[PATCH] usb: xhci: return an error if the host is not halted

[PATCH] usb: xhci: return an error if the host is not halted

[Henry Tseng]

xhci_reset() returns 0 when the host is not halted, without ever writing
CMD_RESET. Every other path that fails to reset the host returns an
error, so callers that check the return value are told the reset
succeeded on the one path where it did not happen.

Return -EBUSY when the reset is aborted because the host is not halted.

Signed-off-by: Henry Tseng <henrytseng@qnap.com>
---
 drivers/usb/host/xhci.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index a9e47e178c28..2af6a7b91e55 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -195,7 +195,7 @@ int xhci_reset(struct xhci_hcd *xhci, u64 timeout_us)
 
 	if ((state & STS_HALT) == 0) {
 		xhci_warn(xhci, "Host controller not halted, aborting reset.\n");
-		return 0;
+		return -EBUSY;
 	}
 
 	xhci_dbg_trace(xhci, trace_xhci_dbg_init, "// Reset the HC");
-- 
2.43.0

Re: [PATCH] usb: xhci: return an error if the host is not halted

[Michal Pecio]

On Wed,  2 Sep 2026 18:15:10 +0800, Henry Tseng wrote:
> xhci_reset() returns 0 when the host is not halted, without ever writing
> CMD_RESET. Every other path that fails to reset the host returns an
> error, so callers that check the return value are told the reset
> succeeded on the one path where it did not happen.
> 
> Return -EBUSY when the reset is aborted because the host is not halted.
> 
> Signed-off-by: Henry Tseng <henrytseng@qnap.com>
> ---
>  drivers/usb/host/xhci.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
> index a9e47e178c28..2af6a7b91e55 100644
> --- a/drivers/usb/host/xhci.c
> +++ b/drivers/usb/host/xhci.c
> @@ -195,7 +195,7 @@ int xhci_reset(struct xhci_hcd *xhci, u64 timeout_us)
>  
>  	if ((state & STS_HALT) == 0) {
>  		xhci_warn(xhci, "Host controller not halted, aborting reset.\n");
> -		return 0;
> +		return -EBUSY;

That's probably how it should be, but I wonder how did you find this
bug and are you aware of any cases where it makes a difference?

There is apparently one caller (xhci_resume()) which cares about
xhci_reset() return value but not about the preceding xhci_halt().
 
>  	}
>  
>  	xhci_dbg_trace(xhci, trace_xhci_dbg_init, "// Reset the HC");
> -- 
> 2.43.0
>