cregit-Linux how code gets into the kernel

Release 4.12 include/asm-generic/qspinlock_types.h

/*
 * Queued spinlock
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * (C) Copyright 2013-2015 Hewlett-Packard Development Company, L.P.
 *
 * Authors: Waiman Long <waiman.long@hp.com>
 */
#ifndef __ASM_GENERIC_QSPINLOCK_TYPES_H

#define __ASM_GENERIC_QSPINLOCK_TYPES_H

/*
 * Including atomic.h with PARAVIRT on will cause compilation errors because
 * of recursive header file incluson via paravirt_types.h. So don't include
 * it if PARAVIRT is on.
 */
#ifndef CONFIG_PARAVIRT
#include <linux/types.h>
#include <linux/atomic.h>
#endif


typedef struct qspinlock {
	
atomic_t	val;

} arch_spinlock_t;

/*
 * Initializier
 */

#define	__ARCH_SPIN_LOCK_UNLOCKED	{ ATOMIC_INIT(0) }

/*
 * Bitfields in the atomic value:
 *
 * When NR_CPUS < 16K
 *  0- 7: locked byte
 *     8: pending
 *  9-15: not used
 * 16-17: tail index
 * 18-31: tail cpu (+1)
 *
 * When NR_CPUS >= 16K
 *  0- 7: locked byte
 *     8: pending
 *  9-10: tail index
 * 11-31: tail cpu (+1)
 */

#define	_Q_SET_MASK(type)	(((1U << _Q_ ## type ## _BITS) - 1)\
                                      << _Q_ ## type ## _OFFSET)

#define _Q_LOCKED_OFFSET	0

#define _Q_LOCKED_BITS		8

#define _Q_LOCKED_MASK		_Q_SET_MASK(LOCKED)


#define _Q_PENDING_OFFSET	(_Q_LOCKED_OFFSET + _Q_LOCKED_BITS)
#if CONFIG_NR_CPUS < (1U << 14)

#define _Q_PENDING_BITS		8
#else

#define _Q_PENDING_BITS		1
#endif

#define _Q_PENDING_MASK		_Q_SET_MASK(PENDING)


#define _Q_TAIL_IDX_OFFSET	(_Q_PENDING_OFFSET + _Q_PENDING_BITS)

#define _Q_TAIL_IDX_BITS	2

#define _Q_TAIL_IDX_MASK	_Q_SET_MASK(TAIL_IDX)


#define _Q_TAIL_CPU_OFFSET	(_Q_TAIL_IDX_OFFSET + _Q_TAIL_IDX_BITS)

#define _Q_TAIL_CPU_BITS	(32 - _Q_TAIL_CPU_OFFSET)

#define _Q_TAIL_CPU_MASK	_Q_SET_MASK(TAIL_CPU)


#define _Q_TAIL_OFFSET		_Q_TAIL_IDX_OFFSET

#define _Q_TAIL_MASK		(_Q_TAIL_IDX_MASK | _Q_TAIL_CPU_MASK)


#define _Q_LOCKED_VAL		(1U << _Q_LOCKED_OFFSET)

#define _Q_PENDING_VAL		(1U << _Q_PENDING_OFFSET)

#endif /* __ASM_GENERIC_QSPINLOCK_TYPES_H */

Overall Contributors

PersonTokensPropCommitsCommitProp
Waiman Long8265.08%240.00%
Peter Zijlstra3930.95%240.00%
Dan Streetman53.97%120.00%
Total126100.00%5100.00%
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