linux-kernel - Re: [PATCH 2/5] usb: xhci: Clean up the TD skipping loop

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Message-ID: <20250224010245.75ba1d2f@foxbook>
Date: Mon, 24 Feb 2025 01:02:45 +0100
From: Michał Pecio <michal.pecio@...il.com>
To: "Neronin, Niklas" <niklas.neronin@...ux.intel.com>
Cc: Mathias Nyman <mathias.nyman@...el.com>, Greg Kroah-Hartman
 <gregkh@...uxfoundation.org>, linux-usb@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/5] usb: xhci: Clean up the TD skipping loop

On Sat, 22 Feb 2025 14:37:58 +0200, Neronin, Niklas wrote:
> This debug message is now misleading, the TD way or may not be found
> on non-isochronous.
> 
> Before:
> 	if (ep_seg && ep->skip)
> 		xhci_dbg(xhci, "Found td. ...
> After:
> 	if (ep->skip && (ep_seg || !isoc))
> 		xhci_dbg(xhci, "Found td. ...

Hmm, you're right, the whole block will now execute in this
pathological edge case and we will clear the flag too.

It can be fixed quite easily, but I think I may actually drop this
patch altogether. It will make the next patch slightly more verbose
(that's why I included this one), but it will also make it possible
to backport any of those patches to 6.12-lts if a need arises.

I also realized that one more skipping pathology is a recent (6.11)
regression and perhaps it too could be fixed without major rework,
basically by going back to something similar to pre-6.11 behavior.

I should have v3 ready in a day or a few.

Regards,
Michal