| Message ID | 20210402102922.8495-1-ikhoronz@cisco.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net] net: octeon: mgmt: fix xmit hang as busy | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Clearly marked for net |
| netdev/subject_prefix | success | Link |
| netdev/cc_maintainers | fail | 1 blamed authors not CCed: paulburton@kernel.org; 5 maintainers not CCed: dingsenjie@yulong.com andrew@lunn.ch apais@linux.microsoft.com alexander.sverdlin@nokia.com paulburton@kernel.org |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 0 this patch: 0 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | fail | ERROR: Remove Gerrit Change-Id's before submitting upstream |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 0 this patch: 0 |
| netdev/header_inline | success | Link |
diff --git a/drivers/net/ethernet/cavium/octeon/octeon_mgmt.c b/drivers/net/ethernet/cavium/octeon/octeon_mgmt.c index ecffebd513be..be1c353b961c 100644 --- a/drivers/net/ethernet/cavium/octeon/octeon_mgmt.c +++ b/drivers/net/ethernet/cavium/octeon/octeon_mgmt.c @@ -1315,6 +1315,10 @@ octeon_mgmt_xmit(struct sk_buff *skb, struct net_device *netdev) spin_unlock_irqrestore(&p->tx_list.lock, flags); + /* Make sure there is no reorder of filling the ring and ringing + * the bell + */ + wmb(); dma_sync_single_for_device(p->dev, p->tx_ring_handle, ring_size_to_bytes(OCTEON_MGMT_TX_RING_SIZE), DMA_BIDIRECTIONAL);
The issue happens only at appropriate circumstances, in my case I faced it only while running crash kernel, when basic kernel worked fine. The code inspection has shown tx_current_fill counter overflow, after one packet or couple packets were sent. That's because tx cleanup tasklet dequeued bunch of not correct packets afterwards when it should only one. As result xmit queue counter becomes more than tx ring size and xmit always returns NETDEV_TX_BUSY. The reason is in some trash got by dma after ringing the bell. The wmb() in correct place solved the issue, so reason likely in removal of mips_swiotlb_ops which had an mb() after most of the operations and the removal of the ops had broken the tx functionality of the driver implicitly. The patch has been tested on Octeon II. Fixes: a999933db9ed ("MIPS: remove mips_swiotlb_ops") Change-Id: I947c359d9451c75a693bc4a3f2958489503fc0ab Signed-off-by: Ivan Khoronzhuk <ikhoronz@cisco.com> --- Based on net/master drivers/net/ethernet/cavium/octeon/octeon_mgmt.c | 4 ++++ 1 file changed, 4 insertions(+)