cba6d0d64e
This reverts commit 616c310e83.
(Move PREEMPT_RCU preemption to switch_to() invocation).
Testing by Sasha Levin <levinsasha928@gmail.com> showed that this
can result in deadlock due to invoking the scheduler when one of
the runqueue locks is held. Because this commit was simply a
performance optimization, revert it.
Reported-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Sasha Levin <levinsasha928@gmail.com>
168 lines
3.5 KiB
C
168 lines
3.5 KiB
C
/*
|
|
* Read-Copy Update mechanism for mutual exclusion, the Bloatwatch edition.
|
|
*
|
|
* 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, 2008
|
|
*
|
|
* Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
|
|
*
|
|
* For detailed explanation of Read-Copy Update mechanism see -
|
|
* Documentation/RCU
|
|
*/
|
|
#ifndef __LINUX_TINY_H
|
|
#define __LINUX_TINY_H
|
|
|
|
#include <linux/cache.h>
|
|
|
|
static inline void rcu_init(void)
|
|
{
|
|
}
|
|
|
|
static inline void rcu_barrier_bh(void)
|
|
{
|
|
wait_rcu_gp(call_rcu_bh);
|
|
}
|
|
|
|
static inline void rcu_barrier_sched(void)
|
|
{
|
|
wait_rcu_gp(call_rcu_sched);
|
|
}
|
|
|
|
#ifdef CONFIG_TINY_RCU
|
|
|
|
static inline void synchronize_rcu_expedited(void)
|
|
{
|
|
synchronize_sched(); /* Only one CPU, so pretty fast anyway!!! */
|
|
}
|
|
|
|
static inline void rcu_barrier(void)
|
|
{
|
|
rcu_barrier_sched(); /* Only one CPU, so only one list of callbacks! */
|
|
}
|
|
|
|
#else /* #ifdef CONFIG_TINY_RCU */
|
|
|
|
void synchronize_rcu_expedited(void);
|
|
|
|
static inline void rcu_barrier(void)
|
|
{
|
|
wait_rcu_gp(call_rcu);
|
|
}
|
|
|
|
#endif /* #else #ifdef CONFIG_TINY_RCU */
|
|
|
|
static inline void synchronize_rcu_bh(void)
|
|
{
|
|
synchronize_sched();
|
|
}
|
|
|
|
static inline void synchronize_rcu_bh_expedited(void)
|
|
{
|
|
synchronize_sched();
|
|
}
|
|
|
|
static inline void synchronize_sched_expedited(void)
|
|
{
|
|
synchronize_sched();
|
|
}
|
|
|
|
static inline void kfree_call_rcu(struct rcu_head *head,
|
|
void (*func)(struct rcu_head *rcu))
|
|
{
|
|
call_rcu(head, func);
|
|
}
|
|
|
|
#ifdef CONFIG_TINY_RCU
|
|
|
|
static inline void rcu_preempt_note_context_switch(void)
|
|
{
|
|
}
|
|
|
|
static inline int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies)
|
|
{
|
|
*delta_jiffies = ULONG_MAX;
|
|
return 0;
|
|
}
|
|
|
|
#else /* #ifdef CONFIG_TINY_RCU */
|
|
|
|
void rcu_preempt_note_context_switch(void);
|
|
int rcu_preempt_needs_cpu(void);
|
|
|
|
static inline int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies)
|
|
{
|
|
*delta_jiffies = ULONG_MAX;
|
|
return rcu_preempt_needs_cpu();
|
|
}
|
|
|
|
#endif /* #else #ifdef CONFIG_TINY_RCU */
|
|
|
|
static inline void rcu_note_context_switch(int cpu)
|
|
{
|
|
rcu_sched_qs(cpu);
|
|
rcu_preempt_note_context_switch();
|
|
}
|
|
|
|
/*
|
|
* Take advantage of the fact that there is only one CPU, which
|
|
* allows us to ignore virtualization-based context switches.
|
|
*/
|
|
static inline void rcu_virt_note_context_switch(int cpu)
|
|
{
|
|
}
|
|
|
|
/*
|
|
* Return the number of grace periods.
|
|
*/
|
|
static inline long rcu_batches_completed(void)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Return the number of bottom-half grace periods.
|
|
*/
|
|
static inline long rcu_batches_completed_bh(void)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static inline void rcu_force_quiescent_state(void)
|
|
{
|
|
}
|
|
|
|
static inline void rcu_bh_force_quiescent_state(void)
|
|
{
|
|
}
|
|
|
|
static inline void rcu_sched_force_quiescent_state(void)
|
|
{
|
|
}
|
|
|
|
static inline void rcu_cpu_stall_reset(void)
|
|
{
|
|
}
|
|
|
|
#ifdef CONFIG_DEBUG_LOCK_ALLOC
|
|
extern int rcu_scheduler_active __read_mostly;
|
|
extern void rcu_scheduler_starting(void);
|
|
#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
|
|
static inline void rcu_scheduler_starting(void)
|
|
{
|
|
}
|
|
#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
|
|
|
|
#endif /* __LINUX_RCUTINY_H */
|