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rcu: Create a synchronize_rcu_mult()

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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
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35
include/linux/rcupdate.h
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@@ -226,6 +226,37 @@ struct rcu_synchronize {
};
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 @@ bool __rcu_is_watching(void);
* 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)