litmus-rt.git - The LITMUS^RT kernel.

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author	Mohammad Merajul Islam Molla <meraj.enigma@gmail.com>	2014-07-27 23:58:50 -0400
committer	Rafael J. Wysocki <rafael.j.wysocki@intel.com>	2014-07-28 19:31:13 -0400
commit	1469244613dadeccc563982b3246500913e26d61 (patch)
tree	f26744c8e59b1c663bab34e1a10ce8544f5e73f1 /scripts/objdiff
parent	6ee7f5dd57fc2e0450d0a41ec1320c06425335e0 (diff)

cpuidle: ladder governor - use macro instead of hardcoded value

use CPUIDLE_DRIVER_STATE_START, instead of hardcoded value 0. As, CPUIDLE_DRIVER_STATE_START can be 1/0 based on CONFIG_ARCH_HAS_CPU_RELAX is defined or not. Signed-off-by: Mohammad Merajul Islam Molla <meraj.enigma@gmail.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Diffstat (limited to 'scripts/objdiff')

0 files changed, 0 insertions, 0 deletions

/* rwsem-spinlock.c: R/W semaphores: contention handling functions for * generic spinlock implementation * * Copyright (c) 2001 David Howells (dhowells@redhat.com). * - Derived partially from idea by Andrea Arcangeli <andrea@suse.de> * - Derived also from comments by Linus */ #include <linux/rwsem.h> #include <linux/sched.h> #include <linux/module.h> struct rwsem_waiter { struct list_head list; struct task_struct *task; unsigned int flags; #define RWSEM_WAITING_FOR_READ 0x00000001 #define RWSEM_WAITING_FOR_WRITE 0x00000002 }; /* * initialise the semaphore */ void __init_rwsem(struct rw_semaphore *sem, const char *name, struct lock_class_key *key) { #ifdef CONFIG_DEBUG_LOCK_ALLOC /* * Make sure we are not reinitializing a held semaphore: */ debug_check_no_locks_freed((void *)sem, sizeof(*sem)); lockdep_init_map(&sem->dep_map, name, key, 0); #endif sem->activity = 0; spin_lock_init(&sem->wait_lock); INIT_LIST_HEAD(&sem->wait_list); } /* * handle the lock release when processes blocked on it that can now run * - if we come here, then: * - the 'active count' _reached_ zero * - the 'waiting count' is non-zero * - the spinlock must be held by the caller * - woken process blocks are discarded from the list after having task zeroed * - writers are only woken if wakewrite is non-zero */ static inline struct rw_semaphore * __rwsem_do_wake(struct rw_semaphore *sem, int wakewrite) { struct rwsem_waiter *waiter; struct task_struct *tsk; int woken; waiter = list_entry(sem->wait_list.next, struct rwsem_waiter, list); if (!wakewrite) { if (waiter->flags & RWSEM_WAITING_FOR_WRITE) goto out; goto dont_wake_writers; } /* if we are allowed to wake writers try to grant a single write lock * if there's a writer at the front of the queue * - we leave the 'waiting count' incremented to signify potential * contention */ if (waiter->flags & RWSEM_WAITING_FOR_WRITE) { sem->activity = -1; list_del(&waiter->list); tsk = waiter->task; /* Don't touch waiter after ->task has been NULLed */ smp_mb(); waiter->task = NULL; wake_up_process(tsk); put_task_struct(tsk); goto out; } /* grant an infinite number of read locks to the front of the queue */ dont_wake_writers: woken = 0; while (waiter->flags & RWSEM_WAITING_FOR_READ) { struct list_head *next = waiter->list.next; list_del(&waiter->list); tsk = waiter->task; smp_mb(); waiter->task = NULL; wake_up_process(tsk); put_task_struct(tsk); woken++; if (list_empty(&sem->wait_list)) break; waiter = list_entry(next, struct rwsem_waiter, list); } sem->activity += woken; out: return sem; } /* * wake a single writer */ static inline struct rw_semaphore * __rwsem_wake_one_writer(struct rw_semaphore *sem) { struct rwsem_waiter *waiter; struct task_struct *tsk; sem->activity = -1; waiter = list_entry(sem->wait_list.next, struct rwsem_waiter, list); list_del(&waiter->list); tsk = waiter->task; smp_mb(); waiter->task = NULL; wake_up_process(tsk); put_task_struct(tsk); return