Linux Virtualization - Aug 2014 - [3.16 stable PATCH 1/1] virtio-rng: fix multi-device startup

On (Tue) 12 Aug 2014 [06:55:27], Greg KH wrote:
> On Mon, Aug 11, 2014 at 06:11:47PM +0530, Amit Shah wrote:
> > This is a 3.16-only patch.  The linux.git fix is
> > 5c06273401f2eb7b290cadbae18ee00f8f65e893, which fixes this issue in a
> > different way.
> 
> Why "different"?  Why can't I take that original patch
instead?  What is
> different in this patch, and why?
The commit referenced moves the hwrng_register() call to the ->scan()
callback instead of it being in probe().  This was done to ensure the
virtio-rng devices can contribute to the initial system entropy
introduced in commit d9e7972619334.

That patch is quite small too, but will need a slight conflict
resolution due to the previous two code-shuffling patches, and also
the following revert.

However, I decided against the backport of the ->scan() method, since
it wasn't designed to solve this regression, it happens to solve it,
and it actually introduces new functionality.  I would be happy to
provide a backport of the relevant patches, if you think that would be
alright.

Thanks,

		Amit

On Tue, Aug 12, 2014 at 11:01:58AM +0530, Amit Shah
wrote:
> On (Tue) 12 Aug 2014 [06:55:27], Greg KH wrote:
> > On Mon, Aug 11, 2014 at 06:11:47PM +0530, Amit Shah wrote:
> > > This is a 3.16-only patch.  The linux.git fix is
> > > 5c06273401f2eb7b290cadbae18ee00f8f65e893, which fixes this issue
in a
> > > different way.
> > 
> > Why "different"?  Why can't I take that original patch
instead?  What is
> > different in this patch, and why?
> 
> The commit referenced moves the hwrng_register() call to the ->scan()
> callback instead of it being in probe().  This was done to ensure the
> virtio-rng devices can contribute to the initial system entropy
> introduced in commit d9e7972619334.
> 
> That patch is quite small too, but will need a slight conflict
> resolution due to the previous two code-shuffling patches, and also
> the following revert.
> 
> However, I decided against the backport of the ->scan() method, since
> it wasn't designed to solve this regression, it happens to solve it,
> and it actually introduces new functionality.  I would be happy to
> provide a backport of the relevant patches, if you think that would be
> alright.
I almost always want "original" patches as it causes less bugs
overall,
and less confusion for everyone involved.  Taking 2-3 patches is just as
easy as 1 patch, and even easier if I don't have to review it as
"hard"
due to it not differing from what is in Linus's tree.

thanks,

greg k-h

On (Tue) 12 Aug 2014 [13:55:48], Greg KH wrote:
> On Tue, Aug 12, 2014 at 11:01:58AM +0530, Amit Shah wrote:
> > On (Tue) 12 Aug 2014 [06:55:27], Greg KH wrote:
> > > On Mon, Aug 11, 2014 at 06:11:47PM +0530, Amit Shah wrote:
> > > > This is a 3.16-only patch.  The linux.git fix is
> > > > 5c06273401f2eb7b290cadbae18ee00f8f65e893, which fixes this
issue in a
> > > > different way.
> > > 
> > > Why "different"?  Why can't I take that original
patch instead?  What is
> > > different in this patch, and why?
> > 
> > The commit referenced moves the hwrng_register() call to the
->scan()
> > callback instead of it being in probe().  This was done to ensure the
> > virtio-rng devices can contribute to the initial system entropy
> > introduced in commit d9e7972619334.
> > 
> > That patch is quite small too, but will need a slight conflict
> > resolution due to the previous two code-shuffling patches, and also
> > the following revert.
> > 
> > However, I decided against the backport of the ->scan() method,
since
> > it wasn't designed to solve this regression, it happens to solve
it,
> > and it actually introduces new functionality.  I would be happy to
> > provide a backport of the relevant patches, if you think that would be
> > alright.
> 
> I almost always want "original" patches as it causes less bugs
overall,
> and less confusion for everyone involved.  Taking 2-3 patches is just as
> easy as 1 patch, and even easier if I don't have to review it as
"hard"
> due to it not differing from what is in Linus's tree.
Thanks; I'll send a backport of the patches, then.

		Amit