4.19-stable review patch. If anyone has any objections, please let me know.
------------------
From: Dave Jiang <dave.jiang@xxxxxxxxx>
commit 5a7693e6bbf19b22fd6c1d2c4b7beb0a03969e2c upstream.
ntb_transport_tx_free_entry() never returns 0 with the current
calculation. If head == tail, then it would return qp->tx_max_entry.
Change compare to tail >= head and when they are equal, a 0 would be
returned.
Fixes: e74bfeedad08 ("NTB: Add flow control to the ntb_netdev")
Reviewed-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Signed-off-by: renlonglong <ren.longlong@xxxxxxx>
Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx>
Signed-off-by: Jon Mason <jdmason@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/ntb/ntb_transport.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/ntb/ntb_transport.c
+++ b/drivers/ntb/ntb_transport.c
@@ -2199,7 +2199,7 @@ unsigned int ntb_transport_tx_free_entry
unsigned int head = qp->tx_index;
unsigned int tail = qp->remote_rx_info->entry;
- return tail > head ? tail - head : qp->tx_max_entry + tail - head;
+ return tail >= head ? tail - head : qp->tx_max_entry + tail - head;
}
EXPORT_SYMBOL_GPL(ntb_transport_tx_free_entry);
