Re: [PATCH mptcp-next v8 04/12] mptcp: sysctl: map path_manager to pm_type

[Matthieu Baerts <matttbe@kernel.org>]

Hi Geliang,

On 04/03/2025 12:40, Geliang Tang wrote:
> From: Geliang Tang <tanggeliang@kylinos.cn>
> 
> This patch maps the newly added path manager sysctl "path_manager"
> to the old one "pm_type".
> 
> Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
> ---
>  net/mptcp/ctrl.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c
> index d425fcbd036a..a158a337cdb5 100644
> --- a/net/mptcp/ctrl.c
> +++ b/net/mptcp/ctrl.c
> @@ -200,6 +200,9 @@ static int mptcp_set_path_manager(char *path_manager, const char *name)
>  static int proc_path_manager(const struct ctl_table *ctl, int write,
>  			     void *buffer, size_t *lenp, loff_t *ppos)
>  {
> +	struct mptcp_pernet *pernet = container_of(ctl->data,
> +						   struct mptcp_pernet,
> +						   path_manager);
>  	char (*path_manager)[MPTCP_PM_NAME_MAX] = ctl->data;
>  	char val[MPTCP_PM_NAME_MAX];
>  	const struct ctl_table tbl = {
> @@ -211,8 +214,14 @@ static int proc_path_manager(const struct ctl_table *ctl, int write,
>  	strscpy(val, *path_manager, MPTCP_PM_NAME_MAX);
>  
>  	ret = proc_dostring(&tbl, write, buffer, lenp, ppos);
> -	if (write && ret == 0)
> +	if (write && ret == 0) {
> +		u8 pm_type = MPTCP_PM_TYPE_KERNEL;
> +
> +		if (!strncmp(val, "userspace", MPTCP_PM_NAME_MAX))

(detail: please use '== 0', that feels more natural than "not strncmp")

> +			pm_type = MPTCP_PM_TYPE_USERSPACE;
> +		pernet->pm_type = pm_type;

Should we not already cope with the future BPF PMs?

  if "kernel":
    pm_type = MPTCP_PM_TYPE_KERNEL;
  elif "userspace:
    pm_type = MPTCP_PM_TYPE_USERSPACE;
  else:
    pm_type = __MPTCP_PM_TYPE_NR;

Please check that this doesn't cause issue to display "pm_type" to 2
here -- note that we should not change the current mptcp_pm_type_max:
the userspace **cannot** set "net.mptcp.pm_type=2".

In other words, please check that this is OK:

  # sysctl net.mptcp.pm_type=2
  sysctl: setting key "net.mptcp.pm_type": Invalid argument
  # sysctl -q net.mptcp.path_manager = "$BPF_PM"
  # sysctl -n net.mptcp.pm_type
  2

>  		ret = mptcp_set_path_manager(*path_manager, val);
> +	}
>  
>  	return ret;
>  }

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.