Patchwork [13/21] NTB: Out of free receive entries issue

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Submitter Jon Mason
Date Jan. 19, 2013, 9:02 a.m.
Message ID <>
Download mbox | patch
Permalink /patch/213784/
State Not Applicable
Delegated to: David Miller
Headers show


Jon Mason - Jan. 19, 2013, 9:02 a.m.
If the NTB client driver enqueues the maximum number of rx buffers, it
will not be able to re-enqueue another in its callback handler due to a
lack of free entries.  This can be avoided by adding the current entry
to the free queue prior to calling the client callback handler.  With
this change, ntb_netdev will no longer encounter a rx error on its first

Signed-off-by: Jon Mason <>
 drivers/ntb/ntb_transport.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)


diff --git a/drivers/ntb/ntb_transport.c b/drivers/ntb/ntb_transport.c
index 69c58da..b3afb24 100644
--- a/drivers/ntb/ntb_transport.c
+++ b/drivers/ntb/ntb_transport.c
@@ -910,12 +910,15 @@  void ntb_transport_free(void *transport)
 static void ntb_rx_copy_task(struct ntb_transport_qp *qp,
 			     struct ntb_queue_entry *entry, void *offset)
-	memcpy(entry->buf, offset, entry->len);
+	void *cb_data = entry->cb_data;
+	unsigned int len = entry->len;
-	if (qp->rx_handler && qp->client_ready == NTB_LINK_UP)
-		qp->rx_handler(qp, qp->cb_data, entry->cb_data, entry->len);
+	memcpy(entry->buf, offset, entry->len);
 	ntb_list_add(&qp->ntb_rx_free_q_lock, &entry->entry, &qp->rx_free_q);
+	if (qp->rx_handler && qp->client_ready == NTB_LINK_UP)
+		qp->rx_handler(qp, qp->cb_data, cb_data, len);
 static int ntb_process_rxc(struct ntb_transport_qp *qp)