On Wed, Mar 18, 2020 at 10:21:00AM -0300, Jason Gunthorpe wrote: > On Wed, Mar 18, 2020 at 03:14:50PM +0200, Leon Romanovsky wrote: > > On Wed, Mar 18, 2020 at 09:54:59AM -0300, Jason Gunthorpe wrote: > > > On Wed, Mar 18, 2020 at 02:43:25PM +0200, Leon Romanovsky wrote: > > > > From: Leon Romanovsky <leonro@xxxxxxxxxxxx> > > > > > > > > From Yishai, > > > > > > > > This series exposes API to enable a dynamic allocation and management of a > > > > UAR which now becomes to be a regular uobject. > > > > > > > > Moving to that mode enables allocating a UAR only upon demand and drop the > > > > redundant static allocation of UARs upon context creation. > > > > > > > > In addition, it allows master and secondary processes that own the same command > > > > FD to allocate and manage UARs according to their needs, this can’t be achieved > > > > today. > > > > > > > > As part of this option, QP & CQ creation flows were adapted to support this > > > > dynamic UAR mode once asked by user space. > > > > > > > > Once this mode is asked by mlx5 user space driver on a given context, it will > > > > be mutual exclusive, means both the static and legacy dynamic modes for using > > > > UARs will be blocked. > > > > > > > > The legacy modes are supported for backward compatible reasons, looking > > > > forward we expect this new mode to be the default. > > > > > > We are starting to accumulate a lot of code that is now old-rdma-core > > > only. > > > > Agree > > > > > > > > I have been wondering if we should add something like > > > > > > #if CONFIG_INFINIBAND_MIN_RDMA_CORE_VERSION < 21 > > > #endif > > > > From one side it will definitely help to see old code, but from another > > it will create many ifdef inside of the code with a very little chance > > of testing. Also we will continue to have the same problem to decide when > > we can delete this code. > > Well, it doesn't have to be an #ifdef, eg just sticking > > if (CONFIG_INFINIBAND_MIN_RDMA_CORE_VERSION >= 21) > return -ENOPROTOOPT; > > at the top of obsolete functions would go a long way First, how will you set this min_version? hordcoded in the kernel code? Second, it will work for simple flows, but can be extremely complex if your code looks like: if (old_version) do something if (new version) do something else You will need to add logic to handle this -ENOPROTOOPT error value. > > > > So we can keep track of what is actually a used code flow and what is > > > now hard to test legacy code. > > > > > > eg this config would also disable the write interface(), turn off > > > compat write interfaces as they are switched to use ioctl, etc, etc. > > > > What about if we introduce one ifdef, let's say CONFIG_INFINIBAND_LEGACY > > and put everything that will be declared as legacy to that bucket? And > > once every 5 (???) years delete everything from that bucket. > > It is much harder to see what is really old vs only a little old > > I'm not sure we can ever completely delete any of this, but at least > the distros can make an informed choice to either do more detailed > test of old libraries or disable those code paths. It will be nice to hear how distros decide to disable/drop the code. Thanks > > Jason
