Re: [Intel-wired-lan] [PATCH 1/5] idpf: skip getting/setting ring params if vport is NULL during HW reset

On Tue, Jan 6, 2026 at 9:30 PM Paul Menzel [off-list ref] wrote:

Dear Li,


Thank you for your patch.

Am 07.01.26 um 02:04 schrieb Li Li via Intel-wired-lan:

quoted

When an idpf HW reset is triggered, it clears the vport but does
not clear the netdev held by vport:

     // In idpf_vport_dealloc() called by idpf_init_hard_reset(),
     // idpf_init_hard_reset() sets IDPF_HR_RESET_IN_PROG, so
     // idpf_decfg_netdev() doesn't get called.

No need to format this as code comments. At least it confused me a little.

Thanks for the pointer. Will drop the comment format in the future.

quoted

     if (!test_bit(IDPF_HR_RESET_IN_PROG, adapter->flags))
         idpf_decfg_netdev(vport);
     // idpf_decfg_netdev() would clear netdev but it isn't called:
     unregister_netdev(vport->netdev);
     free_netdev(vport->netdev);
     vport->netdev = NULL;
     // Later in idpf_init_hard_reset(), the vport is cleared:
     kfree(adapter->vports);
     adapter->vports = NULL;

During an idpf HW reset, when "ethtool -g/-G" is called on the netdev,
the vport associated with the netdev is NULL, and so a kernel panic
would happen:

[  513.185327] BUG: kernel NULL pointer dereference, address: 0000000000000038
...
[  513.232756] RIP: 0010:idpf_get_ringparam+0x45/0x80

This can be reproduced reliably by injecting a TX timeout to cause
an idpf HW reset, and injecting a virtchnl error to cause the HW
reset to fail and retry, while calling "ethtool -g/-G" on the netdev
at the same time.

If you shared the commands, how to do that, it would make reproducing
the issue easier.

Here's what I did to introduce TX timeouts and virtchnl timeouts at run time:

--- a/drivers/net/ethernet/intel/idpf/idpf_txrx.c
+++ b/drivers/net/ethernet/intel/idpf/idpf_txrx.c

@@ -15,6 +15,9 @@ struct idpf_tx_stash {
 #define idpf_tx_buf_compl_tag(buf)     (*(u32 *)&(buf)->priv)
 LIBETH_SQE_CHECK_PRIV(u32);

+static bool SIMULATE_TX_TIMEOUT;
+module_param(SIMULATE_TX_TIMEOUT, bool, 0644);
+
 /**
  * idpf_chk_linearize - Check if skb exceeds max descriptors per packet
  * @skb: send buffer

@@ -79,6 +82,8 @@ void idpf_tx_timeout(struct net_device *netdev,

unsigned int txqueue)

        adapter->tx_timeout_count++;

+       SIMULATE_TX_TIMEOUT = false;
+
        netdev_err(netdev, "Detected Tx timeout: Count %d, Queue %d\n",
                   adapter->tx_timeout_count, txqueue);
        if (!idpf_is_reset_in_prog(adapter)) {

@@ -2028,6 +2033,12 @@ static bool idpf_tx_clean_complq(struct

idpf_compl_queue *complq, int budget,
                }
                tx_q = complq->txq_grp->txqs[rel_tx_qid];

+               if (unlikely(SIMULATE_TX_TIMEOUT && (tx_q->idx == 1))) {
+                       netdev_err(tx_q->netdev, "boolli test:
triggering TX timeout for TX queue id %d\n", tx_q->idx);
+                       goto fetch_next_desc;
+               }
+
+
                /* Determine completion type */
                ctype = le16_get_bits(tx_desc->qid_comptype_gen,
                                      IDPF_TXD_COMPLQ_COMPL_TYPE_M);

--- a/drivers/net/ethernet/intel/idpf/idpf_virtchnl.c
+++ b/drivers/net/ethernet/intel/idpf/idpf_virtchnl.c

@@ -6,6 +6,9 @@
 #include "idpf.h"
 #include "idpf_virtchnl.h"

