linux-kernel - Re: [PATCH v2 1/5] usb: xhci: Disable slot even virt-dev is null

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Message-ID: <598D05D2.7040403@linux.intel.com>
Date:   Fri, 11 Aug 2017 09:18:10 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Mathias Nyman <mathias.nyman@...ux.intel.com>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        zhengjun.xing@...ux.intel.com,
        Guoqing Zhang <guoqing.zhang@...el.com>
Subject: Re: [PATCH v2 1/5] usb: xhci: Disable slot even virt-dev is null

Hi,

On 08/10/2017 06:00 PM, Mathias Nyman wrote:
> On 10.08.2017 03:35, Lu Baolu wrote:
>> Hi,
>>
>> On 08/09/2017 03:58 PM, Mathias Nyman wrote:
>>> On 27.07.2017 05:21, Lu Baolu wrote:
>>>> xhci_disable_slot() is a helper for disabling a slot when a device
>>>> goes away or recovers from error situations. Currently, it checks
>>>> the corespoding virt-dev pointer and returns directly (w/o issuing
>>>> disable slot command) if it's null.
>>>>
>>>> This is unnecessary and will cause problems in case where virt-dev
>>>> allocation fails and xhci_disable_slot() is called to roll back the
>>>> hardware state. Refer to the implementation of xhci_alloc_dev().
>>>>
>>>
>>> True, checking for xhci->devs[slot_id] doesn't work if xhci_alloc_dev()
>>> failed xhci_alloc_virt_device() and calls xhci_disable_slot,
>>>
>>> but the virt dev check is needed for test mode, which will just try
>>> to disable all slots from 1 to HCS_MAX_SLOTS:
>>>
>>>   xhci_enter_test_mode(..)
>>>         /* Disable all Device Slots */
>>>      for (i = 1; i <= HCS_MAX_SLOTS(xhci->hcs_params1); i++) {
>>>                  retval = xhci_disable_slot(xhci, NULL, i);
>>>
>>>
>>
>> So, how about checking virt dev before this invoking?
>>
>> @@ -612,10 +612,12 @@ static int xhci_enter_test_mode(struct xhci_hcd *xhci,
>>          xhci_dbg(xhci, "Disable all slots\n");
>>          spin_unlock_irqrestore(&xhci->lock, *flags);
>>          for (i = 1; i <= HCS_MAX_SLOTS(xhci->hcs_params1); i++) {
>> -               retval = xhci_disable_slot(xhci, NULL, i);
>> -               if (retval)
>> -                       xhci_err(xhci, "Failed to disable slot %d, %d. Enter test mode anyway\n",
>> -                                i, retval);
>> +               if (xhci->devs[i]) {
>> +                       retval = xhci_disable_slot(xhci, NULL, i);
>> +                       if (retval)
>> +                               xhci_err(xhci, "Failed to disable slot %d, %d. Enter test mode anyway\n",
>> +                                        i, retval);
>> +               }
>
>
> Yes, something like this will work
>

Okay, I will submit a v3 to include this change.

Best regards,
Lu Baolu