staging: lustre: remove back_to_sleep()

When 'back_to_sleep()' is passed as the 'timeout' function,
the effect is to wait indefinitely for the event, polling
once after the timeout.
If LWI_ON_SIGNAL_NOOP is given, then after the timeout
we allow fatal signals to interrupt the wait.

Make this more obvious in both places "back_to_sleep()" is
used but using two explicit sleeps.

The code in ptlrpcd_add_req() looks odd - why not just have one
wait_event_idle()?  However I believe this is a faithful
transformation of the existing code.
Reviewed-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: NeilBrown <neilb@suse.com>
Reviewed-by: Patrick Farrell <paf@cray.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/include/lustre_lib.h

@@ -140,10 +140,6 @@ void target_send_reply(struct ptlrpc_request *req, int rc, int fail_id);
  * XXX nikita: some ptlrpc daemon threads have races of that sort.
  *
  */
-static inline int back_to_sleep(void *arg)
-{
-	return 0;
-}
 
 #define LWI_ON_SIGNAL_NOOP ((void (*)(void *))(-1))
 

drivers/staging/lustre/lustre/ptlrpc/import.c

@@ -1496,7 +1496,6 @@ int ptlrpc_disconnect_import(struct obd_import *imp, int noclose)
 	}
 
 	if (ptlrpc_import_in_recovery(imp)) {
-		struct l_wait_info lwi;
 		long timeout;
 
 		if (AT_OFF) {
@@ -1510,10 +1509,12 @@ int ptlrpc_disconnect_import(struct obd_import *imp, int noclose)
 			timeout = at_get(&imp->imp_at.iat_service_estimate[idx]) * HZ;
 		}
 
-		lwi = LWI_TIMEOUT_INTR(cfs_timeout_cap(timeout),
-				       back_to_sleep, LWI_ON_SIGNAL_NOOP, NULL);
-		rc = l_wait_event(imp->imp_recovery_waitq,
-				  !ptlrpc_import_in_recovery(imp), &lwi);
+		if (wait_event_idle_timeout(imp->imp_recovery_waitq,
+					    !ptlrpc_import_in_recovery(imp),
+					    cfs_timeout_cap(timeout)) == 0)
+			l_wait_event_abortable(
+				imp->imp_recovery_waitq,
+				!ptlrpc_import_in_recovery(imp));
 	}
 
 	spin_lock(&imp->imp_lock);

drivers/staging/lustre/lustre/ptlrpc/ptlrpcd.c

@@ -230,12 +230,13 @@ void ptlrpcd_add_req(struct ptlrpc_request *req)
 
 	spin_lock(&req->rq_lock);
 	if (req->rq_invalid_rqset) {
-		struct l_wait_info lwi = LWI_TIMEOUT(5 * HZ,
-						     back_to_sleep, NULL);
-
 		req->rq_invalid_rqset = 0;
 		spin_unlock(&req->rq_lock);
-		l_wait_event(req->rq_set_waitq, !req->rq_set, &lwi);
+		if (wait_event_idle_timeout(req->rq_set_waitq,
+					    !req->rq_set,
+					    5 * HZ) == 0)
+			wait_event_idle(req->rq_set_waitq,
+					!req->rq_set);
 	} else if (req->rq_set) {
 		/* If we have a valid "rq_set", just reuse it to avoid double
 		 * linked.