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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>
128 lines
3.3 KiB
C
128 lines
3.3 KiB
C
/*
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* RT Mutexes: blocking mutual exclusion locks with PI support
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*
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* started by Ingo Molnar and Thomas Gleixner:
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*
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* Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
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* Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
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*
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* This file contains the private data structure and API definitions.
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*/
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#ifndef __KERNEL_RTMUTEX_COMMON_H
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#define __KERNEL_RTMUTEX_COMMON_H
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#include <linux/rtmutex.h>
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/*
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* The rtmutex in kernel tester is independent of rtmutex debugging. We
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* call schedule_rt_mutex_test() instead of schedule() for the tasks which
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* belong to the tester. That way we can delay the wakeup path of those
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* threads to provoke lock stealing and testing of complex boosting scenarios.
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*/
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#ifdef CONFIG_RT_MUTEX_TESTER
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extern void schedule_rt_mutex_test(struct rt_mutex *lock);
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#define schedule_rt_mutex(_lock) \
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do { \
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if (!(current->flags & PF_MUTEX_TESTER)) \
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schedule(); \
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else \
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schedule_rt_mutex_test(_lock); \
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} while (0)
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#else
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# define schedule_rt_mutex(_lock) schedule()
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#endif
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/*
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* This is the control structure for tasks blocked on a rt_mutex,
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* which is allocated on the kernel stack on of the blocked task.
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*
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* @tree_entry: pi node to enqueue into the mutex waiters tree
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* @pi_tree_entry: pi node to enqueue into the mutex owner waiters tree
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* @task: task reference to the blocked task
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*/
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struct rt_mutex_waiter {
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struct rb_node tree_entry;
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struct rb_node pi_tree_entry;
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struct task_struct *task;
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struct rt_mutex *lock;
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#ifdef CONFIG_DEBUG_RT_MUTEXES
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unsigned long ip;
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struct pid *deadlock_task_pid;
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struct rt_mutex *deadlock_lock;
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#endif
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int prio;
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};
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/*
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* Various helpers to access the waiters-tree:
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*/
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static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
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{
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return !RB_EMPTY_ROOT(&lock->waiters);
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}
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static inline struct rt_mutex_waiter *
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rt_mutex_top_waiter(struct rt_mutex *lock)
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{
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struct rt_mutex_waiter *w;
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w = rb_entry(lock->waiters_leftmost, struct rt_mutex_waiter,
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tree_entry);
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BUG_ON(w->lock != lock);
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return w;
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}
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static inline int task_has_pi_waiters(struct task_struct *p)
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{
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return !RB_EMPTY_ROOT(&p->pi_waiters);
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}
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static inline struct rt_mutex_waiter *
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task_top_pi_waiter(struct task_struct *p)
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{
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return rb_entry(p->pi_waiters_leftmost, struct rt_mutex_waiter,
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pi_tree_entry);
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}
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/*
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* lock->owner state tracking:
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*/
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#define RT_MUTEX_HAS_WAITERS 1UL
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#define RT_MUTEX_OWNER_MASKALL 1UL
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static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
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{
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return (struct task_struct *)
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((unsigned long)lock->owner & ~RT_MUTEX_OWNER_MASKALL);
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}
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/*
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* PI-futex support (proxy locking functions, etc.):
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*/
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extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock);
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extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
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struct task_struct *proxy_owner);
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extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
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struct task_struct *proxy_owner);
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extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
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struct rt_mutex_waiter *waiter,
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struct task_struct *task,
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int detect_deadlock);
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extern int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
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struct hrtimer_sleeper *to,
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struct rt_mutex_waiter *waiter,
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int detect_deadlock);
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#ifdef CONFIG_DEBUG_RT_MUTEXES
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# include "rtmutex-debug.h"
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#else
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# include "rtmutex.h"
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#endif
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#endif
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