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SubjectRe: [PATCH 6/6] rcusync: Introduce rcu_sync_dtor()
On Tue, Oct 08, 2013 at 12:25:11PM +0200, Peter Zijlstra wrote:
> From: Oleg Nesterov <oleg@redhat.com>
>
> Add the new rcu_sync_ops->wait() method and the new helper,
> rcu_sync_dtor().
>
> It is needed if you are going to, say, kfree(rcu_sync_object).
> It simply calls ops->wait() to "flush" the potentially pending
> rcu callback.
>
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
> Signed-off-by: Peter Zijlstra <peterz@infradead.org>

Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

> Link: http://lkml.kernel.org/r/20131004184636.GA17560@redhat.com
> ---
> include/linux/rcusync.h | 1 +
> kernel/rcusync.c | 22 ++++++++++++++++++++++
> 2 files changed, 23 insertions(+)
>
> --- a/include/linux/rcusync.h
> +++ b/include/linux/rcusync.h
> @@ -31,6 +31,7 @@ static inline bool rcu_sync_is_idle(stru
> extern void rcu_sync_init(struct rcu_sync_struct *, enum rcu_sync_type);
> extern void rcu_sync_enter(struct rcu_sync_struct *);
> extern void rcu_sync_exit(struct rcu_sync_struct *);
> +extern void rcu_sync_dtor(struct rcu_sync_struct *);
>
> #define __RCU_SYNC_INITIALIZER(name, type) { \
> .gp_state = 0, \
> --- a/kernel/rcusync.c
> +++ b/kernel/rcusync.c
> @@ -10,6 +10,7 @@
> static const struct {
> void (*sync)(void);
> void (*call)(struct rcu_head *, void (*)(struct rcu_head *));
> + void (*wait)(void);
> #ifdef CONFIG_PROVE_RCU
> int (*held)(void);
> #endif
> @@ -17,16 +18,19 @@ static const struct {
> [RCU_SYNC] = {
> .sync = synchronize_rcu,
> .call = call_rcu,
> + .wait = rcu_barrier,
> __INIT_HELD(rcu_read_lock_held)
> },
> [RCU_SCHED_SYNC] = {
> .sync = synchronize_sched,
> .call = call_rcu_sched,
> + .wait = rcu_barrier_sched,
> __INIT_HELD(rcu_read_lock_sched_held)
> },
> [RCU_BH_SYNC] = {
> .sync = synchronize_rcu_bh,
> .call = call_rcu_bh,
> + .wait = rcu_barrier_bh,
> __INIT_HELD(rcu_read_lock_bh_held)
> },
> };
> @@ -128,3 +132,21 @@ void rcu_sync_exit(struct rcu_sync_struc
> }
> spin_unlock_irq(&rss->rss_lock);
> }
> +
> +void rcu_sync_dtor(struct rcu_sync_struct *rss)
> +{
> + int cb_state;
> +
> + BUG_ON(rss->gp_count);
> +
> + spin_lock_irq(&rss->rss_lock);
> + if (rss->cb_state == CB_REPLAY)
> + rss->cb_state = CB_PENDING;
> + cb_state = rss->cb_state;
> + spin_unlock_irq(&rss->rss_lock);
> +
> + if (cb_state != CB_IDLE) {
> + gp_ops[rss->gp_type].wait();
> + BUG_ON(rss->cb_state != CB_IDLE);
> + }
> +}
>
>



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