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From: Ikjoon Jang <ikjn@chromium.org>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org,
	Chunfeng Yun <chunfeng.yun@mediatek.com>,
	"moderated list:ARM/Mediatek SoC support" 
	<linux-mediatek@lists.infradead.org>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	open list <linux-kernel@vger.kernel.org>,
	"moderated list:ARM/Mediatek SoC support" 
	<linux-arm-kernel@lists.infradead.org>,
	Mathias Nyman <mathias.nyman@intel.com>
Subject: Re: [RFC PATCH] usb: xhci-mtk: handle bandwidth table rollover
Date: Mon, 9 Aug 2021 17:42:05 +0800	[thread overview]
Message-ID: <CAATdQgDSCzZtiDSQk94CYHfSb9Mq28OH7-RdaTZNv3oPrW3nkQ@mail.gmail.com> (raw)
In-Reply-To: <YRDxTodNNqtnpPpn@kroah.com>

On Mon, Aug 9, 2021 at 5:11 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Mon, Aug 09, 2021 at 04:59:29PM +0800, Ikjoon Jang wrote:
> > xhci-mtk has 64 slots for periodic bandwidth calculations and each
> > slot represents byte budgets on a microframe. When an endpoint's
> > allocation sits on the boundary of the table, byte budgets' slot
> > should be rolled over but the current implementation doesn't.
> >
> > This patch applies a 6 bits mask to the microframe index to handle
> > its rollover 64 slots and prevent out-of-bounds array access.
> >
> > Signed-off-by: Ikjoon Jang <ikjn@chromium.org>
> > ---
> >
> >  drivers/usb/host/xhci-mtk-sch.c | 79 +++++++++------------------------
> >  drivers/usb/host/xhci-mtk.h     |  1 +
> >  2 files changed, 23 insertions(+), 57 deletions(-)
>
> Why is this "RFC"?  What needs to be addressed in this change before it
> can be accepted?

sorry, I had to mention why this is RFC:

I simply don't know about the details of the xhci-mtk internals.
It was okay from my tests with mt8173 and I think this will be harmless
as this is "better than before".

But when I removed get_esit_boundary(), I really have no idea why
it was there. I'm wondering if there was another reason of that function
other than just preventing out-of-bounds. Maybe chunfeng can answer this?

Thanks!

>
> thanks,
>
> greg k-h

  reply	other threads:[~2021-08-09  9:42 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-09  8:59 [RFC PATCH] usb: xhci-mtk: handle bandwidth table rollover Ikjoon Jang
2021-08-09  9:11 ` Greg Kroah-Hartman
2021-08-09  9:42   ` Ikjoon Jang [this message]
2021-08-11  9:01     ` Chunfeng Yun (云春峰)
2021-08-12  9:31       ` Ikjoon Jang
2021-08-12 11:49         ` Chunfeng Yun (云春峰)
2021-08-12 13:47           ` Ikjoon Jang
2021-08-18  2:43           ` Ikjoon Jang
2021-08-20  3:37             ` Chunfeng Yun (云春峰)

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