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| author | Jason Gunthorpe <jgg@nvidia.com> | 2026-06-03 22:27:43 -0300 |
|---|---|---|
| committer | Jason Gunthorpe <jgg@nvidia.com> | 2026-06-08 14:32:43 -0300 |
| commit | 50d5c02ab8e62325548bd3a6e6b758a9dcd6e7c3 (patch) | |
| tree | c767f2731fbc70c4ba83cda09f8a573acaf854e4 /include | |
| parent | ee7a8335069150c3f1893a697ab30bbeca00d796 (diff) | |
| download | lwn-50d5c02ab8e62325548bd3a6e6b758a9dcd6e7c3.tar.gz lwn-50d5c02ab8e62325548bd3a6e6b758a9dcd6e7c3.zip | |
RDMA/nldev: Fix locking when accessing mr->pd
Sashiko points out that, due to rereg_mr, the PD is actually variable and
all the touches in nldev are racy.
Use mr->device instead of mr->pd->device.
Getting the PD restrack ID is more tricky. To avoid disturbing all the
happy paths, add an rdma_restrack_sync() operation which is sort of like
flush_workqueue() or synchronize_irq(): after it returns, all the old
nldev touches to the mr are gone and everything sees the new PD. This
makes it safe to reach into the PD pointer.
Fixes: da5c85078215 ("RDMA/nldev: add driver-specific resource tracking")
Link: https://patch.msgid.link/r/4-v1-29ebd2c229b5+fd5-ib_mr_pd_jgg@nvidia.com
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Diffstat (limited to 'include')
| -rw-r--r-- | include/rdma/ib_verbs.h | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h index 0daa5089d539..794746de8db0 100644 --- a/include/rdma/ib_verbs.h +++ b/include/rdma/ib_verbs.h @@ -1977,6 +1977,11 @@ struct ib_dmah { struct ib_mr { struct ib_device *device; + /* + * Due to IB_MR_REREG_PD pd is not a fixed pointer and can change. For a + * user MR, this value should only be read from a system call that holds + * the uobject lock, or the driver should disable in-place REREG_PD. + */ struct ib_pd *pd; u32 lkey; u32 rkey; |