From: Vitor Soares <vitor.soares@xxxxxxxxxxx>
When the mcp251xfd_start_xmit() function fails, the driver stops
processing messages, and the interrupt routine does not return,
running indefinitely even after killing the running application.
Error messages:
[ 441.298819] mcp251xfd spi2.0 can0: ERROR in mcp251xfd_start_xmit: -16
[ 441.306498] mcp251xfd spi2.0 can0: Transmit Event FIFO buffer not empty. (seq=0x000017c7, tef_tail=0x000017cf, tef_head=0x000017d0, tx_head=0x000017d3).
... and repeat forever.
The issue can be triggered when multiple devices share the same
SPI interface. And there is concurrent access to the bus.
The problem occurs because tx_ring->head increments even if
mcp251xfd_start_xmit() fails. Consequently, the driver skips one
TX package while still expecting a response in
mcp251xfd_handle_tefif_one().
This patch resolves the issue by decreasing tx_ring->head if
mcp251xfd_start_xmit() fails. With the fix, if we attempt to trigger
the issue again, the driver prints an error and discard the message.
Fixes: 55e5b97f003e ("can: mcp25xxfd: add driver for Microchip MCP25xxFD SPI CAN")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Vitor Soares <vitor.soares@xxxxxxxxxxx>
---
drivers/net/can/spi/mcp251xfd/mcp251xfd-tx.c | 27 ++++++++++----------
1 file changed, 14 insertions(+), 13 deletions(-)
diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd-tx.c b/drivers/net/can/spi/mcp251xfd/mcp251xfd-tx.c
index 160528d3cc26..a8eb941c1b95 100644
--- a/drivers/net/can/spi/mcp251xfd/mcp251xfd-tx.c
+++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd-tx.c
@@ -181,25 +181,26 @@ netdev_tx_t mcp251xfd_start_xmit(struct sk_buff *skb,
tx_obj = mcp251xfd_get_tx_obj_next(tx_ring);
mcp251xfd_tx_obj_from_skb(priv, tx_obj, skb, tx_ring->head);
- /* Stop queue if we occupy the complete TX FIFO */
tx_head = mcp251xfd_get_tx_head(tx_ring);
- tx_ring->head++;
- if (mcp251xfd_get_tx_free(tx_ring) == 0)
- netif_stop_queue(ndev);
-
frame_len = can_skb_get_frame_len(skb);
- err = can_put_echo_skb(skb, ndev, tx_head, frame_len);
- if (!err)
- netdev_sent_queue(priv->ndev, frame_len);
+ can_put_echo_skb(skb, ndev, tx_head, frame_len);
+
+ tx_ring->head++;
err = mcp251xfd_tx_obj_write(priv, tx_obj);
- if (err)
- goto out_err;
+ if (err) {
+ can_free_echo_skb(ndev, tx_head, NULL);
- return NETDEV_TX_OK;
+ tx_ring->head--;
+
+ netdev_err(priv->ndev, "ERROR in %s: %d\n", __func__, err);
+ } else {
+ /* Stop queue if we occupy the complete TX FIFO */
+ if (mcp251xfd_get_tx_free(tx_ring) == 0)
+ netif_stop_queue(ndev);
- out_err:
- netdev_err(priv->ndev, "ERROR in %s: %d\n", __func__, err);
+ netdev_sent_queue(priv->ndev, frame_len);
+ }
return NETDEV_TX_OK;
}
--
2.34.1
