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rcu_sync: Introduce rcu_sync_dtor()

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This commit allows rcu_sync structures to be safely deallocated,
The trick is to add a new ->wait field to the gp_ops array.
This field is a pointer to the rcu_barrier() function corresponding
to the flavor of RCU in question.  This allows a new rcu_sync_dtor()
to wait for any outstanding callbacks before freeing the rcu_sync
structure.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
This commit is contained in:
Oleg Nesterov 2015-08-21 19:42:52 +02:00 committed by Paul E. McKenney
parent 3a518b76af
commit 07899a6e5f
2 changed files with 27 additions and 0 deletions
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1
include/linux/rcu_sync.h
View file

@ -62,6 +62,7 @@ static inline bool rcu_sync_is_idle(struct rcu_sync *rsp)
extern void rcu_sync_init(struct rcu_sync *, enum rcu_sync_type);
extern void rcu_sync_enter(struct rcu_sync *);
extern void rcu_sync_exit(struct rcu_sync *);
extern void rcu_sync_dtor(struct rcu_sync *);
#define __RCU_SYNC_INITIALIZER(name, type) { \
.gp_state = 0, \

26
kernel/rcu/sync.c
View file

@ -32,6 +32,7 @@
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
@ -39,16 +40,19 @@ 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)
},
};
@ -195,3 +199,25 @@ void rcu_sync_exit(struct rcu_sync *rsp)
}
spin_unlock_irq(&rsp->rss_lock);
}
/**
* rcu_sync_dtor() - Clean up an rcu_sync structure
* @rsp: Pointer to rcu_sync structure to be cleaned up
*/
void rcu_sync_dtor(struct rcu_sync *rsp)
{
int cb_state;
BUG_ON(rsp->gp_count);
spin_lock_irq(&rsp->rss_lock);
if (rsp->cb_state == CB_REPLAY)
rsp->cb_state = CB_PENDING;
cb_state = rsp->cb_state;
spin_unlock_irq(&rsp->rss_lock);
if (cb_state != CB_IDLE) {
gp_ops[rsp->gp_type].wait();
BUG_ON(rsp->cb_state != CB_IDLE);
}
}