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Commit f3eb20fa authored by Jan Glauber's avatar Jan Glauber Committed by Martin Schwidefsky
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[S390] qdio: prevent starvation on PCI devices 



If adapter interrupts are not available and traditional IO interrupts
are used for qdio the inbound tasklet continued to run if new data
arrived. That could possibly block other tasklets scheduled on the
same CPU. If new data arrives schedule the tasklet again instead of
directly processing the new data.

Signed-off-by: default avatarJan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 09a308f3

drivers/s390/cio/qdio_main.c

+7 −3
Original line number Diff line number Diff line
@@ -606,7 +606,7 @@ static void qdio_kick_handler(struct qdio_q *q) 
static void __qdio_inbound_processing(struct qdio_q *q)

{

	qperf_inc(q, tasklet_inbound);

again:



	if (!qdio_inbound_q_moved(q))

		return;
@@ -615,7 +615,10 @@ static void __qdio_inbound_processing(struct qdio_q *q) 
	if (!qdio_inbound_q_done(q)) {

		/* means poll time is not yet over */

		qperf_inc(q, tasklet_inbound_resched);

		goto again;

		if (likely(q->irq_ptr->state != QDIO_IRQ_STATE_STOPPED)) {

			tasklet_schedule(&q->tasklet);

			return;

		}

	}



	qdio_stop_polling(q);
@@ -625,7 +628,8 @@ static void __qdio_inbound_processing(struct qdio_q *q) 
	 */

	if (!qdio_inbound_q_done(q)) {

		qperf_inc(q, tasklet_inbound_resched2);

		goto again;

		if (likely(q->irq_ptr->state != QDIO_IRQ_STATE_STOPPED))

			tasklet_schedule(&q->tasklet);

	}

}