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From: David Laight <David.Laight@ACULAB.COM>
To: 'Chen Gang S' <gang.chen@sunrus.com.cn>, Marcel Holtmann
	<marcel@holtmann.org>
CC: Joe Perches <joe@perches.com>, Sergei Shtylyov
	<sergei.shtylyov@cogentembedded.com>, "Gustavo F. Padovan"
	<gustavo@padovan.org>, Johan Hedberg <johan.hedberg@gmail.com>, "David S.
 Miller" <davem@davemloft.net>, "linux-bluetooth@vger.kernel.org"
	<linux-bluetooth@vger.kernel.org>, "linux-kernel@vger.kernel.org"
	<linux-kernel@vger.kernel.org>, "netdev@vger.kernel.org"
	<netdev@vger.kernel.org>
Subject: RE: [PATCH v3] net: bluetooth: hci_sock: Use 'const u32 *' instead
 of 'void *' for 2nd parameter of hci_test_bit()
Date: Mon, 9 Feb 2015 10:44:44 +0000
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From: Chen Gang
...
> So at present, in kernel part, we can only say the original authors
> intended to do like this. And only within kernel part, it can not cause
> issue. I guess, original authors originally knew what we talk about.

I've just searched for hci_u*filter it is all horrid.
Look at the code for get/set_sockopt of HCI_FILTER.
Someone seems to have done a complete 'bodge job' of fixing the user interf=
ace
for apps (32bit and 64bit) on 64bit kernels.

> This patch is for fixing building warnings without any negative effect.
> And most of us are not the suitable members to continue analyzing. So
> at present, for me, we can accept this patch.

And, not uncommonly, it has shown up a 'bag of worms'.

If you change 'hci_filter' to contain u32[2] then you can drop
all of the casts and the temporary structures in the sockopt code.
Just be aware of the tail-padding.

	David