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.xin@xxxxxxxxx>
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx>
> ---
> 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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