forked from Minki/linux
486e259340
When CONFIG_RCU_FAST_NO_HZ is enabled, RCU will allow a given CPU to enter dyntick-idle mode even if it still has RCU callbacks queued. RCU avoids system hangs in this case by scheduling a timer for several jiffies in the future. However, if all of the callbacks on that CPU are from kfree_rcu(), there is no reason to wake the CPU up, as it is not a problem to defer freeing of memory. This commit therefore tracks the number of callbacks on a given CPU that are from kfree_rcu(), and avoids scheduling the timer if all of a given CPU's callbacks are from kfree_rcu(). Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
95 lines
2.8 KiB
C
95 lines
2.8 KiB
C
/*
|
|
* Read-Copy Update definitions shared among RCU implementations.
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
|
|
*
|
|
* Copyright IBM Corporation, 2011
|
|
*
|
|
* Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
|
|
*/
|
|
|
|
#ifndef __LINUX_RCU_H
|
|
#define __LINUX_RCU_H
|
|
|
|
#ifdef CONFIG_RCU_TRACE
|
|
#define RCU_TRACE(stmt) stmt
|
|
#else /* #ifdef CONFIG_RCU_TRACE */
|
|
#define RCU_TRACE(stmt)
|
|
#endif /* #else #ifdef CONFIG_RCU_TRACE */
|
|
|
|
/*
|
|
* Process-level increment to ->dynticks_nesting field. This allows for
|
|
* architectures that use half-interrupts and half-exceptions from
|
|
* process context.
|
|
*/
|
|
#define DYNTICK_TASK_NESTING (LLONG_MAX / 2 - 1)
|
|
|
|
/*
|
|
* debug_rcu_head_queue()/debug_rcu_head_unqueue() are used internally
|
|
* by call_rcu() and rcu callback execution, and are therefore not part of the
|
|
* RCU API. Leaving in rcupdate.h because they are used by all RCU flavors.
|
|
*/
|
|
|
|
#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
|
|
# define STATE_RCU_HEAD_READY 0
|
|
# define STATE_RCU_HEAD_QUEUED 1
|
|
|
|
extern struct debug_obj_descr rcuhead_debug_descr;
|
|
|
|
static inline void debug_rcu_head_queue(struct rcu_head *head)
|
|
{
|
|
WARN_ON_ONCE((unsigned long)head & 0x3);
|
|
debug_object_activate(head, &rcuhead_debug_descr);
|
|
debug_object_active_state(head, &rcuhead_debug_descr,
|
|
STATE_RCU_HEAD_READY,
|
|
STATE_RCU_HEAD_QUEUED);
|
|
}
|
|
|
|
static inline void debug_rcu_head_unqueue(struct rcu_head *head)
|
|
{
|
|
debug_object_active_state(head, &rcuhead_debug_descr,
|
|
STATE_RCU_HEAD_QUEUED,
|
|
STATE_RCU_HEAD_READY);
|
|
debug_object_deactivate(head, &rcuhead_debug_descr);
|
|
}
|
|
#else /* !CONFIG_DEBUG_OBJECTS_RCU_HEAD */
|
|
static inline void debug_rcu_head_queue(struct rcu_head *head)
|
|
{
|
|
}
|
|
|
|
static inline void debug_rcu_head_unqueue(struct rcu_head *head)
|
|
{
|
|
}
|
|
#endif /* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */
|
|
|
|
extern void kfree(const void *);
|
|
|
|
static inline bool __rcu_reclaim(char *rn, struct rcu_head *head)
|
|
{
|
|
unsigned long offset = (unsigned long)head->func;
|
|
|
|
if (__is_kfree_rcu_offset(offset)) {
|
|
RCU_TRACE(trace_rcu_invoke_kfree_callback(rn, head, offset));
|
|
kfree((void *)head - offset);
|
|
return 1;
|
|
} else {
|
|
RCU_TRACE(trace_rcu_invoke_callback(rn, head));
|
|
head->func(head);
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
#endif /* __LINUX_RCU_H */
|