Re: [PATCH mptcp-next v2] mptcp: pm: exit early with ADD_ADDR echo if possible

[Geliang Tang <geliang@kernel.org>]

Hi Matt,

On Wed, 2025-02-26 at 15:21 +0100, Matthieu Baerts (NGI0) wrote:
> When the userspace PM is used, or when the in-kernel limits are
> reached,
> there will be no need to schedule the PM worker to signal new
> addresses.
> That corresponds to pm->work_pending set to 0.
> 
> In this case, an early exit can be done in mptcp_pm_add_addr_echoed()
> not to hold the PM lock, and iterate over the announced addresses
> list,
> not to schedule the worker anyway in this case. This is similar to
> what
> is done when a connection or a subflow has been established.
> 
> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>

This v2 looks good to me, thanks.

Reviewed-by: Geliang Tang <geliang@kernel.org>

> ---
> Changes in v2:
> - Link to v1:
> https://lore.kernel.org/r/20250224-mptcp-userspace-avoid-worker-v1-1-127325d3e9a4@kernel.org
> ---
> Notes:
> - v2:
>   - Only modify mptcp_pm_add_addr_echoed().
>   - The rest doesn't need to or shouldn't be modified (Geliang).
> Cc: Geliang Tang <tanggeliang@kylinos.cn>
> ---
>  net/mptcp/pm.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
> index
> 16cacce6c10fe86467aa7ef8e588f9f535b586fb..6c8cadf84f31f4c7dcc38b787be
> da048d5362dc8 100644
> --- a/net/mptcp/pm.c
> +++ b/net/mptcp/pm.c
> @@ -251,6 +251,9 @@ void mptcp_pm_add_addr_echoed(struct mptcp_sock
> *msk,
>  
>  	pr_debug("msk=%p\n", msk);
>  
> +	if (!READ_ONCE(pm->work_pending))
> +		return;
> +
>  	spin_lock_bh(&pm->lock);
>  
>  	if (mptcp_lookup_anno_list_by_saddr(msk, addr) &&
> READ_ONCE(pm->work_pending))
> 
> ---
> base-commit: 1238896935ea03f333a183a32fab666cc0c20e3b
> change-id: 20250224-mptcp-userspace-avoid-worker-93f367e39ca6
> 
> Best regards,