Re: [PATCH mptcp-next v5 1/9] mptcp: pm: use addr entry for get_local_id

[Matthieu Baerts <matttbe@kernel.org>]

Hi Geliang,

On 20/02/2025 03:57, Geliang Tang wrote:
> From: Geliang Tang <tanggeliang@kylinos.cn>
> 
> The following code in mptcp_userspace_pm_get_local_id() that assigns "skc"
> to "new_entry" is not allowed in BPF if we use the same code to implement
> the get_local_id() interface of a BFP path manager:
> 
> 	memset(&new_entry, 0, sizeof(struct mptcp_pm_addr_entry));
> 	new_entry.addr = *skc;
> 	new_entry.addr.id = 0;
> 	new_entry.flags = MPTCP_PM_ADDR_FLAG_IMPLICIT;
> 
> To solve the issue, this patch moves this assignment to "new_entry" forward
> to mptcp_pm_get_local_id(), and then passing "new_entry" as a parameter to
> both mptcp_pm_nl_get_local_id() and mptcp_userspace_pm_get_local_id().
> 
> Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
> ---
>  net/mptcp/pm.c           | 11 ++++++++---
>  net/mptcp/pm_netlink.c   |  9 ++++-----
>  net/mptcp/pm_userspace.c | 17 ++++++-----------
>  net/mptcp/protocol.h     |  6 ++++--
>  4 files changed, 22 insertions(+), 21 deletions(-)
> 
> diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
> index 16cacce6c10f..94620ab172b7 100644
> --- a/net/mptcp/pm.c
> +++ b/net/mptcp/pm.c
> @@ -403,20 +403,25 @@ bool mptcp_pm_rm_addr_signal(struct mptcp_sock *msk, unsigned int remaining,
>  
>  int mptcp_pm_get_local_id(struct mptcp_sock *msk, struct sock_common *skc)
>  {
> -	struct mptcp_addr_info skc_local;
> +	struct mptcp_pm_addr_entry skc_local;
>  	struct mptcp_addr_info msk_local;
>  
>  	if (WARN_ON_ONCE(!msk))
>  		return -1;
>  
> +	memset(&skc_local, 0, sizeof(struct mptcp_pm_addr_entry));

Detail: do we need memset? Can you not initialise it to 0 instead?

  struct mptcp_pm_addr_entry skc_local = { 0 };

> +
>  	/* The 0 ID mapping is defined by the first subflow, copied into the msk
>  	 * addr
>  	 */
>  	mptcp_local_address((struct sock_common *)msk, &msk_local);
> -	mptcp_local_address((struct sock_common *)skc, &skc_local);
> -	if (mptcp_addresses_equal(&msk_local, &skc_local, false))
> +	mptcp_local_address((struct sock_common *)skc, &skc_local.addr);
> +	if (mptcp_addresses_equal(&msk_local, &skc_local.addr, false))
>  		return 0;
>  
> +	skc_local.addr.id = 0;
> +	skc_local.flags = MPTCP_PM_ADDR_FLAG_IMPLICIT;
> +
>  	if (mptcp_pm_is_userspace(msk))
>  		return mptcp_userspace_pm_get_local_id(msk, &skc_local);
>  	return mptcp_pm_nl_get_local_id(msk, &skc_local);
> diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
> index d4328443d844..0a0fe890c53d 100644
> --- a/net/mptcp/pm_netlink.c
> +++ b/net/mptcp/pm_netlink.c

(...)

> @@ -1159,11 +1160,9 @@ int mptcp_pm_nl_get_local_id(struct mptcp_sock *msk, struct mptcp_addr_info *skc
>  	if (!entry)
>  		return -ENOMEM;
>  
> -	entry->addr = *skc;
> -	entry->addr.id = 0;
> +	*entry = *skc;
>  	entry->addr.port = 0;
>  	entry->ifindex = 0;
> -	entry->flags = MPTCP_PM_ADDR_FLAG_IMPLICIT;
>  	entry->lsk = NULL;
Small detail: is it still needed to reset all these info (except the
port number)?

If I'm not mistaken, now all the "entry" should be set to 0, no?

>  	ret = mptcp_pm_nl_append_new_local_addr(pernet, entry, true);
>  	if (ret < 0)
Cheers,
Matt
-- 
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