[PATCH 5.10 101/157] s390/qeth: schedule TX NAPI on QAOB completion

Greg Kroah-Hartman
2021-03-22T12:49:29Z

From: Julian Wiedmann <jwi@linux.ibm.com>

[ Upstream commit 3e83d467a08e25b27c44c885f511624a71c84f7c ]

When a QAOB notifies us that a pending TX buffer has been delivered, the
actual TX completion processing by qeth_tx_complete_pending_bufs()
is done within the context of a TX NAPI instance. We shouldn't rely on
this instance being scheduled by some other TX event, but just do it
ourselves.

qeth_qdio_handle_aob() is called from qeth_poll(), ie. our main NAPI
instance. To avoid touching the TX queue's NAPI instance
before/after it is (un-)registered, reorder the code in qeth_open()
and qeth_stop() accordingly.

Fixes: 0da9581ddb0f ("qeth: exploit asynchronous delivery of storage blocks")
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/s390/net/qeth_core_main.c | 18 ++++++++++++------
1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c
index 03f96177e58e..4d51c4ace8ea 100644
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -470,6 +470,7 @@ static void qeth_qdio_handle_aob(struct qeth_card *card,
struct qaob *aob;
struct qeth_qdio_out_buffer *buffer;
enum iucv_tx_notify notification;
+ struct qeth_qdio_out_q *queue;
unsigned int i;

aob = (struct qaob *) phys_to_virt(phys_aob_addr);
@@ -511,7 +512,9 @@ static void qeth_qdio_handle_aob(struct qeth_card *card,
kmem_cache_free(qeth_core_header_cache, data);
}

+ queue = buffer->q;
atomic_set(&buffer->state, QETH_QDIO_BUF_EMPTY);
+ napi_schedule(&queue->napi);
break;
default:
WARN_ON_ONCE(1);
@@ -7013,9 +7016,7 @@ int qeth_open(struct net_device *dev)
card->data.state = CH_STATE_UP;
netif_tx_start_all_queues(dev);

- napi_enable(&card->napi);
local_bh_disable();
- napi_schedule(&card->napi);
if (IS_IQD(card)) {
struct qeth_qdio_out_q *queue;
unsigned int i;
@@ -7027,8 +7028,12 @@ int qeth_open(struct net_device *dev)
napi_schedule(&queue->napi);
}
}
+
+ napi_enable(&card->napi);
+ napi_schedule(&card->napi);
/* kick-start the NAPI softirq: */
local_bh_enable();
+
return 0;
}
EXPORT_SYMBOL_GPL(qeth_open);
@@ -7038,6 +7043,11 @@ int qeth_stop(struct net_device *dev)
struct qeth_card *card = dev->ml_priv;

QETH_CARD_TEXT(card, 4, "qethstop");
+
+ napi_disable(&card->napi);
+ cancel_delayed_work_sync(&card->buffer_reclaim_work);
+ qdio_stop_irq(CARD_DDEV(card));
+
if (IS_IQD(card)) {
struct qeth_qdio_out_q *queue;
unsigned int i;
@@ -7058,10 +7068,6 @@ int qeth_stop(struct net_device *dev)
netif_tx_disable(dev);
}

- napi_disable(&card->napi);
- cancel_delayed_work_sync(&card->buffer_reclaim_work);
- qdio_stop_irq(CARD_DDEV(card));
-
return 0;
}
EXPORT_SYMBOL_GPL(qeth_stop);
--
2.30.1