[PATCH 01/10] SQUASH: revise comments in SUNRPC: change service idle list to be an llist

[NeilBrown <neilb@suse.de>]

Revise some comments to hopefully make the more clear and less verbose.

Signed-off-by: NeilBrown <neilb@suse.de>
---
 include/linux/sunrpc/svc.h |  6 +++---
 net/sunrpc/svc_xprt.c      | 20 +++++++-------------
 2 files changed, 10 insertions(+), 16 deletions(-)

diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index 5216f95411e3..ed20a2ea1f81 100644
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -271,7 +271,7 @@ enum {
  * @rqstp: the thread which is now busy
  *
  * By convention a thread is busy if rq_idle.next points to rq_idle.
- * This ensures it is not on the idle list.
+ * This will never be the case for threads on the idle list.
  */
 static inline void svc_thread_set_busy(struct svc_rqst *rqstp)
 {
@@ -283,9 +283,9 @@ static inline void svc_thread_set_busy(struct svc_rqst *rqstp)
  * @rqstp: the thread which might be busy
  *
  * By convention a thread is busy if rq_idle.next points to rq_idle.
- * This ensures it is not on the idle list.
+ * This will never be the case for threads on the idle list.
  */
-static inline bool svc_thread_busy(struct svc_rqst *rqstp)
+static inline bool svc_thread_busy(const struct svc_rqst *rqstp)
 {
 	return rqstp->rq_idle.next == &rqstp->rq_idle;
 }
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 81327001e074..17c43bde35c9 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -734,22 +734,16 @@ static void svc_rqst_wait_for_work(struct svc_rqst *rqstp)
 		llist_add(&rqstp->rq_idle, &pool->sp_idle_threads);
 
 		if (unlikely(!rqst_should_sleep(rqstp)))
-			/* maybe there were no idle threads when some work
-			 * became ready and so nothing was woken.  We've just
-			 * become idle so someone can to the work - maybe us.
-			 * But we cannot reliably remove ourselves from the
-			 * idle list - we can only remove the first task which
-			 * might be us, and might not.
-			 * So remove and wake it, then schedule().  If it was
-			 * us, we won't sleep.  If it is some other thread, they
-			 * will do the work.
+			/* Work just became available.  This thread cannot simply
+			 * choose not to sleep as it *must* wait until removed.
+			 * So wake the first waiter - whether it is this
+			 * thread or some other, it will get the work done.
 			 */
 			svc_pool_wake_idle_thread(pool);
 
-		/* We mustn't continue while on the idle list, and we
-		 * cannot remove outselves reliably.  The only "work"
-		 * we can do while on the idle list is to freeze.
-		 * So loop until someone removes us
+		/* Since a thread cannot remove itself from an llist,
+		 * schedule until someone else removes @rqstp from
+		 * the idle list.
 		 */
 		while (!svc_thread_busy(rqstp)) {
 			schedule();
-- 
2.41.0