rcu: Create a synchronize_rcu_mult()

There have been several requests for a primitive that waits for
grace periods for several RCU flavors concurrently, so this
commit creates it.  This is a variadic macro, and you pass in
the call_rcu() functions of the flavors of RCU that you wish to
wait for.

Note that you cannot pass in call_srcu() for two reasons: (1) This
would result in a type mismatch and (2) You need to specify which
srcu_struct you want to use.  Handle this by creating a wrapper
function for your SRCU domain, for example:

	void call_srcu_mine(struct rcu_head *head, rcu_callback_t func)
	{
		call_srcu(&ss_mine, head, func);
	}

You can then do something like this:

	synchronize_rcu_mult(call_srcu_mine, call_rcu, call_rcu_sched);

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney 2015-06-10 12:53:06 -07:00
parent bc17ea1092
commit ec90a194ae
3 changed files with 61 additions and 14 deletions

View file

@ -318,20 +318,37 @@ void wakeme_after_rcu(struct rcu_head *head)
rcu = container_of(head, struct rcu_synchronize, head);
complete(&rcu->completion);
}
EXPORT_SYMBOL_GPL(wakeme_after_rcu);
void wait_rcu_gp(call_rcu_func_t crf)
void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array,
struct rcu_synchronize *rs_array)
{
struct rcu_synchronize rcu;
int i;
init_rcu_head_on_stack(&rcu.head);
init_completion(&rcu.completion);
/* Will wake me after RCU finished. */
crf(&rcu.head, wakeme_after_rcu);
/* Wait for it. */
wait_for_completion(&rcu.completion);
destroy_rcu_head_on_stack(&rcu.head);
/* Initialize and register callbacks for each flavor specified. */
for (i = 0; i < n; i++) {
if (checktiny &&
(crcu_array[i] == call_rcu ||
crcu_array[i] == call_rcu_bh)) {
might_sleep();
continue;
}
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. */
for (i = 0; i < n; i++) {
if (checktiny &&
(crcu_array[i] == call_rcu ||
crcu_array[i] == call_rcu_bh))
continue;
wait_for_completion(&rs_array[i].completion);
destroy_rcu_head_on_stack(&rs_array[i].head);
}
}
EXPORT_SYMBOL_GPL(wait_rcu_gp);
EXPORT_SYMBOL_GPL(__wait_rcu_gp);
#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
void init_rcu_head(struct rcu_head *head)