Linux Virtualization - Aug 2020 - [PATCH V4 linux-next 00/12] VDPA support for Mellanox ConnectX devices

On Wed, Aug 05, 2020 at 04:01:58PM +0300, Eli Cohen
wrote:
> On Wed, Aug 05, 2020 at 08:48:52AM -0400, Michael S. Tsirkin wrote:
> > > 
> > > Did you merge this?:
> > > git pull
git://git.kernel.org/pub/scm/linux/kernel/git/mellanox/linux.git mlx5-next
> > 
> > 
> > I can only merge this tree if no one else will. Linus does not like
> > getting same patches through two trees.
> > 
> > Is this the case? Is mlx5-next going to be merged through
> > my tree in this cycle?
> > 
> 
> Saeed Mahameed from Mellanox (located in California) usuaally sends out
> net patches. So he's supposed to send that to Dave Miller.
> 
> I think Saeed should answer this. Let's wait a few more hours till he
> wakes up.
Alternatives:
- merge vdpa through Saeed's tree. I can ack that, we'll need to
  resolve any conflicts by merging the two trees and show the
  result to Linus so he can resolve the merge in the same way.
- extract just the necessary patches that are needed for vdpa and
  merge through my tree.
- if Saeed sends his pull today, it's likely it will be merged
  early next week. Then I can rebase and send a pull with your patches
  on top. A bit risky.
- do some tricks with build. E.g. disable build of your code,
  and enable in Saeed's tree when everything is merged together.
  Can be somewhat hard.

On Wed, 2020-08-05 at 09:12 -0400, Michael S. Tsirkin
wrote:
> On Wed, Aug 05, 2020 at 04:01:58PM +0300, Eli Cohen wrote:
> > On Wed, Aug 05, 2020 at 08:48:52AM -0400, Michael S. Tsirkin wrote:
> > > > Did you merge this?:
> > > > git pull
> > > >
git://git.kernel.org/pub/scm/linux/kernel/git/mellanox/linux.gi
> > > > t mlx5-next
> > > 
> > > I can only merge this tree if no one else will. Linus does not
> > > like
> > > getting same patches through two trees.
> > > 
> > > Is this the case? Is mlx5-next going to be merged through
> > > my tree in this cycle?
> > > 
> > 
> > Saeed Mahameed from Mellanox (located in California) usuaally sends
> > out
> > net patches. So he's supposed to send that to Dave Miller.
> > 
> > I think Saeed should answer this. Let's wait a few more hours till
> > he
> > wakes up.
> 
> Alternatives:
> - merge vdpa through Saeed's tree. I can ack that, we'll need to
>   resolve any conflicts by merging the two trees and show the
>   result to Linus so he can resolve the merge in the same way.
> - extract just the necessary patches that are needed for vdpa and
>   merge through my tree.
> - if Saeed sends his pull today, it's likely it will be merged
>   early next week. Then I can rebase and send a pull with your
> patches
>   on top. A bit risky.
> - do some tricks with build. E.g. disable build of your code,
>   and enable in Saeed's tree when everything is merged together.
>   Can be somewhat hard.
> 
Hi Michael,

We do this all the time with net-next and rdma,
mlx5-next is a very small branch based on a very early rc that includes
mlx5 shared stuff between rdma and net-next, and now virtio as well.

we send pull requests of mlx5-next to both rdma and net-next with the
respective features, exactly as we did here, and it works nicely, since
we reduce the number of conflicts to 0 between different subsystems
that rely on mlx5 core.

all the alternative you suggested have never been tried before :),
net-next is Closed, so i can't do further submissions.

On Wed, Aug 05, 2020 at 07:01:52PM +0000, Saeed Mahameed
wrote:
> On Wed, 2020-08-05 at 09:12 -0400, Michael S. Tsirkin wrote:
> > On Wed, Aug 05, 2020 at 04:01:58PM +0300, Eli Cohen wrote:
> > > On Wed, Aug 05, 2020 at 08:48:52AM -0400, Michael S. Tsirkin
wrote:
> > > > > Did you merge this?:
> > > > > git pull
> > > > >
git://git.kernel.org/pub/scm/linux/kernel/git/mellanox/linux.gi
> > > > > t mlx5-next
> > > > 
> > > > I can only merge this tree if no one else will. Linus does
not
> > > > like getting same patches through two trees.
This is not quite the case

Linus does not like multiple *copies* of the same patches. The same
actual git commits can be OK.

Linus also does not like unnecessarily cross linking trees, mlx5-next
is designed to be small enough and approved enough that it is not
controversial.

Linus really doesn't like it when people jams stuff together in rc7 or
the weeks of the merge window. He wants to see stuff be in linux-next
for at least a bit. So it may be too late regardless.
> We do this all the time with net-next and rdma,
> mlx5-next is a very small branch based on a very early rc that includes
> mlx5 shared stuff between rdma and net-next, and now virtio as well.
Yes, going on two years now? Been working well

Jason