sctp: do not check hb_timer.expires when resetting hb_timer

It tries to avoid the frequently hb_timer refresh in commit ba6f5e33bdbb
("sctp: avoid refreshing heartbeat timer too often"), and it only allows
mod_timer when the new expires is after hb_timer.expires. It means even
a much shorter interval for hb timer gets applied, it will have to wait
until the current hb timer to time out.

In sctp_do_8_2_transport_strike(), when a transport enters PF state, it
expects to update the hb timer to resend a heartbeat every rto after
calling sctp_transport_reset_hb_timer(), which will not work as the
change mentioned above.

The frequently hb_timer refresh was caused by sctp_transport_reset_timers()
called in sctp_outq_flush() and it was already removed in the commit above.
So we don't have to check hb_timer.expires when resetting hb_timer as it is
now not called very often.

Fixes: ba6f5e33bdbb ("sctp: avoid refreshing heartbeat timer too often")
Signed-off-by: Xin Long <[e-mail]>
Acked-by: Marcelo Ricardo Leitner <[e-mail]>
Link: https://lore.kernel.org/r/d9[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

net/sctp/transport.c

···
 
 	/* When a data chunk is sent, reset the heartbeat interval.  */
 	expires = jiffies + sctp_transport_timeout(transport);
-	if ((time_before(transport->hb_timer.expires, expires) ||
-	     !timer_pending(&transport->hb_timer)) &&
-	    !mod_timer(&transport->hb_timer,
+	if (!mod_timer(&transport->hb_timer,
 		       expires + get_random_u32_below(transport->rto)))
 		sctp_transport_hold(transport);
 }