[openib-general] [PATCH] sdp_inet: fix schedule_timeout() usage

[Libor Michalek]

On Tue, Jun 28, 2005 at 01:48:55PM -0700, Nishanth Aravamudan wrote:
>
> Using schedule_timeout() without setting the state first is broken and
> causes schedule_timeout() to return immediately (effectively you call
> schedule() without changing your state and are thus going to run again).
> In each of these loops in sdp_inet.c involving schedule_timeout(), the
> first iteration is correct, but subsequent ones result in busy-wait. Add
> the appropriate set_current_state() call to fix the issue.

Nish,

  Thank you for the patch. I'm wondering if it would be better to just
move the existing call to set_current_state(TASK_INTERRUPTIBLE) from
outside the loop to inside at the begining, as below?

-Libor

Index: sdp_inet.c
===================================================================
--- sdp_inet.c	(revision 2749)
+++ sdp_inet.c	(working copy)
@@ -317,10 +317,11 @@
 			timeout = sk->sk_lingertime;
 			
 			add_wait_queue(sk->sk_sleep, &wait);
-			set_current_state(TASK_INTERRUPTIBLE);
 
 			while (timeout > 0 &&
 			       !(SDP_ST_MASK_CLOSED & conn->state)) {
+
+				set_current_state(TASK_INTERRUPTIBLE);
 				sdp_conn_unlock(conn);
 				timeout = schedule_timeout(timeout);
 				sdp_conn_lock(conn);
@@ -554,10 +555,10 @@
 
 		DECLARE_WAITQUEUE(wait, current);
 		add_wait_queue(sk->sk_sleep, &wait);
-		set_current_state(TASK_INTERRUPTIBLE);
 
 		while (timeout > 0 && (conn->state & SDP_ST_MASK_CONNECT)) {
 
+			set_current_state(TASK_INTERRUPTIBLE);
 			sdp_conn_unlock(conn);
 			timeout = schedule_timeout(timeout);
 			sdp_conn_lock(conn);
@@ -710,11 +711,12 @@
 		if (!accept_conn) {
 			DECLARE_WAITQUEUE(wait, current);
 			add_wait_queue(listen_sk->sk_sleep, &wait);
-			set_current_state(TASK_INTERRUPTIBLE);
 
 			while (timeout > 0 &&
 			       listen_conn->state == SDP_CONN_ST_LISTEN &&
 			       !listen_conn->backlog_cnt) {
+
+				set_current_state(TASK_INTERRUPTIBLE);
 				sdp_conn_unlock(listen_conn);
 				timeout = schedule_timeout(timeout);
 				sdp_conn_lock(listen_conn);