net/mlx5e: Set PTP channel pointer explicitly to NULL

[ Upstream commit 1c2cdf0 ]

When closing the PTP channel, set its pointer explicitly to NULL. PTP
channel is opened on demand, the code verify the pointer validity before
access. Nullify it when closing the PTP channel to avoid unexpected
behavior.

Fixes: 145e563 ("net/mlx5e: Add TX PTP port object support")
Signed-off-by: Aya Levin <ayal@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/net/ethernet/mellanox/mlx5/core/en_main.c

@@ -2443,8 +2443,10 @@ void mlx5e_close_channels(struct mlx5e_channels *chs)
 {
 	int i;
 
-	if (chs->port_ptp)
+	if (chs->port_ptp) {
 		mlx5e_port_ptp_close(chs->port_ptp);
+		chs->port_ptp = NULL;
+	}
 
 	for (i = 0; i < chs->num; i++)
 		mlx5e_close_channel(chs->c[i]);