2d3d891d33
Some method to deal with rt-mutexes and make sched_dl interact with the current PI-coded is needed, raising all but trivial issues, that needs (according to us) to be solved with some restructuring of the pi-code (i.e., going toward a proxy execution-ish implementation). This is under development, in the meanwhile, as a temporary solution, what this commits does is: - ensure a pi-lock owner with waiters is never throttled down. Instead, when it runs out of runtime, it immediately gets replenished and it's deadline is postponed; - the scheduling parameters (relative deadline and default runtime) used for that replenishments --during the whole period it holds the pi-lock-- are the ones of the waiting task with earliest deadline. Acting this way, we provide some kind of boosting to the lock-owner, still by using the existing (actually, slightly modified by the previous commit) pi-architecture. We would stress the fact that this is only a surely needed, all but clean solution to the problem. In the end it's only a way to re-start discussion within the community. So, as always, comments, ideas, rants, etc.. are welcome! :-) Signed-off-by: Dario Faggioli <raistlin@linux.it> Signed-off-by: Juri Lelli <juri.lelli@gmail.com> [ Added !RT_MUTEXES build fix. ] Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1383831828-15501-11-git-send-email-juri.lelli@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
127 lines
3.3 KiB
C
127 lines
3.3 KiB
C
/*
|
|
* RT Mutexes: blocking mutual exclusion locks with PI support
|
|
*
|
|
* started by Ingo Molnar and Thomas Gleixner:
|
|
*
|
|
* Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
|
|
* Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
|
|
*
|
|
* This file contains the private data structure and API definitions.
|
|
*/
|
|
|
|
#ifndef __KERNEL_RTMUTEX_COMMON_H
|
|
#define __KERNEL_RTMUTEX_COMMON_H
|
|
|
|
#include <linux/rtmutex.h>
|
|
|
|
/*
|
|
* The rtmutex in kernel tester is independent of rtmutex debugging. We
|
|
* call schedule_rt_mutex_test() instead of schedule() for the tasks which
|
|
* belong to the tester. That way we can delay the wakeup path of those
|
|
* threads to provoke lock stealing and testing of complex boosting scenarios.
|
|
*/
|
|
#ifdef CONFIG_RT_MUTEX_TESTER
|
|
|
|
extern void schedule_rt_mutex_test(struct rt_mutex *lock);
|
|
|
|
#define schedule_rt_mutex(_lock) \
|
|
do { \
|
|
if (!(current->flags & PF_MUTEX_TESTER)) \
|
|
schedule(); \
|
|
else \
|
|
schedule_rt_mutex_test(_lock); \
|
|
} while (0)
|
|
|
|
#else
|
|
# define schedule_rt_mutex(_lock) schedule()
|
|
#endif
|
|
|
|
/*
|
|
* This is the control structure for tasks blocked on a rt_mutex,
|
|
* which is allocated on the kernel stack on of the blocked task.
|
|
*
|
|
* @tree_entry: pi node to enqueue into the mutex waiters tree
|
|
* @pi_tree_entry: pi node to enqueue into the mutex owner waiters tree
|
|
* @task: task reference to the blocked task
|
|
*/
|
|
struct rt_mutex_waiter {
|
|
struct rb_node tree_entry;
|
|
struct rb_node pi_tree_entry;
|
|
struct task_struct *task;
|
|
struct rt_mutex *lock;
|
|
#ifdef CONFIG_DEBUG_RT_MUTEXES
|
|
unsigned long ip;
|
|
struct pid *deadlock_task_pid;
|
|
struct rt_mutex *deadlock_lock;
|
|
#endif
|
|
int prio;
|
|
};
|
|
|
|
/*
|
|
* Various helpers to access the waiters-tree:
|
|
*/
|
|
static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
|
|
{
|
|
return !RB_EMPTY_ROOT(&lock->waiters);
|
|
}
|
|
|
|
static inline struct rt_mutex_waiter *
|
|
rt_mutex_top_waiter(struct rt_mutex *lock)
|
|
{
|
|
struct rt_mutex_waiter *w;
|
|
|
|
w = rb_entry(lock->waiters_leftmost, struct rt_mutex_waiter,
|
|
tree_entry);
|
|
BUG_ON(w->lock != lock);
|
|
|
|
return w;
|
|
}
|
|
|
|
static inline int task_has_pi_waiters(struct task_struct *p)
|
|
{
|
|
return !RB_EMPTY_ROOT(&p->pi_waiters);
|
|
}
|
|
|
|
static inline struct rt_mutex_waiter *
|
|
task_top_pi_waiter(struct task_struct *p)
|
|
{
|
|
return rb_entry(p->pi_waiters_leftmost, struct rt_mutex_waiter,
|
|
pi_tree_entry);
|
|
}
|
|
|
|
/*
|
|
* lock->owner state tracking:
|
|
*/
|
|
#define RT_MUTEX_HAS_WAITERS 1UL
|
|
#define RT_MUTEX_OWNER_MASKALL 1UL
|
|
|
|
static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
|
|
{
|
|
return (struct task_struct *)
|
|
((unsigned long)lock->owner & ~RT_MUTEX_OWNER_MASKALL);
|
|
}
|
|
|
|
/*
|
|
* PI-futex support (proxy locking functions, etc.):
|
|
*/
|
|
extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock);
|
|
extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
|
|
struct task_struct *proxy_owner);
|
|
extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
|
|
struct task_struct *proxy_owner);
|
|
extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
|
|
struct rt_mutex_waiter *waiter,
|
|
struct task_struct *task,
|
|
int detect_deadlock);
|
|
extern int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
|
|
struct hrtimer_sleeper *to,
|
|
struct rt_mutex_waiter *waiter,
|
|
int detect_deadlock);
|
|
|
|
#ifdef CONFIG_DEBUG_RT_MUTEXES
|
|
# include "rtmutex-debug.h"
|
|
#else
|
|
# include "rtmutex.h"
|
|
#endif
|
|
|
|
#endif
|