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Message-ID: <063D6719AE5E284EB5DD2968C1650D6D45904D@AcuExch.aculab.com>
Date: Mon, 13 Jan 2014 11:52:04 +0000
From: David Laight <David.Laight@...LAB.COM>
To: 'Bjørn Mork' <bjorn@...k.no>
CC: Thomas Kear <thomas@...r.co.nz>,
Ben Hutchings <bhutchings@...arflare.com>,
netdev <netdev@...r.kernel.org>,
"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>
Subject: RE: PROBLEM: usbnet / ax88179_178a: Panic in usb_hcd_map_urb_for_dma
From: Bjørn Mork
> David Laight <David.Laight@...LAB.COM> writes:
>
> > The patch you submitted is wrong.
> > Whoever wrote the sg interface was on crack.
> > The 'last' marker needs moving as well.
>
> I'm afraid I don't understand what you meant by this.
>
> sg_init_table() set the 'last' marker. AFAICS, you don't need to change
> it unless you want to chain lists.
>
> Care to explain with some code?
Just assuming that there will be some code, somewhere, that will try
to process the entire sg list - so won't like the entry with a
NULL pointer and zero length at the end.
If all the places that process the list are given an explicit
number of entries, or don't care about the NULL it doesn't matter.
David
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