Re: [PATCH rdma-next v3 4/6] RDMA/mana_ib: enable RoCE on port 1

[Nathan Chancellor <nathan@kernel.org>]

Hi Konstantin,

On Wed, Apr 10, 2024 at 01:42:29AM -0700, Konstantin Taranov wrote:
> From: Konstantin Taranov <kotaranov@microsoft.com>
> 
> Set netdev and RoCEv2 flag to enable GID population on port 1.
> Use GIDs of the master netdev. As mc->ports[] stores slave devices,
> use a helper to get the master netdev.
> 
> Signed-off-by: Konstantin Taranov <kotaranov@microsoft.com>
> ---
>  drivers/infiniband/hw/mana/device.c | 15 +++++++++++++++
>  drivers/infiniband/hw/mana/main.c   | 15 +++++++++++----
>  2 files changed, 26 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/infiniband/hw/mana/device.c b/drivers/infiniband/hw/mana/device.c
> index 47547a962b19..e7981301d10b 100644
> --- a/drivers/infiniband/hw/mana/device.c
> +++ b/drivers/infiniband/hw/mana/device.c
> @@ -53,6 +53,7 @@ static int mana_ib_probe(struct auxiliary_device *adev,
>  {
>  	struct mana_adev *madev = container_of(adev, struct mana_adev, adev);
>  	struct gdma_dev *mdev = madev->mdev;
> +	struct net_device *upper_ndev;
>  	struct mana_context *mc;
>  	struct mana_ib_dev *dev;
>  	int ret;
> @@ -79,6 +80,20 @@ static int mana_ib_probe(struct auxiliary_device *adev,
>  	dev->ib_dev.num_comp_vectors = 1;
>  	dev->ib_dev.dev.parent = mdev->gdma_context->dev;
>  
> +	rcu_read_lock(); /* required to get upper dev */
> +	upper_ndev = netdev_master_upper_dev_get_rcu(mc->ports[0]);
> +	if (!upper_ndev) {
> +		rcu_read_unlock();
> +		ibdev_err(&dev->ib_dev, "Failed to get master netdev");
> +		goto free_ib_device;
> +	}

Clang now warns (or errors with CONFIG_WERROR):

  drivers/infiniband/hw/mana/device.c:88:6: error: variable 'ret' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
     88 |         if (!upper_ndev) {
        |             ^~~~~~~~~~~
  drivers/infiniband/hw/mana/device.c:150:9: note: uninitialized use occurs here
    150 |         return ret;
        |                ^~~
  drivers/infiniband/hw/mana/device.c:88:2: note: remove the 'if' if its condition is always false
     88 |         if (!upper_ndev) {
        |         ^~~~~~~~~~~~~~~~~~
     89 |                 rcu_read_unlock();
        |                 ~~~~~~~~~~~~~~~~~~
     90 |                 ibdev_err(&dev->ib_dev, "Failed to get master netdev");
        |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     91 |                 goto free_ib_device;
        |                 ~~~~~~~~~~~~~~~~~~~~
     92 |         }
        |         ~
  drivers/infiniband/hw/mana/device.c:62:9: note: initialize the variable 'ret' to silence this warning
     62 |         int ret;
        |                ^
        |                 = 0
  1 error generated.

I could not really find a consistent return code for when
netdev_master_upper_dev_get_rcu() fails. -ENODEV?

Cheers,
Nathan

> +	ret = ib_device_set_netdev(&dev->ib_dev, upper_ndev, 1);
> +	rcu_read_unlock();
> +	if (ret) {
> +		ibdev_err(&dev->ib_dev, "Failed to set ib netdev, ret %d", ret);
> +		goto free_ib_device;
> +	}
> +
>  	ret = mana_gd_register_device(&mdev->gdma_context->mana_ib);
>  	if (ret) {
>  		ibdev_err(&dev->ib_dev, "Failed to register device, ret %d",
> diff --git a/drivers/infiniband/hw/mana/main.c b/drivers/infiniband/hw/mana/main.c
> index 29550f2173ff..7a9d7e13b7b1 100644
> --- a/drivers/infiniband/hw/mana/main.c
> +++ b/drivers/infiniband/hw/mana/main.c
> @@ -527,11 +527,18 @@ int mana_ib_mmap(struct ib_ucontext *ibcontext, struct vm_area_struct *vma)
>  int mana_ib_get_port_immutable(struct ib_device *ibdev, u32 port_num,
>  			       struct ib_port_immutable *immutable)
>  {
> -	/*
> -	 * This version only support RAW_PACKET
> -	 * other values need to be filled for other types
> -	 */
> +	struct ib_port_attr attr;
> +	int err;
> +
> +	err = ib_query_port(ibdev, port_num, &attr);
> +	if (err)
> +		return err;
> +
> +	immutable->pkey_tbl_len = attr.pkey_tbl_len;
> +	immutable->gid_tbl_len = attr.gid_tbl_len;
>  	immutable->core_cap_flags = RDMA_CORE_PORT_RAW_PACKET;
> +	if (port_num == 1)
> +		immutable->core_cap_flags |= RDMA_CORE_PORT_IBA_ROCE_UDP_ENCAP;
>  
>  	return 0;
>  }
> -- 
> 2.43.0
>