d84b6728c5
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>
36 lines
899 B
C
36 lines
899 B
C
#ifndef __LINUX_OSQ_LOCK_H
|
|
#define __LINUX_OSQ_LOCK_H
|
|
|
|
/*
|
|
* An MCS like lock especially tailored for optimistic spinning for sleeping
|
|
* lock implementations (mutex, rwsem, etc).
|
|
*/
|
|
struct optimistic_spin_node {
|
|
struct optimistic_spin_node *next, *prev;
|
|
int locked; /* 1 if lock acquired */
|
|
int cpu; /* encoded CPU # + 1 value */
|
|
};
|
|
|
|
struct optimistic_spin_queue {
|
|
/*
|
|
* Stores an encoded value of the CPU # of the tail node in the queue.
|
|
* If the queue is empty, then it's set to OSQ_UNLOCKED_VAL.
|
|
*/
|
|
atomic_t tail;
|
|
};
|
|
|
|
#define OSQ_UNLOCKED_VAL (0)
|
|
|
|
/* Init macro and function. */
|
|
#define OSQ_LOCK_UNLOCKED { ATOMIC_INIT(OSQ_UNLOCKED_VAL) }
|
|
|
|
static inline void osq_lock_init(struct optimistic_spin_queue *lock)
|
|
{
|
|
atomic_set(&lock->tail, OSQ_UNLOCKED_VAL);
|
|
}
|
|
|
|
extern bool osq_lock(struct optimistic_spin_queue *lock);
|
|
extern void osq_unlock(struct optimistic_spin_queue *lock);
|
|
|
|
#endif
|