From d22959aa93528c6cf4583560696856cf6bba6b72 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 2 Feb 2022 09:10:04 -0800 Subject: [PATCH] rcu: Clarify fill-the-gap comment in rcu_segcblist_advance() Reported-by: Frederic Weisbecker Reported-by: Neeraj Upadhyay Reported-by: Boqun Feng Signed-off-by: Paul E. McKenney --- kernel/rcu/rcu_segcblist.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/kernel/rcu/rcu_segcblist.c b/kernel/rcu/rcu_segcblist.c index 81145c3ece25..c54ea2b6a36b 100644 --- a/kernel/rcu/rcu_segcblist.c +++ b/kernel/rcu/rcu_segcblist.c @@ -505,10 +505,10 @@ void rcu_segcblist_advance(struct rcu_segcblist *rsclp, unsigned long seq) WRITE_ONCE(rsclp->tails[j], rsclp->tails[RCU_DONE_TAIL]); /* - * Callbacks moved, so clean up the misordered ->tails[] pointers - * that now point into the middle of the list of ready-to-invoke - * callbacks. The overall effect is to copy down the later pointers - * into the gap that was created by the now-ready segments. + * Callbacks moved, so there might be an empty RCU_WAIT_TAIL + * and a non-empty RCU_NEXT_READY_TAIL. If so, copy the + * RCU_NEXT_READY_TAIL segment to fill the RCU_WAIT_TAIL gap + * created by the now-ready-to-invoke segments. */ for (j = RCU_WAIT_TAIL; i < RCU_NEXT_TAIL; i++, j++) { if (rsclp->tails[j] == rsclp->tails[RCU_NEXT_TAIL])