On Wed, Jan 30, 2019 at 10:34:02AM +0200, Joel Nider wrote:
> linux-rdma-ow...@vger.kernel.org wrote on 01/29/2019 07:04:06 PM:
>
> > On Tue, Jan 29, 2019 at 03:26:26PM +0200, Joel Nider wrote:
> > > Add a new handler for new uverb reg_remote_mr. The purpose is to
> register
> > > a memory region in a different address space (i.e. process) than the
> > > caller.
> > >
> > > The main use case which motivated this change is post-copy container
> > > migration. When a migration manager (i.e. CRIU) starts a migration, it
> > > must have an open connection for handling any page faults that occur
> > > in the container after restoration on the target machine. Even though
> > > CRIU establishes and maintains the connection, ultimately the memory
> > > is copied from the container being migrated (i.e. a remote address
> > > space). This container must remain passive -- meaning it cannot have
> > > any knowledge of the RDMA connection; therefore the migration manager
> > > must have the ability to register a remote memory region. This remote
> > > memory region will serve as the source for any memory pages that must
> > > be copied (on-demand or otherwise) during the migration.
> > >
> > > Signed-off-by: Joel Nider <jo...@il.ibm.com>
> > > drivers/infiniband/core/uverbs_std_types_mr.c | 129
> +++++++++++++++++++++++++-
> > > include/rdma/ib_verbs.h | 8 ++
> > > include/uapi/rdma/ib_user_ioctl_cmds.h | 13 +++
> > > 3 files changed, 149 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/infiniband/core/uverbs_std_types_mr.c b/drivers/
> > infiniband/core/uverbs_std_types_mr.c
> > > index 4d4be0c..bf7b4b2 100644
> > > +++ b/drivers/infiniband/core/uverbs_std_types_mr.c
> > > @@ -150,6 +150,99 @@ static int
> UVERBS_HANDLER(UVERBS_METHOD_DM_MR_REG)(
> > > return ret;
> > > }
> > >
> > > +static int UVERBS_HANDLER(UVERBS_METHOD_REG_REMOTE_MR)(
> > > + struct uverbs_attr_bundle *attrs)
> > > +{
> >
> > I think this should just be REG_MR with an optional remote PID
> > argument
>
> Maybe I missed something. Isn't REG_MR only implemented as a write()
> command? In our earlier conversation you told me all new commands must be
> implemented as ioctl() commands.
Yes - but we are also converting old write() commands into ioctl()
when they need new functionality. So in this case it should convert
reg_mr to ioctl() then add an optional report PID argument
>
> > > DECLARE_UVERBS_NAMED_OBJECT(
> > > UVERBS_OBJECT_MR,
> > > UVERBS_TYPE_ALLOC_IDR(uverbs_free_mr),
> > > &UVERBS_METHOD(UVERBS_METHOD_DM_MR_REG),
> > > &UVERBS_METHOD(UVERBS_METHOD_MR_DESTROY),
> > > - &UVERBS_METHOD(UVERBS_METHOD_ADVISE_MR));
> > > + &UVERBS_METHOD(UVERBS_METHOD_ADVISE_MR),
> > > + &UVERBS_METHOD(UVERBS_METHOD_REG_REMOTE_MR),
> > > +);
> >
> > I'm kind of surprised this compiles with the trailing comma?
> Personally, I think it is nicer with the trailing comma. Of course
> syntactically it makes no sense, but when adding a new entry, you don't
> have to touch the previous line, which makes the diff cleaner. If this is
> against standard practices I will remove the comma.
Well, it is just that this is a macro call, and you usually can't have
a trailing comma in a function-macro call, at least I thought this was
the case.. Without some study I'm not sure what it expands to, or if
that expansion is even OK..
Jason
