[PATCH net-next v4 0/3] net/smc: transition to RDMA core CQ pooling

["D. Wythe" <alibuda@linux.alibaba.com>]

This series transitions SMC-R completion handling to RDMA core CQ pooling
via the ib_cqe API. The new completion model improves scalability by
allowing per-link completion processing across multiple cores and enables
DIM-based interrupt moderation.

The increased concurrency can amplify contention for TX slots on the shared
wait queue, so the exclusive-wait change comes first as a standalone
improvement that the CQ pooling teardown then builds on.

Patch 1 fixes smc_wr_tx_put_slot() to clear the v2 pending slot and buffer
structures instead of the pointer variables.
Patch 2 reduces TX slot contention by switching TX slot allocation from
non-exclusive wait_event() to prepare_to_wait_exclusive().
Patch 3 replaces the global per-device CQ and manual tasklet polling model
with RDMA core CQ pooling.

Link: https://lore.kernel.org/netdev/20260305022323.96125-1-alibuda@linux.alibaba.com/

---
Changes v1 -> v2:
https://lore.kernel.org/netdev/20260508063718.101622-1-alibuda@linux.alibaba.com/
1. remove unnecessary inline from static CQE init helpers.
2. Use ib_drain_qp() with +1 max_send_wr;
3. Fix v2 state clearing.
4. Add re-check after schedule_timeout() to fix timeout/signal races.

Changes v2 -> v3:
https://lore.kernel.org/netdev/20260528084819.6059-1-alibuda@linux.alibaba.com/
1. Reserve +3 instead of +1 for the SQ to cover the drain, FastReg and
   SMC-Rv2 SEND WRs, avoiding SQ exhaustion that breaks ib_drain_sq().
2. Guard the recv WR repost with a per-link percpu_ref so no WR is
   reposted after ib_drain_qp(), fixing the RX repost/drain use-after-free.
3. Split the smc_wr_tx_put_slot() v2 clearing fix into a separate patch
   (1/3) with a Fixes: tag and reworded to the verifiable root cause.

Changes v3 -> v4:
https://lore.kernel.org/netdev/20260710033356.16460-1-alibuda@linux.alibaba.com/
1. Reorder: move the exclusive-wait patch before the CQ pooling patch.
2. Fix teardown stall: reintroduce smc_ib_modify_qp_error() and flush the QP
   in smc_wr_stop_link() before waiting for the refs.
3. smc_wr_reg_send(): take the ref before ib_post_send().
4. smc_wr_tx_process_cqe(): wake_up_all() on a flush completion.
5. Merge the three per-link percpu_refs into a single wr_refs.

D. Wythe (3):
  net/smc: clear the correct v2 slot and buffer in smc_wr_tx_put_slot()
  net/smc: reduce TX slot contention with exclusive wait
  net/smc: transition to RDMA core CQ pooling

 net/smc/smc_core.c |  10 +-
 net/smc/smc_core.h |  36 ++--
 net/smc/smc_ib.c   | 106 ++++-------
 net/smc/smc_ib.h   |   6 -
 net/smc/smc_tx.c   |   1 -
 net/smc/smc_wr.c   | 445 +++++++++++++++++++++------------------------
 net/smc/smc_wr.h   |  50 ++---
 7 files changed, 287 insertions(+), 367 deletions(-)

-- 
2.45.0