IB/mlx4: Fix stale CM id_map entries when RTU is never received

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mlx4_ib_multiplex_cm_handler() allocates an id_map_entry for CM
transactions, but the entry is normally released only on DREQ or REJ
flows.

In the duplicate REP handling scenario, cm_dup_rep_handler() may be
invoked when the remote side receives a REP for which no matching
cm_id_priv exists. In such cases the CM handshake never reaches RTU, and
the sender side may never receive either DREQ or REJ cleanup events.

As a result, the allocated id_map_entry remains indefinitely, resulting in
a stale mapping leak.

Fix this by arming an RTU-abandon cleanup timeout when the id_map_entry is
allocated. The timeout uses the mlx4 CM workqueue and the existing
schedule_delayed() path, so later DREQ/REJ cleanup can shorten the pending
timeout with mod_delayed_work().

Track whether a pending cleanup timeout is still waiting for RTU. RTU
cancels only that initial timeout; if DREQ/REJ has already converted it to
normal teardown cleanup, a late or duplicate RTU does not cancel the
teardown timer. If the RTU timeout callback has already started, leave the
entry on the timeout path and make the RTU packet lose that race.

Hold id_map_lock while looking up the entry, canceling the RTU timeout,
scheduling teardown cleanup, and copying the id values needed by the CM
handlers. The delayed-work callback rechecks scheduled_delete under the
same lock before removing and freeing the entry, avoiding use-after-free
when RTU races with timeout execution.

Signed-off-by: Praveen Kumar Kannoju <praveen.kannoju@oracle.com>
Link: https://patch.msgid.link/20260715080738.1357072-1-praveen.kannoju@oracle.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>

...

This commit is contained in:

Praveen Kumar Kannoju 2026-07-15 08:07:38 +00:00 • committed by Leon Romanovsky

parent fbf03a0867

commit fa09adf423

1 changed files with 87 additions and 24 deletions

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drivers/infiniband/hw/mlx4/cm.c

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