net/mlx4_core: Fix use of ENOSPC around mlx4_counter_alloc()

stable inclusion
from linux-4.19.123
commit b350c15a291bb08c81c30bf949056d64a4ca1a8f

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

[ Upstream commit 40e47307 ]

When ENOSPC is set the idx is still valid and gets set to the global
MLX4_SINK_COUNTER_INDEX.  However gcc's static analysis cannot tell that
ENOSPC is impossible from mlx4_cmd_imm() and gives this warning:

drivers/net/ethernet/mellanox/mlx4/main.c:2552:28: warning: 'idx' may be
used uninitialized in this function [-Wmaybe-uninitialized]
 2552 |    priv->def_counter[port] = idx;

Also, when ENOSPC is returned mlx4_allocate_default_counters should not
fail.

Fixes: 6de5f7f6 ("net/mlx4_core: Allocate default counter per port")
Signed-off-by: NJason Gunthorpe <jgg@mellanox.com>
Signed-off-by: NTariq Toukan <tariqt@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Signed-off-by: NLi Aichun <liaichun@huawei.com>
Reviewed-by: Nguodeqing <geffrey.guo@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

drivers/net/ethernet/mellanox/mlx4/main.c

@@ -2539,6 +2539,7 @@ static int mlx4_allocate_default_counters(struct mlx4_dev *dev)
 
 		if (!err || err == -ENOSPC) {
 			priv->def_counter[port] = idx;
+			err = 0;
 		} else if (err == -ENOENT) {
 			err = 0;
 			continue;
@@ -2589,7 +2590,8 @@ int mlx4_counter_alloc(struct mlx4_dev *dev, u32 *idx, u8 usage)
 				   MLX4_CMD_TIME_CLASS_A, MLX4_CMD_WRAPPED);
 		if (!err)
 			*idx = get_param_l(&out_param);
-
+		if (WARN_ON(err == -ENOSPC))
+			err = -EINVAL;
 		return err;
 	}
 	return __mlx4_counter_alloc(dev, idx);