Re: [PATCH net-next 1/2] sctp: implement memory accounting on tx path

[Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>]

On Sun, Mar 31, 2019 at 04:53:46PM +0800, Xin Long wrote:
> Now when sending packets, sk_mem_charge() and sk_mem_uncharge() have been
> used to set sk_forward_alloc. We just need to call sk_wmem_schedule() to
> check if the allocated should be raised, and call sk_mem_reclaim() to
> check if the allocated should be reduced when it's under memory pressure.
> 
> If sk_wmem_schedule() returns false, which means no memory is allowed to
> allocate, it will block and wait for memory to become available.
> 
> Note different from tcp, sctp wait_for_buf happens before allocating any
> skb, so memory accounting check is done with the whole msg_len before it
> too.
> 
> Signed-off-by: Xin Long <lucien.xin@gmail.com>

Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>

> ---
>  net/sctp/socket.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> index 6140471..06c6f4a 100644
> --- a/net/sctp/socket.c
> +++ b/net/sctp/socket.c
> @@ -1913,7 +1913,10 @@ static int sctp_sendmsg_to_asoc(struct sctp_association *asoc,
>  	if (sctp_wspace(asoc) < (int)msg_len)
>  		sctp_prsctp_prune(asoc, sinfo, msg_len - sctp_wspace(asoc));
>  
> -	if (sctp_wspace(asoc) <= 0) {
> +	if (sk_under_memory_pressure(sk))
> +		sk_mem_reclaim(sk);
> +
> +	if (sctp_wspace(asoc) <= 0 || !sk_wmem_schedule(sk, msg_len)) {
>  		timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
>  		err = sctp_wait_for_sndbuf(asoc, &timeo, msg_len);
>  		if (err)
> @@ -8891,7 +8894,10 @@ static int sctp_wait_for_sndbuf(struct sctp_association *asoc, long *timeo_p,
>  			goto do_error;
>  		if (signal_pending(current))
>  			goto do_interrupted;
> -		if ((int)msg_len <= sctp_wspace(asoc))
> +		if (sk_under_memory_pressure(sk))
> +			sk_mem_reclaim(sk);
> +		if ((int)msg_len <= sctp_wspace(asoc) &&
> +		    sk_wmem_schedule(sk, msg_len))
>  			break;
>  
>  		/* Let another process have a go.  Since we are going
> -- 
> 2.1.0
>