linux-kernel - Re: [PATCH v1 3/3] usb: dwc3: gadget: Make gadget

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <468898dd-8b57-4fb5-bef1-d47ffbc38846@oss.qualcomm.com>
Date: Wed, 9 Apr 2025 09:45:00 +0530
From: Prashanth K <prashanth.k@....qualcomm.com>
To: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Kees Bakker <kees@...erbout.nl>,
        William McVicker <willmcvicker@...gle.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...nel.org" <stable@...nel.org>
Subject: Re: [PATCH v1 3/3] usb: dwc3: gadget: Make gadget_wakeup asynchronous



On 09-04-25 06:13 am, Thinh Nguyen wrote:
> On Tue, Apr 08, 2025, Prashanth K wrote:
>>
>>
>> On 08-04-25 05:08 am, Thinh Nguyen wrote:
>>> On Thu, Apr 03, 2025, Prashanth K wrote:
> 
>>>> @@ -4398,6 +4371,21 @@ static void dwc3_gadget_linksts_change_interrupt(struct dwc3 *dwc,
>>>>  	}
>>>>  
>>>>  	dwc->link_state = next;
>>>> +
>>>> +	/* Proceed with func wakeup if any interfaces that has requested */
>>>> +	while (dwc->func_wakeup_pending && (next == DWC3_LINK_STATE_U0)) {
>>>> +		if (dwc->func_wakeup_pending & BIT(0)) {
>>>> +			ret = dwc3_send_gadget_generic_command(dwc, DWC3_DGCMD_DEV_NOTIFICATION,
>>>> +							       DWC3_DGCMDPAR_DN_FUNC_WAKE |
>>>> +							       DWC3_DGCMDPAR_INTF_SEL(intf_id));
>>>> +			if (ret)
>>>> +				dev_err(dwc->dev, "function remote wakeup failed for %d, ret:%d\n",
>>>> +					intf_id, ret);
>>>> +		}
>>>> +		dwc->func_wakeup_pending >>= 1;
>>>
>>> This would break the bitmap of dwc->func_wakeup_pending. Perhaps we can
>>> use ffs(x) to properly find and clear the interface ID from the bitmap
>>> one at a time.
>>>
>> Yes, we can use ffs(x). But I didn't understand how this would break
>> bitmap of dwc->func_wakeup_pending.
>>
> 
> Since you're sending device notification to all the wakeup armed
> interfaces and not reusing the func_wakeup_pending afterward, the result
> of what you're doing here will be the same.
> 
> IMHO, for clarity, what I was suggesting is to revise the logic to
> preserve the dwc->func_wakeup_pending bitmap instead of shifting and
> overwriting it, causing the bitmap to no longer match the intf_id. We
> get the intf_id from the bitmap and clear the intf_id bit from the
> bitmap as we go.
> 
The above logic works, but as you suggested I'll refactor it using
ffs(x) and clear the intf_id directly (instead of shifting).

Does this look good?

/* Proceed with func wakeup if any interfaces that has requested */
while (dwc->func_wakeup_pending && (next == DWC3_LINK_STATE_U0)) {
	intf_id = ffs(dwc->func_wakeup_pending);
	if (intf_id)
		ret = dwc3_send_gadget_generic_command(dwc, DWC3_DGCMD_DEV_NOTIFICATION,
							   DWC3_DGCMDPAR_DN_FUNC_WAKE |
							   DWC3_DGCMDPAR_INTF_SEL(intf_id - 1));
		if (ret)
			dev_err(dwc->dev, "function remote wakeup failed for %d, ret:%d\n",
				intf_id, ret);
	}
	dwc->func_wakeup_pending &= ~(1 << (intf_id - 1));
}

Regards,
Prashanth K