[RFC PATCH v4 17/38] NTB: ntb_transport: Dynamically determine qp count
From: Koichiro Den <hidden>
Date: 2026-01-18 13:55:30
Also in:
dmaengine, linux-devicetree, linux-doc, linux-iommu, linux-kselftest, linux-pci, linux-renesas-soc, lkml
Subsystem:
ntb driver core, the rest · Maintainers:
Jon Mason, Dave Jiang, Allen Hubbe, Linus Torvalds
One MW can host multiple queue pairs, so stop limiting qp_count to the number of MWs. Now that both TX and RX MW sizing are done in the same place, the MW layout is derived from a single code path on both host and endpoint, so the layout cannot diverge between the two sides. Signed-off-by: Koichiro Den <redacted> --- drivers/ntb/ntb_transport.c | 26 +++++++++++++++++++++++--- 1 file changed, 23 insertions(+), 3 deletions(-)
diff --git a/drivers/ntb/ntb_transport.c b/drivers/ntb/ntb_transport.c
index 57a21f2daac6..6ed680d0470f 100644
--- a/drivers/ntb/ntb_transport.c
+++ b/drivers/ntb/ntb_transport.c@@ -1022,7 +1022,9 @@ static void ntb_transport_link_work(struct work_struct *work) container_of(work, struct ntb_transport_ctx, link_work.work); struct ntb_dev *ndev = nt->ndev; struct pci_dev *pdev = ndev->pdev; + struct ntb_transport_qp *qp; resource_size_t size; + u64 qp_bitmap_free; u32 val; int rc = 0, i, spad;
@@ -1070,8 +1072,28 @@ static void ntb_transport_link_work(struct work_struct *work) val = ntb_spad_read(ndev, NUM_QPS); dev_dbg(&pdev->dev, "Remote max number of qps = %d\n", val); - if (val != nt->qp_count) + if (val == 0) { goto out; + } else if (val < nt->qp_count) { + /* + * Clamp local qp_count to peer-advertised NUM_QPS to avoid + * mismatched queues. + */ + qp_bitmap_free = nt->qp_bitmap_free; + for (i = val; i < nt->qp_count; i++) { + qp = &nt->qp_vec[i]; + ntb_transport_free_queue(qp); + debugfs_remove_recursive(qp->debugfs_dir); + + /* Do not expose the queue any longer */ + nt->qp_bitmap &= ~BIT_ULL(i); + nt->qp_bitmap_free &= ~BIT_ULL(i); + } + dev_warn(&pdev->dev, + "Local number of qps is reduced: %d->%d (%#llx->%#llx)\n", + nt->qp_count, val, qp_bitmap_free, nt->qp_bitmap_free); + nt->qp_count = val; + } val = ntb_spad_read(ndev, NUM_MWS); dev_dbg(&pdev->dev, "Remote number of mws = %d\n", val);
@@ -1300,8 +1322,6 @@ static int ntb_transport_probe(struct ntb_client *self, struct ntb_dev *ndev) if (max_num_clients && max_num_clients < qp_count) qp_count = max_num_clients; - else if (nt->mw_count < qp_count) - qp_count = nt->mw_count; qp_bitmap &= BIT_ULL(qp_count) - 1;
--
2.51.0