From 5a3e327dc3fdf9586d3ed00f82e41b54f2c1e2af Mon Sep 17 00:00:00 2001 From: Dave Jiang Date: Tue, 22 Aug 2023 09:04:57 -0700 Subject: [PATCH] ntb: Fix calculation ntb_transport_tx_free_entry() 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 Signed-off-by: renlonglong Signed-off-by: Dave Jiang Signed-off-by: Jon Mason Signed-off-by: Greg Kroah-Hartman --- drivers/ntb/ntb_transport.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/ntb/ntb_transport.c b/drivers/ntb/ntb_transport.c index 7884ea9c7643f..9532108d2dce1 100644 --- a/drivers/ntb/ntb_transport.c +++ b/drivers/ntb/ntb_transport.c @@ -2429,7 +2429,7 @@ unsigned int ntb_transport_tx_free_entry(struct ntb_transport_qp *qp) 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);