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RDMA/core: Prevent rereg_mr for dmabuf umems

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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>
This commit is contained in:
Jacob Moroni 2026-07-28 14:15:00 +00:00 committed by Leon Romanovsky
parent 43598807f7
commit 09d09e5d79
1 changed files with 3 additions and 0 deletions
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3
drivers/infiniband/core/umem.c
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@ -677,6 +677,9 @@ int ib_umem_check_rereg(struct ib_umem *umem, int flags, int new_access_flags)
if (!umem)
return 0;
if (umem->is_dmabuf)
return -EOPNOTSUPP;
if ((flags & IB_MR_REREG_ACCESS) && !(flags & IB_MR_REREG_TRANS))
if (ib_access_writable(new_access_flags) && !umem->writable)
return -EACCES;