Re: [PATCH 6.1 000/102] 6.1.98-rc1 review

[Salvatore Bonaccorso <carnil@debian.org>]

Hi,

On Sun, Jul 14, 2024 at 05:32:39PM +0200, Michał Pecio wrote:
> This looks like bug 219039, please see if my suggested solution works.
> 
> The upstream commit is correct, because the call to inc_deq() has been
> moved outside handle_tx_event() so there is no longer this critical
> difference between doing 'goto cleanup' and 'return 0'. The intended
> change of this commit also makes sense to me.
> 
> This refactor is already present in v6.9 so I don't think the commit
> will have any effect besides fixing the isochronous bug which it is
> meant to fix.
> 
> But it is not present in v6.6 and v6.1, so they break/crash/hang/etc.
> Symptoms may vary, but I believe the root cause is the same because the
> code is visibly wrong.
> 
> 
> I would like to use this opportunity to point out that the xhci driver
> is currenty undergoing (much needed IMO) cleanups and refactors and
> this is not the first time when a naive, verbatim backport is attempted
> of a patch which works fine on upstream, but causes problems on earlier
> kernels. These things need special scrutiny, beyond just "CC:stable".

For tracking I guess this should go as well to the regressions list?

#regzbot introduced: 948554f1bb16e15b90006c109c3a558c66d4c4ac
#regzbot title: freezes on plugging USB connector due to 948554f1bb16 ("usb: xhci: prevent potential failure in handle_tx_event() for Transfer events without TRB")
#regzbot monitor: https://bugzilla.kernel.org/show_bug.cgi?id=219039

Thorsten I hope I got the most bits correctly, how would one inform
regzbot about the regresssion for 6.1.98 and 6.6.39 but not happening
in the upper versions?

Regards,
Salvatore