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![Davidlohr Bueso](/assets/img/avatar_default.png)
We have two flavors of the MCS spinlock: standard and cancelable (OSQ). While each one is independent of the other, we currently mix and match them. This patch: - Moves the OSQ code out of mcs_spinlock.h (which only deals with the traditional version) into include/linux/osq_lock.h. No unnecessary code is added to the more global header file, anything locks that make use of OSQ must include it anyway. - Renames mcs_spinlock.c to osq_lock.c. This file only contains osq code. - Introduces a CONFIG_LOCK_SPIN_ON_OWNER in order to only build osq_lock if there is support for it. Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Jason Low <jason.low2@hp.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mikulas Patocka <mpatocka@redhat.com> Cc: Waiman Long <Waiman.Long@hp.com> Link: http://lkml.kernel.org/r/1420573509-24774-5-git-send-email-dave@stgolabs.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
35 lines
899 B
C
35 lines
899 B
C
#ifndef __LINUX_OSQ_LOCK_H
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#define __LINUX_OSQ_LOCK_H
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/*
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* An MCS like lock especially tailored for optimistic spinning for sleeping
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* lock implementations (mutex, rwsem, etc).
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*/
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struct optimistic_spin_node {
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struct optimistic_spin_node *next, *prev;
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int locked; /* 1 if lock acquired */
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int cpu; /* encoded CPU # + 1 value */
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};
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struct optimistic_spin_queue {
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/*
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* Stores an encoded value of the CPU # of the tail node in the queue.
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* If the queue is empty, then it's set to OSQ_UNLOCKED_VAL.
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*/
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atomic_t tail;
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};
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#define OSQ_UNLOCKED_VAL (0)
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/* Init macro and function. */
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#define OSQ_LOCK_UNLOCKED { ATOMIC_INIT(OSQ_UNLOCKED_VAL) }
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static inline void osq_lock_init(struct optimistic_spin_queue *lock)
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{
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atomic_set(&lock->tail, OSQ_UNLOCKED_VAL);
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}
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extern bool osq_lock(struct optimistic_spin_queue *lock);
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extern void osq_unlock(struct optimistic_spin_queue *lock);
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#endif
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