linux-kernel - Re: [PATCH v2 5/5] usb: xhci: Handle USB transaction error on address command

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Message-ID: <5979AAA5.5090601@linux.intel.com>
Date:   Thu, 27 Jul 2017 16:56:05 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Felipe Balbi <felipe.balbi@...ux.intel.com>,
        Mathias Nyman <mathias.nyman@...ux.intel.com>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        zhengjun.xing@...ux.intel.com
Subject: Re: [PATCH v2 5/5] usb: xhci: Handle USB transaction error on address
 command

Hi,

On 07/27/2017 03:55 PM, Felipe Balbi wrote:
> Hi,
>
> Lu Baolu <baolu.lu@...ux.intel.com> writes:
>> Xhci driver handles USB transaction errors on transfer events,
>> but transaction errors are possible on address device command
>> completion events as well.
>>
>> The xHCI specification (section 4.6.5) says: A USB Transaction
>> Error Completion Code for an Address Device Command may be due
>> to a Stall response from a device. Software should issue a Disable
>> Slot Command for the Device Slot then an Enable Slot Command to
>> recover from this error.
>>
>> This patch handles USB transaction errors on address command
>> completion events. The related discussion threads can be found
>> through below links.
>>
>> http://marc.info/?l=linux-usb&m=149362010728921&w=2
>> http://marc.info/?l=linux-usb&m=149252752825755&w=2
>>
>> Suggested-by: Mathias Nyman <mathias.nyman@...ux.intel.com>
>> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
>> ---
>>  drivers/usb/host/xhci.c | 5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
>> index d6b728d..95780f8 100644
>> --- a/drivers/usb/host/xhci.c
>> +++ b/drivers/usb/host/xhci.c
>> @@ -3822,6 +3822,11 @@ static int xhci_setup_device(struct usb_hcd *hcd, struct usb_device *udev,
>>  		break;
>>  	case COMP_USB_TRANSACTION_ERROR:
>>  		dev_warn(&udev->dev, "Device not responding to setup %s.\n", act);
>> +
>> +		ret = xhci_disable_slot(xhci, udev->slot_id);
>> +		if (!ret)
>> +			xhci_alloc_dev(hcd, udev);
> aren't you leaking previously allocated virt_dev ?
>

When disable slot command completes, the command completion handler
will release the previous allocated virt_dev.

Best regards,
Lu Baolu