From 4f325184f2d4c1f2258873b2a333005dc4dfcbc0 Mon Sep 17 00:00:00 2001 From: Jan Glauber Date: Wed, 5 Jan 2011 12:47:49 +0100 Subject: [S390] qdio: prevent race for shared indicators If the shared indicator is used the following race leads to an inbound stall: Device CPU0 CPU1 ======================================================== non-shared DSCI =>1 ALSI => 1 Thin INT ALSI => 0 non-shared DSCI tasklets scheduled shared DSCI => 1 ALSI => 1 shared DSCI => 0 ALSI ? -> set Thin INT ALSI => 0 ALSI was set, shared DSCI => 1 After that no more interrupts occur because the DSCI is still set. Fix that race by only resetting the shared DSCI if it was actually set so the tasklets for all shared devices are scheduled and will run after the interrupt. Signed-off-by: Jan Glauber Signed-off-by: Martin Schwidefsky --- drivers/s390/cio/qdio_main.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'drivers/s390/cio/qdio_main.c') diff --git a/drivers/s390/cio/qdio_main.c b/drivers/s390/cio/qdio_main.c index 194ea8c182b2..6621de94f3ad 100644 --- a/drivers/s390/cio/qdio_main.c +++ b/drivers/s390/cio/qdio_main.c @@ -1552,7 +1552,7 @@ int qdio_start_irq(struct ccw_device *cdev, int nr) WARN_ON(queue_irqs_enabled(q)); - if (!shared_ind(q->irq_ptr)) + if (!shared_ind(q->irq_ptr->dsci)) xchg(q->irq_ptr->dsci, 0); qdio_stop_polling(q); @@ -1562,7 +1562,7 @@ int qdio_start_irq(struct ccw_device *cdev, int nr) * We need to check again to not lose initiative after * resetting the ACK state. */ - if (!shared_ind(q->irq_ptr) && *q->irq_ptr->dsci) + if (!shared_ind(q->irq_ptr->dsci) && *q->irq_ptr->dsci) goto rescan; if (!qdio_inbound_q_done(q)) goto rescan; -- cgit v1.2.2