[PATCH 03/10] SQUASH use new llist interfaces in SUNRPC: change service idle list to be an llist

[NeilBrown <neilb@xxxxxxx>]

Use init_llist_node, llist_on_list etc for checking if a node is on a
llist.
Discard svc_thread_set_busy() completely and simplify svc_thread_busy()

This can only be squashed if the patch to llist is moved earlier in the
topic.

Signed-off-by: NeilBrown <neilb@xxxxxxx>
---
 include/linux/sunrpc/svc.h | 17 ++---------------
 net/sunrpc/svc.c           |  5 ++---
 2 files changed, 4 insertions(+), 18 deletions(-)

diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index ed20a2ea1f81..ad4572630335 100644
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -266,28 +266,15 @@ enum {
 	RQ_DATA,		/* request has data */
 };
 
-/**
- * svc_thread_set_busy - mark a thread as busy
- * @rqstp: the thread which is now busy
- *
- * By convention a thread is busy if rq_idle.next points to rq_idle.
- * This will never be the case for threads on the idle list.
- */
-static inline void svc_thread_set_busy(struct svc_rqst *rqstp)
-{
-	rqstp->rq_idle.next = &rqstp->rq_idle;
-}
-
 /**
  * svc_thread_busy - check if a thread as busy
  * @rqstp: the thread which might be busy
  *
- * By convention a thread is busy if rq_idle.next points to rq_idle.
- * This will never be the case for threads on the idle list.
+ * A thread is only busy when it is not an the idle list.
  */
 static inline bool svc_thread_busy(const struct svc_rqst *rqstp)
 {
-	return rqstp->rq_idle.next == &rqstp->rq_idle;
+	return !llist_on_list(&rqstp->rq_idle);
 }
 
 #define SVC_NET(rqst) (rqst->rq_xprt ? rqst->rq_xprt->xpt_net : rqst->rq_bc_net)
diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index addbf28ea50a..5673f30db295 100644
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -642,7 +642,7 @@ svc_rqst_alloc(struct svc_serv *serv, struct svc_pool *pool, int node)
 
 	folio_batch_init(&rqstp->rq_fbatch);
 
-	svc_thread_set_busy(rqstp);
+	init_llist_node(&rqstp->rq_idle);
 	rqstp->rq_server = serv;
 	rqstp->rq_pool = pool;
 
@@ -705,11 +705,10 @@ void svc_pool_wake_idle_thread(struct svc_pool *pool)
 
 	rcu_read_lock();
 	spin_lock_bh(&pool->sp_lock);
-	ln = llist_del_first(&pool->sp_idle_threads);
+	ln = llist_del_first_init(&pool->sp_idle_threads);
 	spin_unlock_bh(&pool->sp_lock);
 	if (ln) {
 		rqstp = llist_entry(ln, struct svc_rqst, rq_idle);
-		svc_thread_set_busy(rqstp);
 
 		WRITE_ONCE(rqstp->rq_qtime, ktime_get());
 		wake_up_process(rqstp->rq_task);
-- 
2.41.0