From 13099824145a599c282dd9193d10577250f18382 Mon Sep 17 00:00:00 2001 From: Julian Wiedmann Date: Fri, 6 Mar 2020 09:13:10 +0100 Subject: [PATCH] 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: 3d35dbe6224e ("s390/qeth: don't check for IFF_UP when scheduling napi") CC: Qian Cai Reported-by: Qian Cai Signed-off-by: Julian Wiedmann Acked-by: Vasily Gorbik Signed-off-by: David S. Miller --- drivers/s390/cio/qdio_setup.c | 11 +++++++++-- drivers/s390/net/qeth_core_main.c | 5 ++--- 2 files changed, 11 insertions(+), 5 deletions(-) diff --git a/drivers/s390/cio/qdio_setup.c b/drivers/s390/cio/qdio_setup.c index e115623..66e4bdc 100644 --- a/drivers/s390/cio/qdio_setup.c +++ b/drivers/s390/cio/qdio_setup.c @@ -224,8 +224,15 @@ static void setup_queues(struct qdio_irq *irq_ptr, setup_queues_misc(q, irq_ptr, qdio_init->input_handler, i); q->is_input_q = 1; - q->u.in.queue_start_poll = qdio_init->queue_start_poll_array ? - qdio_init->queue_start_poll_array[i] : NULL; + if (qdio_init->queue_start_poll_array && + qdio_init->queue_start_poll_array[i]) { + q->u.in.queue_start_poll = + qdio_init->queue_start_poll_array[i]; + set_bit(QDIO_QUEUE_IRQS_DISABLED, + &q->u.in.queue_irq_state); + } else { + q->u.in.queue_start_poll = NULL; + } setup_storage_lists(q, irq_ptr, input_sbal_array, i); input_sbal_array += QDIO_MAX_BUFFERS_PER_Q; diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c index fdc5054..37c17ad 100644 --- a/drivers/s390/net/qeth_core_main.c +++ b/drivers/s390/net/qeth_core_main.c @@ -6582,9 +6582,6 @@ int qeth_open(struct net_device *dev) QETH_CARD_TEXT(card, 4, "qethopen"); - if (qdio_stop_irq(CARD_DDEV(card), 0) < 0) - return -EIO; - card->data.state = CH_STATE_UP; netif_tx_start_all_queues(dev); @@ -6634,6 +6631,8 @@ int qeth_stop(struct net_device *dev) } napi_disable(&card->napi); + qdio_stop_irq(CARD_DDEV(card), 0); + return 0; } EXPORT_SYMBOL_GPL(qeth_stop); -- 2.7.4