From: "Michał Pecio" <michal.pecio@gmail.com>
To: Mathias Nyman <mathias.nyman@linux.intel.com>
Cc: Mathias Nyman <mathias.nyman@intel.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
Niklas Neronin <niklas.neronin@linux.intel.com>
Subject: Re: [PATCH 1/3] usb: xhci: Simplify update_ring_for_set_deq_completion()
Date: Wed, 5 Mar 2025 09:24:11 +0100 [thread overview]
Message-ID: <20250305092411.6962ca52@foxbook> (raw)
In-Reply-To: <e3ca349d-c77d-4643-9865-f9991b34540f@linux.intel.com>
On Fri, 21 Feb 2025 15:23:11 +0200, Mathias Nyman wrote:
> update_ring_for_set_deq_completion() isn't needed anymore.
> Niklas already wrote a patch to remove it.
>
> It's sitting in my for-usb-next branch
>
> https://git.kernel.org/pub/scm/linux/kernel/git/mnyman/xhci.git/commit/?h=for-usb-next&id=ee7dab196a7dfc48a1608274329323cb10b4340d
I know that it's pure paranoia, but this patch removes a quiet debug
message about an obviously abnormal and likely harmful condition.
My patch turned it into a nice red error.
This will be something to keep in mind, for example somebody could
write a patch which reclaims an empty transfer ring segment without
chceking if there is a Set TR Dequeue pending to this segemnt. That
could lead to very interesting outcomes if all TRBs in the segment
are No-Op'ed and the next page is a transfer ring of other endpoint.
Other than that, I suppose there is currently no problem. The loop
for finding new dequeue position doesn't seem prone to jumping off
the ring as long as the ring itself isn't corrupted.
Michal
next prev parent reply other threads:[~2025-03-05 8:24 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-20 22:43 [PATCH 0/3] xhci: ring queuing cleanups Michal Pecio
2025-02-20 22:44 ` [PATCH 1/3] usb: xhci: Simplify update_ring_for_set_deq_completion() Michal Pecio
2025-02-21 13:23 ` Mathias Nyman
2025-03-05 8:24 ` Michał Pecio [this message]
2025-02-20 22:46 ` [PATCH 2/3] usb: xhci: Simplify moving HW Dequeue Pointer past cancelled TDs Michal Pecio
2025-02-20 22:47 ` [PATCH 3/3] usb: xhci: Unify duplicate inc_enq() code Michal Pecio
2025-02-21 14:54 ` Mathias Nyman
2025-02-23 23:45 ` Michał Pecio
2025-02-24 11:49 ` Mathias Nyman
2025-02-24 21:01 ` Michał Pecio
2025-02-25 9:33 ` Mathias Nyman
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