From ddbc251be18fb82884ee6e9af634cc9f1171a4d6 Mon Sep 17 00:00:00 2001 From: Michael Guralnik Date: Wed, 10 Jun 2026 03:01:44 +0300 Subject: [PATCH] RDMA/core: Add ib_frmr_pool_drop for unrecoverable handles A driver that has popped a handle from an FRMR pool can hit failures that leave the handle in a state where it can't safely be returned for reuse. The driver destroys the handle itself, but the pool has no way to learn about it, so the in_use counter drifts upward. Add ib_frmr_pool_drop to balance the pool's accounting in this case. Every pop is now balanced by exactly one push or drop. Fixes: 36680ef7bceb ("RDMA/mlx5: Switch from MR cache to FRMR pools") Link: https://patch.msgid.link/r/20260610000145.820592-9-michaelgur@nvidia.com Signed-off-by: Michael Guralnik Signed-off-by: Jason Gunthorpe --- drivers/infiniband/core/frmr_pools.c | 15 +++++++++++++++ include/rdma/frmr_pools.h | 1 + 2 files changed, 16 insertions(+) diff --git a/drivers/infiniband/core/frmr_pools.c b/drivers/infiniband/core/frmr_pools.c index e214a8273df8..ce8ae4305b9c 100644 --- a/drivers/infiniband/core/frmr_pools.c +++ b/drivers/infiniband/core/frmr_pools.c @@ -578,3 +578,18 @@ void ib_frmr_pool_push(struct ib_device *device, struct ib_mr *mr) } EXPORT_SYMBOL(ib_frmr_pool_push); + +/* + * Drop a handle previously popped from the pool without returning it for + * reuse. The caller is responsible for destroying the underlying hardware + * resource. + */ +void ib_frmr_pool_drop(struct ib_mr *mr) +{ + struct ib_frmr_pool *pool = mr->frmr.pool; + + spin_lock(&pool->lock); + pool->in_use--; + spin_unlock(&pool->lock); +} +EXPORT_SYMBOL(ib_frmr_pool_drop); diff --git a/include/rdma/frmr_pools.h b/include/rdma/frmr_pools.h index 5b57bafa3636..aed4d69d3841 100644 --- a/include/rdma/frmr_pools.h +++ b/include/rdma/frmr_pools.h @@ -35,5 +35,6 @@ int ib_frmr_pools_init(struct ib_device *device, void ib_frmr_pools_cleanup(struct ib_device *device); int ib_frmr_pool_pop(struct ib_device *device, struct ib_mr *mr); void ib_frmr_pool_push(struct ib_device *device, struct ib_mr *mr); +void ib_frmr_pool_drop(struct ib_mr *mr); #endif /* FRMR_POOLS_H */