linux-kernel - Re: [PATCH 5/5] usb: xhci: Skip only one TD on Ring Underrun/Overrun

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: <20250221021712.48c07fe0@foxbook>
Date: Fri, 21 Feb 2025 02:17:12 +0100
From: Michał Pecio <michal.pecio@...il.com>
To: Mathias Nyman <mathias.nyman@...ux.intel.com>
Cc: Mathias Nyman <mathias.nyman@...el.com>, Greg Kroah-Hartman
 <gregkh@...uxfoundation.org>, Niklas Neronin
 <niklas.neronin@...ux.intel.com>, linux-usb@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/5] usb: xhci: Skip only one TD on Ring
 Underrun/Overrun

On Tue, 11 Feb 2025 17:41:39 +0200, Mathias Nyman wrote:
> On 10.2.2025 9.42, Michal Pecio wrote:
> > +				if (ring_xrun_event) {
> > +					/*
> > +					 * If we are here, we are on xHCI 1.0 host with no idea how
> > +					 * many TDs were missed and where the xrun occurred. Don't
> > +					 * skip more TDs, they may have been queued after the xrun.
> > +					 */
> > +					xhci_dbg(xhci, "Skipped one TD for slot %u ep %u",
> > +							slot_id, ep_index);
> > +					break;  
> 
> This would be the same as return 0; right?
> 
> Whole series looks good, I'll add it

I hope you haven't sent it out yet because I found two minor issues.

Firstly,
[PATCH 3/5] usb: xhci: Fix isochronous Ring Underrun/Overrun event handling

increases the number of xrun events that we handle but doesn't suppress
the "Event TRB for slot %u ep %u with no TDs queued\n" warning, so the
warning started to show up sometimes for no good reason. The fix is to
add ring_xrun_event to the list of exception for this warning.

Secondly,
[PATCH 5/5] usb: xhci: Skip only one TD on Ring Underrun/Overrun

can be improved to clear the skip flag if skipped TD was the only one.
This eliminates any confusion and risk of skipping bugs in the future.
The change is a matter of moving that code to a different branch.

I also changed 'break' to 'return 0' because it gets hard to follow at
this level of indentation.

I'll send a v2 of those two patches. Sorry for any inconvenience.

Michal