From: Julian Wiedmann jwi@linux.ibm.com
[ Upstream commit a702349a4099cd5a7bab0904689d8e0bf8dcd622 ]
By updating q->used_buffers only _after_ do_QDIO() has completed, there is a potential race against the buffer's TX completion. In the unlikely case that the TX completion path wins, qeth_qdio_output_handler() would decrement the counter before qeth_flush_buffers() even incremented it.
Signed-off-by: Julian Wiedmann jwi@linux.ibm.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- drivers/s390/net/qeth_core_main.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c index 939b5b5e97ef..0a6afd4b283d 100644 --- a/drivers/s390/net/qeth_core_main.c +++ b/drivers/s390/net/qeth_core_main.c @@ -3507,13 +3507,14 @@ static void qeth_flush_buffers(struct qeth_qdio_out_q *queue, int index, qdio_flags = QDIO_FLAG_SYNC_OUTPUT; if (atomic_read(&queue->set_pci_flags_count)) qdio_flags |= QDIO_FLAG_PCI_OUT; + atomic_add(count, &queue->used_buffers); + rc = do_QDIO(CARD_DDEV(queue->card), qdio_flags, queue->queue_no, index, count); if (queue->card->options.performance_stats) queue->card->perf_stats.outbound_do_qdio_time += qeth_get_micros() - queue->card->perf_stats.outbound_do_qdio_start_time; - atomic_add(count, &queue->used_buffers); if (rc) { queue->card->stats.tx_errors += count; /* ignore temporary SIGA errors without busy condition */