On Fri, Jan 22, 2016 at 01:49:09AM +0800, Xin Long wrote:
> After we use refcnt to check if transport is alive, the dead can be
> removed from sctp_transport.
> 
> The traversal of transport_addr_list in procfs dump is using
> list_for_each_entry_rcu, no need to check if it has been freed.
> 
> sctp_generate_t3_rtx_event and sctp_generate_heartbeat_event is
> protected by sock lock, it's not necessary to check dead, either.
> also, the timers are cancelled when sctp_transport_free() is
> called, that it doesn't wait for refcnt to reach 0 to cancel them.
> 
> Signed-off-by: Xin Long <lucien....@gmail.com>

Signed-off-by: Marcelo Ricardo Leitner <marcelo.leit...@gmail.com>

> ---
>  include/net/sctp/structs.h |  3 +--
>  net/sctp/proc.c            |  4 ----
>  net/sctp/sm_sideeffect.c   | 12 ------------
>  net/sctp/transport.c       |  4 +---
>  4 files changed, 2 insertions(+), 21 deletions(-)
> 
> diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
> index 344da04..205630b 100644
> --- a/include/net/sctp/structs.h
> +++ b/include/net/sctp/structs.h
> @@ -756,7 +756,6 @@ struct sctp_transport {
>  
>       /* Reference counting. */
>       atomic_t refcnt;
> -     __u32    dead:1,
>               /* RTO-Pending : A flag used to track if one of the DATA
>                *              chunks sent to this address is currently being
>                *              used to compute a RTT. If this flag is 0,
> @@ -766,7 +765,7 @@ struct sctp_transport {
>                *              calculation completes (i.e. the DATA chunk
>                *              is SACK'd) clear this flag.
>                */
> -              rto_pending:1,
> +     __u32   rto_pending:1,
>  
>               /*
>                * hb_sent : a flag that signals that we have a pending
> diff --git a/net/sctp/proc.c b/net/sctp/proc.c
> index c74a810..ded7d93 100644
> --- a/net/sctp/proc.c
> +++ b/net/sctp/proc.c
> @@ -165,8 +165,6 @@ static void sctp_seq_dump_remote_addrs(struct seq_file 
> *seq, struct sctp_associa
>       list_for_each_entry_rcu(transport, &assoc->peer.transport_addr_list,
>                       transports) {
>               addr = &transport->ipaddr;
> -             if (transport->dead)
> -                     continue;
>  
>               af = sctp_get_af_specific(addr->sa.sa_family);
>               if (af->cmp_addr(addr, primary)) {
> @@ -499,8 +497,6 @@ static int sctp_remaddr_seq_show(struct seq_file *seq, 
> void *v)
>  
>       list_for_each_entry_rcu(tsp, &assoc->peer.transport_addr_list,
>                               transports) {
> -             if (tsp->dead)
> -                     continue;
>               /*
>                * The remote address (ADDR)
>                */
> diff --git a/net/sctp/sm_sideeffect.c b/net/sctp/sm_sideeffect.c
> index 2e21384..b5327bb 100644
> --- a/net/sctp/sm_sideeffect.c
> +++ b/net/sctp/sm_sideeffect.c
> @@ -259,12 +259,6 @@ void sctp_generate_t3_rtx_event(unsigned long peer)
>               goto out_unlock;
>       }
>  
> -     /* Is this transport really dead and just waiting around for
> -      * the timer to let go of the reference?
> -      */
> -     if (transport->dead)
> -             goto out_unlock;
> -
>       /* Run through the state machine.  */
>       error = sctp_do_sm(net, SCTP_EVENT_T_TIMEOUT,
>                          SCTP_ST_TIMEOUT(SCTP_EVENT_TIMEOUT_T3_RTX),
> @@ -380,12 +374,6 @@ void sctp_generate_heartbeat_event(unsigned long data)
>               goto out_unlock;
>       }
>  
> -     /* Is this structure just waiting around for us to actually
> -      * get destroyed?
> -      */
> -     if (transport->dead)
> -             goto out_unlock;
> -
>       error = sctp_do_sm(net, SCTP_EVENT_T_TIMEOUT,
>                          SCTP_ST_TIMEOUT(SCTP_EVENT_TIMEOUT_HEARTBEAT),
>                          asoc->state, asoc->ep, asoc,
> diff --git a/net/sctp/transport.c b/net/sctp/transport.c
> index 69f3799..a431c14 100644
> --- a/net/sctp/transport.c
> +++ b/net/sctp/transport.c
> @@ -132,8 +132,6 @@ fail:
>   */
>  void sctp_transport_free(struct sctp_transport *transport)
>  {
> -     transport->dead = 1;
> -
>       /* Try to delete the heartbeat timer.  */
>       if (del_timer(&transport->hb_timer))
>               sctp_transport_put(transport);
> @@ -169,7 +167,7 @@ static void sctp_transport_destroy_rcu(struct rcu_head 
> *head)
>   */
>  static void sctp_transport_destroy(struct sctp_transport *transport)
>  {
> -     if (unlikely(!transport->dead)) {
> +     if (unlikely(atomic_read(&transport->refcnt))) {
>               WARN(1, "Attempt to destroy undead transport %p!\n", transport);
>               return;
>       }
> -- 
> 2.1.0
> 
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