Re: [net-next V3 13/15] net/mlx5: DR, Change SWS usage to debug fs seq_file interface

[Saeed Mahameed <saeed@kernel.org>]

On 04 Feb 14:24, Simon Horman wrote:
>On Fri, Feb 02, 2024 at 11:08:52AM -0800, Saeed Mahameed wrote:
>> From: Hamdan Igbaria <hamdani@nvidia.com>
>>
>> In current SWS debug dump mechanism we implement the seq_file interface,
>> but we only implement the 'show' callback to dump the whole steering DB
>> with a single call to this callback.
>>
>> However, for large data size the seq_printf function will fail to
>> allocate a buffer with the adequate capacity to hold such data.
>>
>> This patch solves this problem by utilizing the seq_file interface
>> mechanism in the following way:
>>  - when the user triggers a dump procedure, we will allocate a list of
>>    buffers that hold the whole data dump (in the start callback)
>>  - using the start, next, show and stop callbacks of the seq_file
>>    API we iterate through the list and dump the whole data
>>
>> Signed-off-by: Hamdan Igbaria <hamdani@nvidia.com>
>> Reviewed-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
>> Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
>> ---
>>  .../mellanox/mlx5/core/steering/dr_dbg.c      | 735 ++++++++++++++----
>>  .../mellanox/mlx5/core/steering/dr_dbg.h      |  20 +
>>  2 files changed, 620 insertions(+), 135 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_dbg.c b/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_dbg.c
>
>...
>
>> +static struct mlx5dr_dbg_dump_data *
>> +mlx5dr_dbg_create_dump_data(void)
>> +{
>> +	struct mlx5dr_dbg_dump_data *dump_data;
>> +
>> +	dump_data = kzalloc(sizeof(*dump_data), GFP_KERNEL);
>> +	if (!dump_data)
>> +		return NULL;
>> +
>> +	INIT_LIST_HEAD(&dump_data->buff_list);
>> +
>> +	if (!mlx5dr_dbg_dump_data_init_new_buff(dump_data))
>> +		kfree(dump_data);
>
>Hi Hamdan and Saeed,
>
>dump_data may be freed above.
>But it is returned unconditionally below.
>This seems a little odd.
>
>Flagged by Smatch and Coccinelle.
>


Thanks Simon, Fixed in V4.