From 1bb5f9b95afe5d9d6b586389ce5e8f461a5b671c Mon Sep 17 00:00:00 2001
From: "Paul E. McKenney" <paulmck@linux.ibm.com>
Date: Fri, 12 Apr 2019 12:34:41 -0700
Subject: rcu/nocb: Use separate flag to indicate disabled ->cblist
NULLing the RCU_NEXT_TAIL pointer was a clever way to save a byte, but
forward-progress considerations would require that this pointer be both
NULL and non-NULL, which, absent a quantum-computer port of the Linux
kernel, simply won't happen. This commit therefore creates as separate
->enabled flag to replace the current NULL checks.
[ paulmck: Add include files per 0day test robot and -next. ]
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
---
kernel/rcu/rcu_segcblist.c | 3 ++-
kernel/rcu/rcu_segcblist.h | 2 +-
kernel/rcu/tree_plugin.h | 2 +-
3 files changed, 4 insertions(+), 3 deletions(-)
(limited to 'kernel/rcu')
diff --git a/kernel/rcu/rcu_segcblist.c b/kernel/rcu/rcu_segcblist.c
index 9bd5f6023c21..b305dcac34c9 100644
--- a/kernel/rcu/rcu_segcblist.c
+++ b/kernel/rcu/rcu_segcblist.c
@@ -58,6 +58,7 @@ void rcu_segcblist_init(struct rcu_segcblist *rsclp)
rsclp->tails[i] = &rsclp->head;
rsclp->len = 0;
rsclp->len_lazy = 0;
+ rsclp->enabled = 1;
}
/*
@@ -69,7 +70,7 @@ void rcu_segcblist_disable(struct rcu_segcblist *rsclp)
WARN_ON_ONCE(!rcu_segcblist_empty(rsclp));
WARN_ON_ONCE(rcu_segcblist_n_cbs(rsclp));
WARN_ON_ONCE(rcu_segcblist_n_lazy_cbs(rsclp));
- rsclp->tails[RCU_NEXT_TAIL] = NULL;
+ rsclp->enabled = 0;
}
/*
diff --git a/kernel/rcu/rcu_segcblist.h b/kernel/rcu/rcu_segcblist.h
index 822a39da0533..b2de7b32da29 100644
--- a/kernel/rcu/rcu_segcblist.h
+++ b/kernel/rcu/rcu_segcblist.h
@@ -63,7 +63,7 @@ static inline long rcu_segcblist_n_nonlazy_cbs(struct rcu_segcblist *rsclp)
*/
static inline bool rcu_segcblist_is_enabled(struct rcu_segcblist *rsclp)
{
- return !!rsclp->tails[RCU_NEXT_TAIL];
+ return rsclp->enabled;
}
/*
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 0a3f8680b450..b8a43cf9bb4e 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -2189,8 +2189,8 @@ static bool init_nocb_callback_list(struct rcu_data *rdp)
rcu_segcblist_n_cbs(&rdp->cblist));
atomic_long_set(&rdp->nocb_q_count_lazy,
rcu_segcblist_n_lazy_cbs(&rdp->cblist));
- rcu_segcblist_init(&rdp->cblist);
}
+ rcu_segcblist_init(&rdp->cblist);
rcu_segcblist_disable(&rdp->cblist);
return true;
}
--
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