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net: ethernet: ravb: exit if re-initialization fails in tx timeout 

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@de.bosch.com/

Reported-by: Dirk Behme <dirk.behme@de.bosch.com>
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Sergei Shtylyov <sergei.shtylyov@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Yoshihiro Shimoda 2020-07-21 15:23:12 +09:00 committed by David S. Miller
parent ca67323552
commit 015c5d5e6a
1 changed files with 24 additions and 2 deletions
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26
drivers/net/ethernet/renesas/ravb_main.c
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@ -1450,6 +1450,7 @@ 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);
@ -1458,15 +1459,36 @@ 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);