On Wed, Apr 15, 2020 at 05:24:00PM -0700, Paul E. McKenney wrote:
>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@xxxxxxxxx>
>
>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?
>
Yep, the changelog looks good to me :-)
Glad you like it.
> Thanx, Paul
>
>------------------------------------------------------------------------
>
>commit d9eaddf545fe8e3e2725e2fa0bf87b59b5667c14
>Author: Wei Yang <richard.weiyang@xxxxxxxxx>
>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@xxxxxxxxx>
> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
>
>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);
--
Wei Yang
Help you, Help me
