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>
This commit is contained in:
Wei Yang 2020-04-15 22:26:55 +00:00 committed by Paul E. McKenney
parent 9ebcfadb06
commit 7ee880b7bf

View File

@ -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);