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>
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index c63428c..33ec16b 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -226,6 +226,37 @@
};
void wakeme_after_rcu(struct rcu_head *head);
+void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array,
+ struct rcu_synchronize *rs_array);
+
+#define _wait_rcu_gp(checktiny, ...) \
+do { \
+ call_rcu_func_t __crcu_array[] = { __VA_ARGS__ }; \
+ const int __n = ARRAY_SIZE(__crcu_array); \
+ struct rcu_synchronize __rs_array[__n]; \
+ \
+ __wait_rcu_gp(checktiny, __n, __crcu_array, __rs_array); \
+} while (0)
+
+#define wait_rcu_gp(...) _wait_rcu_gp(false, __VA_ARGS__)
+
+/**
+ * synchronize_rcu_mult - Wait concurrently for multiple grace periods
+ * @...: List of call_rcu() functions for the flavors to wait on.
+ *
+ * This macro waits concurrently for multiple flavors of RCU grace periods.
+ * For example, synchronize_rcu_mult(call_rcu, call_rcu_bh) would wait
+ * on concurrent RCU and RCU-bh grace periods. Waiting on a give SRCU
+ * domain requires you to write a wrapper function for that SRCU domain's
+ * call_srcu() function, supplying the corresponding srcu_struct.
+ *
+ * If Tiny RCU, tell _wait_rcu_gp() not to bother waiting for RCU
+ * or RCU-bh, given that anywhere synchronize_rcu_mult() can be called
+ * is automatically a grace period.
+ */
+#define synchronize_rcu_mult(...) \
+ _wait_rcu_gp(IS_ENABLED(CONFIG_TINY_RCU), __VA_ARGS__)
+
/**
* call_rcu_tasks() - Queue an RCU for invocation task-based grace period
* @head: structure to be used for queueing the RCU updates.
@@ -392,10 +423,6 @@
* TREE_RCU and rcu_barrier_() primitives in TINY_RCU.
*/
-typedef void call_rcu_func_t(struct rcu_head *head,
- void (*func)(struct rcu_head *head));
-void wait_rcu_gp(call_rcu_func_t crf);
-
#if defined(CONFIG_TREE_RCU) || defined(CONFIG_PREEMPT_RCU)
#include <linux/rcutree.h>
#elif defined(CONFIG_TINY_RCU)