Re: [PATCH RESEND mptcp-next v5 5/8] mptcp: add get_subflow wrapper

[Mat Martineau <mathew.j.martineau@linux.intel.com>]

On Thu, 24 Mar 2022, Geliang Tang wrote:

> This patch defined a new wrapper mptcp_sched_get_subflow(), invoke
> get_subflow of msk->sched in it. Use the wrapper instead of using
> mptcp_subflow_get_send() directly.
>
> Signed-off-by: Geliang Tang <geliang.tang@suse.com>
> ---
> net/mptcp/protocol.c | 6 +++---
> net/mptcp/protocol.h | 1 +
> net/mptcp/sched.c    | 7 +++++++
> 3 files changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
> index c7969b9b567e..241cfda822c0 100644
> --- a/net/mptcp/protocol.c
> +++ b/net/mptcp/protocol.c
> @@ -1567,7 +1567,7 @@ void __mptcp_push_pending(struct sock *sk, unsigned int flags)
> 			int ret = 0;
>
> 			prev_ssk = ssk;
> -			ssk = mptcp_subflow_get_send(msk);
> +			ssk = mptcp_sched_get_subflow(msk);
>
> 			/* First check. If the ssk has changed since
> 			 * the last round, release prev_ssk
> @@ -1636,7 +1636,7 @@ static void __mptcp_subflow_push_pending(struct sock *sk, struct sock *ssk)
> 			 * check for a different subflow usage only after
> 			 * spooling the first chunk of data
> 			 */
> -			xmit_ssk = first ? ssk : mptcp_subflow_get_send(mptcp_sk(sk));
> +			xmit_ssk = first ? ssk : mptcp_sched_get_subflow(mptcp_sk(sk));
> 			if (!xmit_ssk)
> 				goto out;
> 			if (xmit_ssk != ssk) {
> @@ -3134,7 +3134,7 @@ void __mptcp_check_push(struct sock *sk, struct sock *ssk)
> 		return;
>
> 	if (!sock_owned_by_user(sk)) {
> -		struct sock *xmit_ssk = mptcp_subflow_get_send(mptcp_sk(sk));
> +		struct sock *xmit_ssk = mptcp_sched_get_subflow(mptcp_sk(sk));
>
> 		if (xmit_ssk == ssk)
> 			__mptcp_subflow_push_pending(sk, ssk);
> diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
> index ad45281e8562..7781eb527b9a 100644
> --- a/net/mptcp/protocol.h
> +++ b/net/mptcp/protocol.h
> @@ -621,6 +621,7 @@ void mptcp_sched_init(void);
> void mptcp_init_sched(struct mptcp_sock *msk,
> 		      struct mptcp_sched_ops *sched);
> void mptcp_release_sched(struct mptcp_sock *msk);
> +struct sock *mptcp_sched_get_subflow(struct mptcp_sock *msk);
>
> static inline bool __mptcp_subflow_active(struct mptcp_subflow_context *subflow)
> {
> diff --git a/net/mptcp/sched.c b/net/mptcp/sched.c
> index e431b1eec5e1..2fd2a034ba49 100644
> --- a/net/mptcp/sched.c
> +++ b/net/mptcp/sched.c
> @@ -11,6 +11,7 @@
> #include <linux/list.h>
> #include <linux/rculist.h>
> #include <linux/spinlock.h>
> +#include <linux/indirect_call_wrapper.h>
> #include <net/tcp.h>
> #include <net/netns/generic.h>
> #include "protocol.h"
> @@ -143,3 +144,9 @@ void mptcp_release_sched(struct mptcp_sock *msk)
> 		msk->sched->release(msk);
> 	msk->sched = NULL;
> }
> +
> +struct sock *mptcp_sched_get_subflow(struct mptcp_sock *msk)
> +{
> +	return INDIRECT_CALL_INET_1(msk->sched->get_subflow,
> +				    mptcp_subflow_get_send, msk);
> +}

Since the purpose of this is to limit function call overhead, this could 
be implemented as a static inline function in protocol.h

--
Mat Martineau
Intel