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Message-Id: <20200623002147.25750-1-paulmck@kernel.org>
Date: Mon, 22 Jun 2020 17:21:22 -0700
From: paulmck@...nel.org
To: rcu@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, kernel-team@...com, mingo@...nel.org,
jiangshanlai@...il.com, dipankar@...ibm.com,
akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
fweisbec@...il.com, oleg@...hat.com, joel@...lfernandes.org,
Wei Yang <richard.weiyang@...il.com>,
"Paul E . McKenney" <paulmck@...nel.org>
Subject: [PATCH tip/core/rcu 01/26] rcu: Initialize and destroy rcu_synchronize only when necessary
From: Wei Yang <richard.weiyang@...il.com>
The __wait_rcu_gp() function unconditionally initializes and cleans up
each element of rs_array[], whether used or not. This is slightly
wasteful and rather confusing, so this commit skips both initialization
and cleanup for duplicate callback functions.
Signed-off-by: Wei Yang <richard.weiyang@...il.com>
Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
---
kernel/rcu/update.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 84843ad..f5a82e1 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -390,13 +390,14 @@ void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array,
might_sleep();
continue;
}
- init_rcu_head_on_stack(&rs_array[i].head);
- init_completion(&rs_array[i].completion);
for (j = 0; j < i; j++)
if (crcu_array[j] == crcu_array[i])
break;
- if (j == i)
+ if (j == i) {
+ init_rcu_head_on_stack(&rs_array[i].head);
+ init_completion(&rs_array[i].completion);
(crcu_array[i])(&rs_array[i].head, wakeme_after_rcu);
+ }
}
/* Wait for all callbacks to be invoked. */
@@ -407,9 +408,10 @@ void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array,
for (j = 0; j < i; j++)
if (crcu_array[j] == crcu_array[i])
break;
- if (j == i)
+ if (j == i) {
wait_for_completion(&rs_array[i].completion);
- destroy_rcu_head_on_stack(&rs_array[i].head);
+ destroy_rcu_head_on_stack(&rs_array[i].head);
+ }
}
}
EXPORT_SYMBOL_GPL(__wait_rcu_gp);
--
2.9.5
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