From: "Paul E. McKenney" <paulmck@kernel.org>
To: Wei Yang <richard.weiyang@gmail.com>
Cc: josh@joshtriplett.org, rcu@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] rcu: init and destroy rcu_synchronize when necessary
Date: Wed, 15 Apr 2020 17:24:00 -0700 [thread overview]
Message-ID: <20200416002400.GL17661@paulmck-ThinkPad-P72> (raw)
In-Reply-To: <20200415222655.9006-1-richard.weiyang@gmail.com>
On Wed, Apr 15, 2020 at 10:26:55PM +0000, Wei Yang wrote:
> We would skip the rcu_synchronize if it is a duplicate call back function.
>
> This is not necessary to init and destroy for them.
>
> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Applied, thank you!
I edited the commit log a bit. Could you please check below to make
sure that I didn't mess anything up?
Thanx, Paul
------------------------------------------------------------------------
commit d9eaddf545fe8e3e2725e2fa0bf87b59b5667c14
Author: Wei Yang <richard.weiyang@gmail.com>
Date: Wed Apr 15 22:26:55 2020 +0000
rcu: Initialize and destroy rcu_synchronize only when necessary
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@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 3ce63a9..351c322 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -391,13 +391,14 @@ 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. */
@@ -408,9 +409,10 @@ 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);
next prev parent reply other threads:[~2020-04-16 0:24 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-15 22:26 [PATCH] rcu: init and destroy rcu_synchronize when necessary Wei Yang
2020-04-16 0:24 ` Paul E. McKenney [this message]
2020-04-16 21:44 ` Wei Yang
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