| From foo@baz Fri Sep 21 09:28:34 CEST 2018 |
| From: Julian Wiedmann <jwi@linux.ibm.com> |
| Date: Thu, 19 Jul 2018 12:43:48 +0200 |
| Subject: s390/qeth: fix race in used-buffer accounting |
| |
| 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> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| drivers/s390/net/qeth_core_main.c | 3 ++- |
| 1 file changed, 2 insertions(+), 1 deletion(-) |
| |
| --- a/drivers/s390/net/qeth_core_main.c |
| +++ b/drivers/s390/net/qeth_core_main.c |
| @@ -3505,13 +3505,14 @@ static void qeth_flush_buffers(struct qe |
| 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 */ |