+static bool SIMULATE_VC_TIMEOUT;
+module_param(SIMULATE_VC_TIMEOUT, bool, 0644);
+
 #define IDPF_VC_XN_MIN_TIMEOUT_MSEC    2000
 #define IDPF_VC_XN_DEFAULT_TIMEOUT_MSEC        (60 * 1000)
 #define IDPF_VC_XN_IDX_M               GENMASK(7, 0)

@@ -800,6 +803,10 @@ static int idpf_send_ver_msg(struct idpf_adapter *adapter)
        xn_params.timeout_ms = IDPF_VC_XN_DEFAULT_TIMEOUT_MSEC;

        reply_sz = idpf_vc_xn_exec(adapter, &xn_params);
+       if (SIMULATE_VC_TIMEOUT) {
+               dev_err(&adapter->pdev->dev, "boolli test: simulating

VC timeout by returning -ETIME in idpf_send_ver_msg");
+               reply_sz = -ETIME;
+       }
        if (reply_sz < 0)
                return reply_sz;
        if (reply_sz < sizeof(vvi))

Then after the kernel is booted, we can introduce the TX timeout that
lasts forever by doing the following:

echo 1 | tee /sys/module/idpf/parameters/SIMULATE_TX_TIMEOUT && echo 1
| tee /sys/module/idpf/parameters/SIMULATE_VC_TIMEOUT

All my experiments in this patch series were performed after the
kernel was put in such a state.

quoted

With this patch applied, we see the following error but no kernel
panics anymore:

[  476.323630] idpf 0000:05:00.0 eth1: failed to get ring params due to no vport in netdev

Signed-off-by: Li Li <redacted>
---
  drivers/net/ethernet/intel/idpf/idpf_ethtool.c | 12 ++++++++++++
  1 file changed, 12 insertions(+)

diff --git a/drivers/net/ethernet/intel/idpf/idpf_ethtool.c b/drivers/net/ethernet/intel/idpf/idpf_ethtool.c
index d5711be0b8e69..6a4b630b786c2 100644
--- a/drivers/net/ethernet/intel/idpf/idpf_ethtool.c
+++ b/drivers/net/ethernet/intel/idpf/idpf_ethtool.c

@@ -639,6 +638,10 @@ static void idpf_get_ringparam(struct net_device *netdev,

      idpf_vport_ctrl_lock(netdev);
      vport = idpf_netdev_to_vport(netdev);
+     if (!vport) {
+             netdev_err(netdev, "failed to get ring params due to no vport in netdev\n");

If vport == NULL is expected, why log it as an error. What should the
user do? Wait until reset is done?

quoted

+             goto unlock;
+     }

      ring->rx_max_pending = IDPF_MAX_RXQ_DESC;
      ring->tx_max_pending = IDPF_MAX_TXQ_DESC;

@@ -647,6 +651,7 @@ static void idpf_get_ringparam(struct net_device *netdev,

      kring->tcp_data_split = idpf_vport_get_hsplit(vport);

+unlock:
      idpf_vport_ctrl_unlock(netdev);
  }

@@ -673,6 +674,11 @@ static int idpf_set_ringparam(struct net_device *netdev,

      idpf_vport_ctrl_lock(netdev);
      vport = idpf_netdev_to_vport(netdev);
+     if (!vport) {
+             netdev_err(netdev, "ring params not changed due to no vport in netdev\n");
+             err = -EFAULT;
+             goto unlock_mutex;
+     }

      idx = vport->idx;

Is there another – possible more involved – solution possible to wait
until the hardware reset finished?

Please see Emil's patch series at
https://lore.kernel.org/intel-wired-lan/20251121001218.4565-1-emil.s.tantilov@intel.com/ (local),
in which https://lore.kernel.org/intel-wired-lan/20251121001218.4565-3-emil.s.tantilov@intel.com/ (local)
detaches the netdev at the start of a HW reset, which I also think is
a more elegant solution than mine.

I'm going to drop this patch series in favor of Emil's solution above.

Kind regards,

Paul