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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Petr Machata <petrm@mellanox.com>,
        Jiri Pirko <jiri@mellanox.com>,
        Ido Schimmel <idosch@mellanox.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.14 07/23] mlxsw: __mlxsw_sp_port_headroom_set(): Fix a use of local variable
Date:   Thu, 21 Feb 2019 15:35:49 +0100
Message-Id: <20190221125246.839130601@linuxfoundation.org>
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4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Petr Machata <petrm@mellanox.com>

[ Upstream commit 289460404f6947ef1c38e67d680be9a84161250b ]

The function-local variable "delay" enters the loop interpreted as delay
in bits. However, inside the loop it gets overwritten by the result of
mlxsw_sp_pg_buf_delay_get(), and thus leaves the loop as quantity in
cells. Thus on second and further loop iterations, the headroom for a
given priority is configured with a wrong size.

Fix by introducing a loop-local variable, delay_cells. Rename thres to
thres_cells for consistency.

Fixes: f417f04da589 ("mlxsw: spectrum: Refactor port buffer configuration")
Signed-off-by: Petr Machata <petrm@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum.c |   12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
@@ -1161,8 +1161,9 @@ int __mlxsw_sp_port_headroom_set(struct
 	for (i = 0; i < IEEE_8021QAZ_MAX_TCS; i++) {
 		bool configure = false;
 		bool pfc = false;
+		u16 thres_cells;
+		u16 delay_cells;
 		bool lossy;
-		u16 thres;
 
 		for (j = 0; j < IEEE_8021QAZ_MAX_TCS; j++) {
 			if (prio_tc[j] == i) {
@@ -1176,10 +1177,11 @@ int __mlxsw_sp_port_headroom_set(struct
 			continue;
 
 		lossy = !(pfc || pause_en);
-		thres = mlxsw_sp_pg_buf_threshold_get(mlxsw_sp, mtu);
-		delay = mlxsw_sp_pg_buf_delay_get(mlxsw_sp, mtu, delay, pfc,
-						  pause_en);
-		mlxsw_sp_pg_buf_pack(pbmc_pl, i, thres + delay, thres, lossy);
+		thres_cells = mlxsw_sp_pg_buf_threshold_get(mlxsw_sp, mtu);
+		delay_cells = mlxsw_sp_pg_buf_delay_get(mlxsw_sp, mtu, delay,
+							pfc, pause_en);
+		mlxsw_sp_pg_buf_pack(pbmc_pl, i, thres_cells + delay_cells,
+				     thres_cells, lossy);
 	}
 
 	return mlxsw_reg_write(mlxsw_sp->core, MLXSW_REG(pbmc), pbmc_pl);