[PATCH] net/mlx5: reduce stack usage in qp_read_field

From: Arnd Bergmann
Date: Tue Apr 28 2020 - 17:24:19 EST


Moving the mlx5_ifc_query_qp_out_bits structure on the stack was a bit
excessive and now causes the compiler to complain on 32-bit architectures:

drivers/net/ethernet/mellanox/mlx5/core/debugfs.c: In function 'qp_read_field':
drivers/net/ethernet/mellanox/mlx5/core/debugfs.c:274:1: error: the frame size of 1104 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]

Revert the previous patch partially to use dynamically allocation as
the code did before. Unfortunately there is no good error handling
in case the allocation fails.

Fixes: 57a6c5e992f5 ("net/mlx5: Replace hand written QP context struct with automatic getters")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
drivers/net/ethernet/mellanox/mlx5/core/debugfs.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/debugfs.c b/drivers/net/ethernet/mellanox/mlx5/core/debugfs.c
index 6409090b3ec5..d2d57213511b 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/debugfs.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/debugfs.c
@@ -202,18 +202,23 @@ void mlx5_cq_debugfs_cleanup(struct mlx5_core_dev *dev)
static u64 qp_read_field(struct mlx5_core_dev *dev, struct mlx5_core_qp *qp,
int index, int *is_str)
{
- u32 out[MLX5_ST_SZ_BYTES(query_qp_out)] = {};
+ int outlen = MLX5_ST_SZ_BYTES(query_qp_out);
u32 in[MLX5_ST_SZ_DW(query_qp_in)] = {};
u64 param = 0;
+ u32 *out;
int state;
u32 *qpc;
int err;

+ out = kzalloc(outlen, GFP_KERNEL);
+ if (!out)
+ return 0;
+
MLX5_SET(query_qp_in, in, opcode, MLX5_CMD_OP_QUERY_QP);
MLX5_SET(query_qp_in, in, qpn, qp->qpn);
err = mlx5_cmd_exec_inout(dev, query_qp, in, out);
if (err)
- return 0;
+ goto out;

*is_str = 0;

@@ -269,7 +274,8 @@ static u64 qp_read_field(struct mlx5_core_dev *dev, struct mlx5_core_qp *qp,
param = MLX5_GET(qpc, qpc, remote_qpn);
break;
}
-
+out:
+ kfree(out);
return param;
}

--
2.26.0