From f3eb20fafdc10aea0fb13b113ac3b9a3dc9a5dc6 Mon Sep 17 00:00:00 2001
From: Jan Glauber <jang@linux.vnet.ibm.com>
Date: Mon, 17 May 2010 10:00:15 +0200
Subject: [PATCH] [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: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---
drivers/s390/cio/qdio_main.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/drivers/s390/cio/qdio_main.c b/drivers/s390/cio/qdio_main.c
index 1fc81268330e..f4fd6cd4dc08 100644
--- a/drivers/s390/cio/qdio_main.c
+++ b/drivers/s390/cio/qdio_main.c
@@ -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 @@ again:
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 @@ again:
*/
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);
}
}
--
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