net/mlx4: optimize stuck memory size in probe

  The mlx4_pci_probe function sets a pointer to the mlx4_priv structure,
and during that function fills its fields one by one with relevant
values.

It wants to put a value in the intr_handle field that has all its fields
zero except 2. To do so, it initializes a local struct rte_intr_handle
type variable and updates it only 2 fields and assigns it into the
appropriate field. However, it initializes a very large structure on the
stack while not at all certain that this place exists and in any case it
is very wasteful.

Reset all fields directly to the pointer by memset, then format the 2
fields to the relevant values.

Fixes: 63c2f23c852a ("net/mlx4: use a single interrupt handle")
Cc: stable@dpdk.org

Signed-off-by: Michael Baum <michaelba@mellanox.com>
Acked-by: Matan Azrad <matan@mellanox.com>
---
 drivers/net/mlx4/mlx4.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)
  

Hi,

> -----Original Message-----
> From: dev <dev-bounces@dpdk.org> On Behalf Of Michael Baum
> Sent: Tuesday, July 21, 2020 3:01 PM
> To: dev@dpdk.org
> Cc: Matan Azrad <matan@mellanox.com>; Slava Ovsiienko
> <viacheslavo@mellanox.com>; stable@dpdk.org
> Subject: [dpdk-dev] [PATCH] net/mlx4: optimize stuck memory size in probe
> 
> The mlx4_pci_probe function sets a pointer to the mlx4_priv structure,
> and during that function fills its fields one by one with relevant
> values.
> 
> It wants to put a value in the intr_handle field that has all its fields
> zero except 2. To do so, it initializes a local struct rte_intr_handle
> type variable and updates it only 2 fields and assigns it into the
> appropriate field. However, it initializes a very large structure on the
> stack while not at all certain that this place exists and in any case it
> is very wasteful.
> 
> Reset all fields directly to the pointer by memset, then format the 2
> fields to the relevant values.
> 
> Fixes: 63c2f23c852a ("net/mlx4: use a single interrupt handle")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Michael Baum <michaelba@mellanox.com>
> Acked-by: Matan Azrad <matan@mellanox.com>
> ---
>  drivers/net/mlx4/mlx4.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/mlx4/mlx4.c b/drivers/net/mlx4/mlx4.c
> index e619a74..71061a7 100644
> --- a/drivers/net/mlx4/mlx4.c
> +++ b/drivers/net/mlx4/mlx4.c
> @@ -1029,10 +1029,9 @@ struct mlx4_conf {
>  		eth_dev->device = &pci_dev->device;
>  		rte_eth_copy_pci_info(eth_dev, pci_dev);
>  		/* Initialize local interrupt handle for current port. */
> -		priv->intr_handle = (struct rte_intr_handle){
> -			.fd = -1,
> -			.type = RTE_INTR_HANDLE_EXT,
> -		};
> +		memset(&priv->intr_handle, 0, sizeof(struct
> rte_intr_handle));
> +		priv->intr_handle.fd = -1;
> +		priv->intr_handle.type = RTE_INTR_HANDLE_EXT;
>  		/*
>  		 * Override ethdev interrupt handle pointer with private
>  		 * handle instead of that of the parent PCI device used by
> --
> 1.8.3.1


Patch applied to next-net-mlx

Kindest regards,
Raslan Darawsheh