sem; } /* * get a read lock on the semaphore */ void __sched __down_read(struct rw_semaphore *sem) { struct rwsem_waiter waiter; struct task_struct *tsk; spin_lock_irq(&sem->wait_lock); if (sem->activity >= 0 && list_empty(&sem->wait_list)) { /* granted */ sem->activity++; spin_unlock_irq(&sem->wait_lock); goto out; } tsk = current; set_task_state(tsk, TASK_UNINTERRUPTIBLE); /* set up my own style of waitqueue */ waiter.task = tsk; waiter.flags = RWSEM_WAITING_FOR_READ; get_task_struct(tsk); list_add_tail(&waiter.list, &sem->wait_list); /* we don't need to touch the semaphore struct anymore */ spin_unlock_irq(&sem->wait_lock); /* wait to be given the lock */ for (;;) { if (!waiter.task) break; schedule(); set_task_state(tsk, TASK_UNINTERRUPTIBLE); } tsk->state = TASK_RUNNING; out: ; } /* * trylock for reading -- returns 1 if successful, 0 if contention */ int __down_read_trylock(struct rw_semaphore *sem) { unsigned long flags; int ret = 0; spin_lock_irqsave(&sem->wait_lock, flags); if (sem->activity >= 0 && list_empty(&sem->wait_list)) { /* granted */ sem->activity++; ret = 1; } spin_unlock_irqrestore(&sem->wait_lock, flags); return ret; } /* * get a write lock on the semaphore * - we increment the waiting count anyway to indicate an exclusive lock */ void __sched __down_write_nested(struct rw_semaphore *sem, int subclass) { struct rwsem_waiter waiter; struct task_struct *tsk; spin_lock_irq(&sem->wait_lock); if (sem->activity == 0 && list_empty(&sem->wait_list)) { /* granted */ sem->activity = -1; spin_unlock_irq(&sem->wait_lock); goto out; } tsk = current; set_task_state(tsk, TASK_UNINTERRUPTIBLE); /* set up my own style of waitqueue */ waiter.task = tsk; waiter.flags = RWSEM_WAITING_FOR_WRITE; get_task_struct(tsk); list_add_tail(&waiter.list, &sem->wait_list); /* we don't need to touch the semaphore struct anymore */ spin_unlock_irq(&sem->wait_lock); /* wait to be given the lock */ for (;;) { if (!waiter.task) break; schedule(); set_task_state(tsk, TASK_UNINTERRUPTIBLE); } tsk->state = TASK_RUNNING; out: ; } void __sched __down_write(struct rw_semaphore *sem) { __down_write_nested(sem, 0); } /* * trylock for writing -- returns 1 if successful, 0 if contention */ int __down_write_trylock(struct rw_semaphore *sem) { unsigned long flags; int ret = 0; spin_lock_irqsave(&sem->wait_lock, flags); if (sem->activity == 0 && list_empty(&sem->wait_list)) { /* granted */ sem->activity = -1; ret = 1; } spin_unlock_irqrestore(&sem->wait_lock, flags); return ret; } /* * release a read lock on the semaphore */ void __up_read(struct rw_semaphore *sem) { unsigned long flags; spin_lock_irqsave(&sem->wait_lock, flags); if (--sem->activity == 0 && !list_empty(&sem->wait_list)) sem = __rwsem_wake_one_writer(sem); spin_unlock_irqrestore(&sem->wait_lock, flags); } /* * release a write lock on the semaphore */ void __up_write(struct rw_semaphore *sem) { unsigned long flags; spin_lock_irqsave(&sem->wait_lock, flags); sem->activity = 0; if (!list_empty(&sem->wait_list)) sem = __rwsem_do_wake(sem, 1); spin_unlock_irqrestore(&sem->wait_lock, flags); } /* * downgrade a write lock into a read lock * - just wake up any readers at the front of the queue */ void __downgrade_write(struct rw_semaphore *sem) { unsigned long flags; spin_lock_irqsave(&sem->wait_lock, flags); sem->activity = 1; if (!list_empty(&sem->wait_list)) sem = __rwsem_do_wake(sem, 0); spin_unlock_irqrestore(&sem->wait_lock, flags); } EXPORT_SYMBOL(__init_rwsem); EXPORT_SYMBOL(__down_read); EXPORT_SYMBOL(__down_read_trylock); EXPORT_SYMBOL(__down_write_nested); EXPORT_SYMBOL(__down_write); EXPORT_SYMBOL(__down_write_trylock); EXPORT_SYMBOL(__up_read); EXPORT_SYMBOL(__up_write); EXPORT_SYMBOL(__downgrade_write);


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