio/qdio_thinint.c | 1 -
1 file changed, 1 deletion(-)

--- a/drivers/s390/cio/qdio_thinint.c
+++ b/drivers/s390/cio/qdio_thinint.c
@@ -80,7 +80,6 @@ void tiqdio_add_input_queues(struct qdio
list_add_rcu(&irq_ptr->input_qs[0]->entry, &tiq_list);
- xchg(irq_ptr->dsci, 1 << 7);

void tiqdio_remove_input_queues(struct qdio_irq *irq_ptr)