[PATCH 4.9 040/212] net: ethernet: ravb: exit if re-initialization fails in tx timeout

From: Greg Kroah-Hartman
Date: Thu Aug 20 2020 - 05:59:25 EST


From: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>

[ Upstream commit 015c5d5e6aa3523c758a70eb87b291cece2dbbb4 ]

According to the report of [1], this driver is possible to cause
the following error in ravb_tx_timeout_work().

ravb e6800000.ethernet ethernet: failed to switch device to config mode

This error means that the hardware could not change the state
from "Operation" to "Configuration" while some tx and/or rx queue
are operating. After that, ravb_config() in ravb_dmac_init() will fail,
and then any descriptors will be not allocaled anymore so that NULL
pointer dereference happens after that on ravb_start_xmit().

To fix the issue, the ravb_tx_timeout_work() should check
the return values of ravb_stop_dma() and ravb_dmac_init().
If ravb_stop_dma() fails, ravb_tx_timeout_work() re-enables TX and RX
and just exits. If ravb_dmac_init() fails, just exits.

[1]
https://lore.kernel.org/linux-renesas-soc/20200518045452.2390-1-dirk.behme@xxxxxxxxxxxx/

Reported-by: Dirk Behme <dirk.behme@xxxxxxxxxxxx>
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
Reviewed-by: Sergei Shtylyov <sergei.shtylyov@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/net/ethernet/renesas/ravb_main.c | 26 ++++++++++++++++++++++--
1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
index 545cb6262cffd..93d3152752ff4 100644
--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c
@@ -1444,6 +1444,7 @@ static void ravb_tx_timeout_work(struct work_struct *work)
struct ravb_private *priv = container_of(work, struct ravb_private,
work);
struct net_device *ndev = priv->ndev;
+ int error;

netif_tx_stop_all_queues(ndev);

@@ -1452,15 +1453,36 @@ static void ravb_tx_timeout_work(struct work_struct *work)
ravb_ptp_stop(ndev);

/* Wait for DMA stopping */
- ravb_stop_dma(ndev);
+ if (ravb_stop_dma(ndev)) {
+ /* If ravb_stop_dma() fails, the hardware is still operating
+ * for TX and/or RX. So, this should not call the following
+ * functions because ravb_dmac_init() is possible to fail too.
+ * Also, this should not retry ravb_stop_dma() again and again
+ * here because it's possible to wait forever. So, this just
+ * re-enables the TX and RX and skip the following
+ * re-initialization procedure.
+ */
+ ravb_rcv_snd_enable(ndev);
+ goto out;
+ }

ravb_ring_free(ndev, RAVB_BE);
ravb_ring_free(ndev, RAVB_NC);

/* Device init */
- ravb_dmac_init(ndev);
+ error = ravb_dmac_init(ndev);
+ if (error) {
+ /* If ravb_dmac_init() fails, descriptors are freed. So, this
+ * should return here to avoid re-enabling the TX and RX in
+ * ravb_emac_init().
+ */
+ netdev_err(ndev, "%s: ravb_dmac_init() failed, error %d\n",
+ __func__, error);
+ return;
+ }
ravb_emac_init(ndev);

+out:
/* Initialise PTP Clock driver */
if (priv->chip_id == RCAR_GEN2)
ravb_ptp_init(ndev, priv->pdev);
--
2.25.1