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Subject: Re: [RFT PATCH] xhci: Fix memory leak when caching protocol extended
 capability PSI tables
To:     Greg KH <gregkh@linuxfoundation.org>
Cc:     pmenzel@molgen.mpg.de, mika.westerberg@linux.intel.com,
        linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
References: <572bea6f-06d4-938a-802e-93386acf59d9@linux.intel.com>
 <20200108151730.21022-1-mathias.nyman@linux.intel.com>
 <20200108154008.GA2448418@kroah.com>
From:   Mathias Nyman <mathias.nyman@linux.intel.com>
Message-ID: <9e91c6a7-94a5-6ed7-22c7-ebc956403e8f@linux.intel.com>
Date:   Wed, 8 Jan 2020 17:56:50 +0200
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On 8.1.2020 17.40, Greg KH wrote:
> On Wed, Jan 08, 2020 at 05:17:30PM +0200, Mathias Nyman wrote:
>> xhci driver assumed that xHC controllers have at most one custom
>> supported speed table (PSI) for all usb 3.x ports.
>> Memory was allocated for one PSI table under the xhci hub structure.
>>
>> Turns out this is not the case, some controllers have a separate
>> "supported protocol capability" entry with a PSI table for each port.
>> This means each usb3 port can in theory support different custom speeds.
> 
> Is there a "max" number of port capabilities that can happen?  Or this
> this truely dynamic?

Almost truly dynamic, each capability points to the next, last points to 0

But we can't have more "supported protocol capabilities" than xHC ports.
(MaxPorts value in xHC HCSPARAMS1 register)

> 
>> +	for (i = 0; i < xhci->num_port_caps; i++) {
>> +		kfree(xhci->port_caps[i].psi);
>> +		xhci->port_caps[i].psi = NULL;
>> +	}
> 
> Nit, no need to set to NULL here :)

Thanks, will remove that

-Mathias