Re: [PATCH v2 7/7] thunderbolt: prevent pcie tunnel activation/teardown warnings

[Mika Westerberg <mika.westerberg@linux.intel.com>]

On Tue, Nov 10, 2026 at 07:48:55PM +0800, Chunfeng Yun wrote:
> When usb4 enter sleep mode, echo 1 to authorized of sysfile,
> will wakeup usb4 driver, but fail to create pcie tunnel, cause
> the warning due to a race condition between router disconnect
> during resume and user authorization

This is hard to understand.

Also PCIe, USB4 and so on.

> 
> [  278.831186] usb4_hi NVDA8100:00: 0:1: is unplugged (state: 7), retrying...
> [  278.943031] usb4_hi NVDA8100:00: 0:1: failed to reach state TB_PORT_UP. Ignoring port...
> [  278.951125] usb4_hi NVDA8100:00: 0:1: lost during suspend, disconnecting
> ...
> [  279.013763] usb4_hi NVDA8100:00: 0:7 <-> 1:9 (PCI): activating
> [  279.019587] usb4_hi NVDA8100:00: activating PCIe Down path from 0:7 to 1:9
> [  279.026468] usb4_hi NVDA8100:00: 1:1: Writing hop 1
> [  279.031335] usb4_hi NVDA8100:00: 1:1:  In HopID: 8 => Out port: 9 Out HopID: 8
> [  279.038546] usb4_hi NVDA8100:00: 1:1:   Weight: 1 Priority: 3 Credits: 32 Drop: 0 PM: 0
> [  279.046536] usb4_hi NVDA8100:00: 1:1:    Counter enabled: 0 Counter index: 2047
> [  279.053834] usb4_hi NVDA8100:00: 1:1:   Flow Control (In/Eg): 1/0 Shared Buffer (In/Eg): 0/0
> [  279.062259] usb4_hi NVDA8100:00: 1:1:   Unknown1: 0x0 Unknown2: 0x0 Unknown3: 0x0
> [  279.069730] ------------[ cut here ]------------
> [  279.074335] usb4_hi NVDA8100:00: PCIe Down path activation failed
> [  279.080426] WARNING: CPU: 5 PID: 2433 at drivers/thunderbolt/path.c:587 tb_path_activate+0x1a4/0x5b0
> ...
> [  279.220285] Call trace:
> [  279.222722]  tb_path_activate+0x1a4/0x5b0 (P)
> [  279.227068]  tb_tunnel_activate+0x140/0x498
> [  279.231241]  tb_tunnel_pci+0x180/0x490
> [  279.234980]  tb_domain_approve_switch+0x74/0xb0
> [  279.239500]  authorized_store+0x214/0x270
> [  279.243498]  dev_attr_store+0x20/0x70
> ...
> [  279.288888] ---[ end trace 0000000000000000 ]---
> [  279.293497] usb4_hi NVDA8100:00: 0:7 <-> 1:9 (PCI): activation failed
> 
> When usb4 enter sleep mode, echo 0 to authorized of sysfile,
> will wakeup usb4 driver, but fail to disconnect pcie due to
> the PCIe tunnel had already been torn down and freed if the port
> is fail to resume,

Please put the steps like:

1) Boot the system, nothing connected.
2) Once booted up, connected device.
3) Authorize PCIe tunnel via echo 1 > ..
...

So that we can see what are the steps you reproduce this. The above is
really hard to follow at least to me.

