RDMA/core: Prevent rereg_mr for dmabuf umems

The rereg_mr method has always been explicitly blocked in
rdma-core for dmabuf MRs anyway, so add a check to the
ib_umem_check_rereg helper so that each driver doesn't need
to handle it.

Depending on how the driver handled rereg_mr, this also
has the benefit of preventing rereg_mr from being used
to add the IB_ACCESS_MW_BIND flag to a dmabuf MR. This
flag is not allowed during registration, so it seems
sensible to prevent it from being added back with rereg_mr.

Preventing IB_ACCESS_MW_BIND is important for drivers that
support revocable dmabufs and implement "revoke" by issuing
a dereg_mr command to the HW because most(?) HW will reject
this command if the MR has windows bound to it, and a failure
to revoke is supposed to trigger a function reset.

Signed-off-by: Jacob Moroni <jmoroni@google.com>
Link: https://patch.msgid.link/20260728141501.1425737-1-jmoroni@google.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>

0 files changed, 0 insertions, 0 deletions