sctp: make the raise timer more simple and accurate

Currently, the probe timer is reused as the raise timer when PLPMTUD is in
the Search Complete state. raise_count was introduced to count how many
times the probe timer has timed out. When raise_count reaches to 30, the
raise timer handler will be triggered.

During the whole processing above, the timer keeps timing out every probe_
interval. It is a waste for the Search Complete state, as the raise timer
only needs to time out after 30 * probe_interval.

Since the raise timer and probe timer are never used at the same time, it
is no need to keep probe timer 'alive' in the Search Complete state. This
patch to introduce sctp_transport_reset_raise_timer() to start the timer
as the raise timer when entering the Search Complete state. When entering
the other states, sctp_transport_reset_probe_timer() will still be called
to reset the timer to the probe timer.

raise_count can be removed from sctp_transport as no need to count probe
timer timeout for raise timer timeout. last_rtx_chunks can be removed as
sctp_transport_reset_probe_timer() can be called in the place where asoc
rtx_data_chunks is changed.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Link: https://lore.kernel.org/r/edb0e48988ea85997488478b705b11ddc1ba724a.1637781974.git.lucien.xin@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 3 insertions, 4 deletions

diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index 899c29c326ba..e7d1ed7a3dfb 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -984,12 +984,10 @@ struct sctp_transport {
 	} cacc;
 
 	struct {
-		__u32 last_rtx_chunks;
 		__u16 pmtu;
 		__u16 probe_size;
 		__u16 probe_high;
-		__u8 probe_count:3;
-		__u8 raise_count:5;
+		__u8 probe_count;
 		__u8 state;
 	} pl; /* plpmtud related */
 
@@ -1011,6 +1009,7 @@ void sctp_transport_reset_t3_rtx(struct sctp_transport *);
 void sctp_transport_reset_hb_timer(struct sctp_transport *);
 void sctp_transport_reset_reconf_timer(struct sctp_transport *transport);
 void sctp_transport_reset_probe_timer(struct sctp_transport *transport);
+void sctp_transport_reset_raise_timer(struct sctp_transport *transport);
 int sctp_transport_hold(struct sctp_transport *);
 void sctp_transport_put(struct sctp_transport *);
 void sctp_transport_update_rto(struct sctp_transport *, __u32);
@@ -1025,7 +1024,7 @@ bool sctp_transport_update_pmtu(struct sctp_transport *t, u32 pmtu);
 void sctp_transport_immediate_rtx(struct sctp_transport *);
 void sctp_transport_dst_release(struct sctp_transport *t);
 void sctp_transport_dst_confirm(struct sctp_transport *t);
-bool sctp_transport_pl_send(struct sctp_transport *t);
+void sctp_transport_pl_send(struct sctp_transport *t);
 bool sctp_transport_pl_recv(struct sctp_transport *t);