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

From: Michał Pecio
Date: Sun Jul 14 2024 - 11:32:56 EST


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".

Regards,
Michal