> 
> [  545.887822] usb4_hi NVDA8100:00: 0:1: is unplugged (state: 7), retrying...
> [  545.998689] usb4_hi NVDA8100:00: 0:1: failed to reach state TB_PORT_UP. Ignoring port...
> [  546.006778] usb4_hi NVDA8100:00: 0:1: lost during suspend, disconnecting
> [  546.013474] usb4_hi NVDA8100:00: 0:4 <-> 1:16 (USB3): deactivating
> [  546.020449] usb4_hi NVDA8100:00: deactivating USB3 Down path from 0:4 to 1:16
> [  546.027959] usb4_hi NVDA8100:00: deactivating USB3 Up path from 1:16 to 0:4
> [  546.035649] usb4_hi NVDA8100:00: 0:7 <-> 1:9 (PCI): deactivating
> [  546.042463] usb4_hi NVDA8100:00: deactivating PCIe Down path from 0:7 to 1:9
> [  546.050320] usb4_hi NVDA8100:00: deactivating PCIe Up path from 1:9 to 0:7
> [  546.057790] usb4_hi NVDA8100:00: 0: TMU: mode change off -> bi-directional, HiFi requested
> [  546.067910] usb4_hi NVDA8100:00: 0: TMU: mode set to: bi-directional, HiFi
> [  546.076120] usb4_hi NVDA8100:00: 0:1: total credits changed 66 -> 66
> [  546.082844] usb4_hi NVDA8100:00: 1: link width set to symmetric, dual lanes
> [  546.089815] ------------[ cut here ]------------
> [  546.094420] WARNING: CPU: 7 PID: 2433 at drivers/thunderbolt/tb.c:2245 tb_disconnect_pci+0x108/0x120
> ...
> [  546.238810] Call trace:
> [  546.241246]  tb_disconnect_pci+0x108/0x120 (P)
> [  546.245680]  tb_domain_disapprove_switch+0x24/0x60
> [  546.250464]  disapprove_switch+0xbc/0xe8
> [  546.254378]  authorized_store+0x19c/0x270
> [  546.258378]  dev_attr_store+0x20/0x70
> ...
> [  546.303767] ---[ end trace 0000000000000000 ]---
> 
> The check prevents a redundant lookup and eliminates the warning
> 
> Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
> ---
> v2: no changes
> ---
>  drivers/thunderbolt/switch.c | 5 +++++
>  drivers/thunderbolt/tb.c     | 7 +++++++
>  2 files changed, 12 insertions(+)
> 
> diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
> index e12546bfb869..6e9f439ebf3f 100644
> --- a/drivers/thunderbolt/switch.c
> +++ b/drivers/thunderbolt/switch.c
> @@ -1850,6 +1850,11 @@ static int tb_switch_set_authorized(struct tb_switch *sw, unsigned int val)
>  	if (!!sw->authorized == !!val)
>  		goto unlock;
>  
> +	if (sw->is_unplugged) {
> +		ret = -ENODEV;
> +		goto unlock;
> +	}
> +
>  	switch (val) {
>  	/* Disapprove switch */
>  	case 0:
> diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c
> index 57c11ba13459..69310622d786 100644
> --- a/drivers/thunderbolt/tb.c
> +++ b/drivers/thunderbolt/tb.c
> @@ -2266,6 +2266,10 @@ static int tb_disconnect_pci(struct tb *tb, struct tb_switch *sw)
>  	struct tb_tunnel *tunnel;
>  	struct tb_port *up;
>  
> +	/* If the switch has already been unplugged, tunnels are already freed */

router

everywhere

> +	if (sw->is_unplugged)
> +		return 0;
> +

Actually I'm thinking that we can just get rid of the WARN_ON()s instead.
If the router is gone we cannot find the upstream port nor the tunnel and
that's fine so just return error instead.

>  	up = tb_switch_find_port(sw, TB_TYPE_PCIE_UP);
>  	if (WARN_ON(!up))
>  		return -ENODEV;
> @@ -2288,6 +2292,9 @@ static int tb_tunnel_pci(struct tb *tb, struct tb_switch *sw)
>  	struct tb_cm *tcm = tb_priv(tb);
>  	struct tb_tunnel *tunnel;
>  
> +	if (sw->is_unplugged)
> +		return -ENODEV;
> +
>  	up = tb_switch_find_port(sw, TB_TYPE_PCIE_UP);
>  	if (!up)
>  		return 0;
> -- 
> 2.45.2