fb00aca474
Turn the pi-chains from plist to rb-tree, in the rt_mutex code, and provide a proper comparison function for -deadline and -priority tasks. This is done mainly because: - classical prio field of the plist is just an int, which might not be enough for representing a deadline; - manipulating such a list would become O(nr_deadline_tasks), which might be to much, as the number of -deadline task increases. Therefore, an rb-tree is used, and tasks are queued in it according to the following logic: - among two -priority (i.e., SCHED_BATCH/OTHER/RR/FIFO) tasks, the one with the higher (lower, actually!) prio wins; - among a -priority and a -deadline task, the latter always wins; - among two -deadline tasks, the one with the earliest deadline wins. Queueing and dequeueing functions are changed accordingly, for both the list of a task's pi-waiters and the list of tasks blocked on a pi-lock. Signed-off-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Dario Faggioli <raistlin@linux.it> Signed-off-by: Juri Lelli <juri.lelli@gmail.com> Signed-off-again-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1383831828-15501-10-git-send-email-juri.lelli@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
103 lines
2.9 KiB
C
103 lines
2.9 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 public data structure and API definitions.
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*/
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#ifndef __LINUX_RT_MUTEX_H
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#define __LINUX_RT_MUTEX_H
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#include <linux/linkage.h>
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#include <linux/rbtree.h>
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#include <linux/spinlock_types.h>
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extern int max_lock_depth; /* for sysctl */
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/**
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* The rt_mutex structure
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*
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* @wait_lock: spinlock to protect the structure
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* @waiters: rbtree root to enqueue waiters in priority order
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* @waiters_leftmost: top waiter
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* @owner: the mutex owner
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*/
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struct rt_mutex {
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raw_spinlock_t wait_lock;
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struct rb_root waiters;
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struct rb_node *waiters_leftmost;
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struct task_struct *owner;
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#ifdef CONFIG_DEBUG_RT_MUTEXES
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int save_state;
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const char *name, *file;
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int line;
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void *magic;
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#endif
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};
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struct rt_mutex_waiter;
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struct hrtimer_sleeper;
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#ifdef CONFIG_DEBUG_RT_MUTEXES
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extern int rt_mutex_debug_check_no_locks_freed(const void *from,
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unsigned long len);
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extern void rt_mutex_debug_check_no_locks_held(struct task_struct *task);
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#else
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static inline int rt_mutex_debug_check_no_locks_freed(const void *from,
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unsigned long len)
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{
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return 0;
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}
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# define rt_mutex_debug_check_no_locks_held(task) do { } while (0)
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#endif
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#ifdef CONFIG_DEBUG_RT_MUTEXES
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# define __DEBUG_RT_MUTEX_INITIALIZER(mutexname) \
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, .name = #mutexname, .file = __FILE__, .line = __LINE__
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# define rt_mutex_init(mutex) __rt_mutex_init(mutex, __func__)
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extern void rt_mutex_debug_task_free(struct task_struct *tsk);
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#else
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# define __DEBUG_RT_MUTEX_INITIALIZER(mutexname)
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# define rt_mutex_init(mutex) __rt_mutex_init(mutex, NULL)
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# define rt_mutex_debug_task_free(t) do { } while (0)
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#endif
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#define __RT_MUTEX_INITIALIZER(mutexname) \
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{ .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(mutexname.wait_lock) \
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, .waiters = RB_ROOT \
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, .owner = NULL \
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__DEBUG_RT_MUTEX_INITIALIZER(mutexname)}
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#define DEFINE_RT_MUTEX(mutexname) \
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struct rt_mutex mutexname = __RT_MUTEX_INITIALIZER(mutexname)
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/**
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* rt_mutex_is_locked - is the mutex locked
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* @lock: the mutex to be queried
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*
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* Returns 1 if the mutex is locked, 0 if unlocked.
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*/
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static inline int rt_mutex_is_locked(struct rt_mutex *lock)
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{
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return lock->owner != NULL;
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}
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extern void __rt_mutex_init(struct rt_mutex *lock, const char *name);
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extern void rt_mutex_destroy(struct rt_mutex *lock);
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extern void rt_mutex_lock(struct rt_mutex *lock);
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extern int rt_mutex_lock_interruptible(struct rt_mutex *lock,
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int detect_deadlock);
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extern int rt_mutex_timed_lock(struct rt_mutex *lock,
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struct hrtimer_sleeper *timeout,
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int detect_deadlock);
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extern int rt_mutex_trylock(struct rt_mutex *lock);
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extern void rt_mutex_unlock(struct rt_mutex *lock);
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#endif
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