On 09/29/2018 04:52 AM, Jon Maloy wrote:
> From: LUU Duc Canh <canh.d....@dektech.com.au>
>
> Currently, the broadcast retransmission algorithm is using the
> 'prev_retr' field in struct tipc_link to time stamp the latest broadcast
> retransmission occasion. This helps to restrict retransmission of
> individual broadcast packets to max once per 10 milliseconds, even
> though all other criteria for retransmission are met.
>
> We now move this time stamp to the control block of each individual
> packet, and remove other limiting criteria. This simplifies the
> retransmission algorithm, and eliminates any risk of logical errors
> in selecting which packets can be retransmitted.
>
> Signed-off-by: LUU Duc Canh <canh.d....@dektech.com.au>
> Signed-off-by: Jon Maloy <jon.ma...@ericsson.com>
Good approach!
Acked-by: Ying Xue <ying....@windriver.com>
> ---
> net/tipc/link.c | 49 +++++++------------------------------------------
> net/tipc/msg.h | 1 +
> 2 files changed, 8 insertions(+), 42 deletions(-)
>
> diff --git a/net/tipc/link.c b/net/tipc/link.c
> index b1f0bee..8fe5feb 100644
> --- a/net/tipc/link.c
> +++ b/net/tipc/link.c
> @@ -186,9 +186,6 @@ struct tipc_link {
> u16 acked;
> struct tipc_link *bc_rcvlink;
> struct tipc_link *bc_sndlink;
> - unsigned long prev_retr;
> - u16 prev_from;
> - u16 prev_to;
> u8 nack_state;
> bool bc_peer_is_up;
>
> @@ -210,7 +207,7 @@ enum {
> BC_NACK_SND_SUPPRESS,
> };
>
> -#define TIPC_BC_RETR_LIMIT 10 /* [ms] */
> +#define TIPC_BC_RETR_LIM msecs_to_jiffies(10) /* [ms] */
>
> /*
> * Interval between NACKs when packets arrive out of order
> @@ -1035,6 +1032,11 @@ static int tipc_link_retrans(struct tipc_link *l,
> struct tipc_link *r,
> continue;
> if (more(msg_seqno(hdr), to))
> break;
> + if (link_is_bc_sndlink(l)) {
> + if (time_before(jiffies, TIPC_SKB_CB(skb)->nxt_retr))
> + continue;
> + TIPC_SKB_CB(skb)->nxt_retr = jiffies + TIPC_BC_RETR_LIM;
> + }
> _skb = __pskb_copy(skb, MIN_H_SIZE, GFP_ATOMIC);
> if (!_skb)
> return 0;
> @@ -1679,42 +1681,6 @@ void tipc_link_bc_init_rcv(struct tipc_link *l, struct
> tipc_msg *hdr)
> l->rcv_nxt = peers_snd_nxt;
> }
>
> -/* link_bc_retr eval()- check if the indicated range can be retransmitted now
> - * - Adjust permitted range if there is overlap with previous retransmission
> - */
> -static bool link_bc_retr_eval(struct tipc_link *l, u16 *from, u16 *to)
> -{
> - unsigned long elapsed = jiffies_to_msecs(jiffies - l->prev_retr);
> -
> - if (less(*to, *from))
> - return false;
> -
> - /* New retransmission request */
> - if ((elapsed > TIPC_BC_RETR_LIMIT) ||
> - less(*to, l->prev_from) || more(*from, l->prev_to)) {
> - l->prev_from = *from;
> - l->prev_to = *to;
> - l->prev_retr = jiffies;
> - return true;
> - }
> -
> - /* Inside range of previous retransmit */
> - if (!less(*from, l->prev_from) && !more(*to, l->prev_to))
> - return false;
> -
> - /* Fully or partially outside previous range => exclude overlap */
> - if (less(*from, l->prev_from)) {
> - *to = l->prev_from - 1;
> - l->prev_from = *from;
> - }
> - if (more(*to, l->prev_to)) {
> - *from = l->prev_to + 1;
> - l->prev_to = *to;
> - }
> - l->prev_retr = jiffies;
> - return true;
> -}
> -
> /* tipc_link_bc_sync_rcv - update rcv link according to peer's send state
> */
> int tipc_link_bc_sync_rcv(struct tipc_link *l, struct tipc_msg *hdr,
> @@ -1745,8 +1711,7 @@ int tipc_link_bc_sync_rcv(struct tipc_link *l, struct
> tipc_msg *hdr,
> if (more(peers_snd_nxt, l->rcv_nxt + l->window))
> return rc;
>
> - if (link_bc_retr_eval(snd_l, &from, &to))
> - rc = tipc_link_retrans(snd_l, l, from, to, xmitq);
> + rc = tipc_link_retrans(snd_l, l, from, to, xmitq);
>
> l->snd_nxt = peers_snd_nxt;
> if (link_bc_rcv_gap(l))
> diff --git a/net/tipc/msg.h b/net/tipc/msg.h
> index a2879e6..a092495 100644
> --- a/net/tipc/msg.h
> +++ b/net/tipc/msg.h
> @@ -105,6 +105,7 @@ struct tipc_skb_cb {
> u32 bytes_read;
> u32 orig_member;
> struct sk_buff *tail;
> + unsigned long nxt_retr;
> bool validated;
> u16 chain_imp;
> u16 ackers;
>
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