Re: [PATCH] virtio_bt: Fix alignment in configuration struct

From: "Michael S. Tsirkin" <mst@redhat.com>
To: Igor Skalkin <igor.skalkin@opensynergy.com>
Cc: Johan Hedberg <johan.hedberg@gmail.com>,
	linux-kernel@vger.kernel.org,
	virtualization@lists.linux-foundation.org,
	linux-bluetooth@vger.kernel.org,
	Luiz Augusto von Dentz <luiz.dentz@gmail.com>,
	mgo@opensynergy.com, Marcel Holtmann <marcel@holtmann.org>
Subject: Re: [PATCH] virtio_bt: Fix alignment in configuration struct
Date: Thu, 11 Aug 2022 04:00:02 -0400	[thread overview]
Message-ID: <20220811035817-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20220808081054-mutt-send-email-mst@kernel.org>

On Mon, Aug 08, 2022 at 08:16:11AM -0400, Michael S. Tsirkin wrote:
> On Mon, Aug 08, 2022 at 02:04:43PM +0200, Igor Skalkin wrote:
> > On 8/8/22 01:00, Michael S. Tsirkin wrote:
> > 
> >     On Mon, Aug 08, 2022 at 12:11:52AM +0200, Igor Skalkin wrote:
> > 
> >         According to specification [1], "For the device-specific configuration
> >         space, the driver MUST use 8 bit wide accesses for 8 bit wide fields,
> >         16 bit wide and aligned accesses for 16 bit wide fields and 32 bit wide
> >         and aligned accesses for 32 and 64 bit wide fields.".
> > 
> >         Current version of the configuration structure:
> > 
> >             struct virtio_bt_config {
> >                 __u8  type;
> >                 __u16 vendor;
> >                 __u16 msft_opcode;
> >             } __attribute__((packed));
> > 
> >         has both 16bit fields non-aligned.
> > 
> >         This commit fixes it.
> > 
> >         [1] https://ddec1-0-en-ctp.trendmicro.com:443/wis/clicktime/v1/query?url=https%3a%2f%2fdocs.oasis%2dopen.org%2fvirtio%2fvirtio%2fv1.1%2fvirtio%2dv1.1.pdf&umid=d1786ace-e8ea-40e8-9665-96c0949174e5&auth=53c7c7de28b92dfd96e93d9dd61a23e634d2fbec-39b15885ceebe9fda9357320aec1ccbac416a470
> > 
> >         Signed-off-by: Igor Skalkin <Igor.Skalkin@opensynergy.com>
> > 
> >     This is all true enough, but the problem is
> >     1. changing uapi like this can't be done, will break userspace
> >     2. the driver has more issues and no one seems to want to
> >        maintain it.
> >     I posted a patch "Bluetooth: virtio_bt: mark broken" and intend
> >     to merge it for this release.
> > 
> > This is very sad. We already use this driver in our projects.
> 
> Really?  Can you step up to maintain it? Then we can fix the issues
> and it won't be broken.

Just a reminder that I'm waiting for a response on that.
I just don't know enough about bluetooth.

-- 
MST

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