[v2] usb: core: handle port status errors in disable_show()

[PATCH v2] usb: core: handle port status errors in disable_show()

Posted by Karl Mehltretter 1 month, 2 weeks ago

usb_hub_port_status() leaves its output arguments untouched when the
status request fails. disable_show() nevertheless uses portstatus, so a
sysfs read may report the wrong port state instead of an error.

Propagate the status request error.

Fixes: f061f43d7418c ("usb: hub: port: add sysfs entry to switch port power")
Assisted-by: Claude:claude-fable-5
Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
---
Changes in v2:
- Simplify error handling (Alan Stern).

v1: https://lore.kernel.org/r/20260808131601.75096-1-kmehltretter@gmail.com/

 drivers/usb/core/port.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/core/port.c b/drivers/usb/core/port.c
index b4452b665f59..6503668f303b 100644
--- a/drivers/usb/core/port.c
+++ b/drivers/usb/core/port.c
@@ -96,8 +96,9 @@ static ssize_t disable_show(struct device *dev,
 		goto out_hdev_lock;
 	}
 
-	usb_hub_port_status(hub, port1, &portstatus, &unused);
-	disabled = !usb_port_is_power_on(hub, portstatus);
+	rc = usb_hub_port_status(hub, port1, &portstatus, &unused);
+	if (rc >= 0)
+		disabled = !usb_port_is_power_on(hub, portstatus);
 
  out_hdev_lock:
 	usb_unlock_device(hdev);
-- 
2.39.5 (Apple Git-154)

Re: [PATCH v2] usb: core: handle port status errors in disable_show()

Posted by Karl Mehltretter 2 weeks, 2 days ago

On Tue, Aug 11, 2026 at 01:04:32AM +0100, Karl Mehltretter wrote:
> usb_hub_port_status() leaves its output arguments untouched when the
> status request fails. disable_show() nevertheless uses portstatus, so a
> sysfs read may report the wrong port state instead of an error.
> 
> Propagate the status request error.
> 
> Fixes: f061f43d7418c ("usb: hub: port: add sysfs entry to switch port power")
> Assisted-by: Claude:claude-fable-5
> Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
> ---
> Changes in v2:
> - Simplify error handling (Alan Stern).
> 
> v1: https://lore.kernel.org/r/20260808131601.75096-1-kmehltretter@gmail.com/

Friendly ping. Alan Stern has given his Acked-by for this v2.

Thanks,
Karl

Re: [PATCH v2] usb: core: handle port status errors in disable_show()

Posted by Alan Stern 1 month, 2 weeks ago

On Tue, Aug 11, 2026 at 01:04:32AM +0200, Karl Mehltretter wrote:
> usb_hub_port_status() leaves its output arguments untouched when the
> status request fails. disable_show() nevertheless uses portstatus, so a
> sysfs read may report the wrong port state instead of an error.
> 
> Propagate the status request error.
> 
> Fixes: f061f43d7418c ("usb: hub: port: add sysfs entry to switch port power")
> Assisted-by: Claude:claude-fable-5
> Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
> ---

Acked-by: Alan Stern <stern@rowland.harvard.edu>

> Changes in v2:
> - Simplify error handling (Alan Stern).
> 
> v1: https://lore.kernel.org/r/20260808131601.75096-1-kmehltretter@gmail.com/
> 
>  drivers/usb/core/port.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/core/port.c b/drivers/usb/core/port.c
> index b4452b665f59..6503668f303b 100644
> --- a/drivers/usb/core/port.c
> +++ b/drivers/usb/core/port.c
> @@ -96,8 +96,9 @@ static ssize_t disable_show(struct device *dev,
>  		goto out_hdev_lock;
>  	}
>  
> -	usb_hub_port_status(hub, port1, &portstatus, &unused);
> -	disabled = !usb_port_is_power_on(hub, portstatus);
> +	rc = usb_hub_port_status(hub, port1, &portstatus, &unused);
> +	if (rc >= 0)
> +		disabled = !usb_port_is_power_on(hub, portstatus);
>  
>   out_hdev_lock:
>  	usb_unlock_device(hdev);
> -- 
> 2.39.5 (Apple Git-154)
>