[linux-2.6-block.git] / include / linux / preempt_mask.h

#ifndef LINUX_PREEMPT_MASK_H
#define LINUX_PREEMPT_MASK_H

#include <linux/preempt.h>

/*
 * We put the hardirq and softirq counter into the preemption
 * counter. The bitmask has the following meaning:
 *
 * - bits 0-7 are the preemption count (max preemption depth: 256)
 * - bits 8-15 are the softirq count (max # of softirqs: 256)
 *
 * The hardirq count could in theory be the same as the number of
 * interrupts in the system, but we run all interrupt handlers with
 * interrupts disabled, so we cannot have nesting interrupts. Though
 * there are a few palaeontologic drivers which reenable interrupts in
 * the handler, so we need more than one bit here.
 *
 * PREEMPT_MASK:	0x000000ff
 * SOFTIRQ_MASK:	0x0000ff00
 * HARDIRQ_MASK:	0x000f0000
 *     NMI_MASK:	0x00100000
 * PREEMPT_ACTIVE:	0x00200000
 */
#define PREEMPT_BITS	8
#define SOFTIRQ_BITS	8
#define HARDIRQ_BITS	4
#define NMI_BITS	1

#define PREEMPT_SHIFT	0
#define SOFTIRQ_SHIFT	(PREEMPT_SHIFT + PREEMPT_BITS)
#define HARDIRQ_SHIFT	(SOFTIRQ_SHIFT + SOFTIRQ_BITS)
#define NMI_SHIFT	(HARDIRQ_SHIFT + HARDIRQ_BITS)

#define __IRQ_MASK(x)	((1UL << (x))-1)

#define PREEMPT_MASK	(__IRQ_MASK(PREEMPT_BITS) << PREEMPT_SHIFT)
#define SOFTIRQ_MASK	(__IRQ_MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT)
#define HARDIRQ_MASK	(__IRQ_MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT)
#define NMI_MASK	(__IRQ_MASK(NMI_BITS)     << NMI_SHIFT)

#define PREEMPT_OFFSET	(1UL << PREEMPT_SHIFT)
#define SOFTIRQ_OFFSET	(1UL << SOFTIRQ_SHIFT)
#define HARDIRQ_OFFSET	(1UL << HARDIRQ_SHIFT)
#define NMI_OFFSET	(1UL << NMI_SHIFT)

#define SOFTIRQ_DISABLE_OFFSET	(2 * SOFTIRQ_OFFSET)

#define PREEMPT_ACTIVE_BITS	1
#define PREEMPT_ACTIVE_SHIFT	(NMI_SHIFT + NMI_BITS)
#define PREEMPT_ACTIVE	(__IRQ_MASK(PREEMPT_ACTIVE_BITS) << PREEMPT_ACTIVE_SHIFT)

#define hardirq_count()	(preempt_count() & HARDIRQ_MASK)
#define softirq_count()	(preempt_count() & SOFTIRQ_MASK)
#define irq_count()	(preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK \
				 | NMI_MASK))

/*
 * Are we doing bottom half or hardware interrupt processing?
 * Are we in a softirq context? Interrupt context?
 * in_softirq - Are we currently processing softirq or have bh disabled?
 * in_serving_softirq - Are we currently processing softirq?
 */
#define in_irq()		(hardirq_count())
#define in_softirq()		(softirq_count())
#define in_interrupt()		(irq_count())
#define in_serving_softirq()	(softirq_count() & SOFTIRQ_OFFSET)

/*
 * Are we in NMI context?
 */
#define in_nmi()	(preempt_count() & NMI_MASK)

#if defined(CONFIG_PREEMPT_COUNT)
# define PREEMPT_CHECK_OFFSET 1
#else
# define PREEMPT_CHECK_OFFSET 0
#endif

/*
 * The preempt_count offset needed for things like:
 *
 *  spin_lock_bh()
 *
 * Which need to disable both preemption (CONFIG_PREEMPT_COUNT) and
 * softirqs, such that unlock sequences of:
 *
 *  spin_unlock();
 *  local_bh_enable();
 *
 * Work as expected.
 */
#define SOFTIRQ_LOCK_OFFSET (SOFTIRQ_DISABLE_OFFSET + PREEMPT_CHECK_OFFSET)

/*
 * Are we running in atomic context?  WARNING: this macro cannot
 * always detect atomic context; in particular, it cannot know about
 * held spinlocks in non-preemptible kernels.  Thus it should not be
 * used in the general case to determine whether sleeping is possible.
 * Do not use in_atomic() in driver code.
 */
#define in_atomic()	((preempt_count() & ~PREEMPT_ACTIVE) != 0)

/*
 * Check whether we were atomic before we did preempt_disable():
 * (used by the scheduler, *after* releasing the kernel lock)
 */
#define in_atomic_preempt_off() \
		((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_CHECK_OFFSET)

#ifdef CONFIG_PREEMPT_COUNT
# define preemptible()	(preempt_count() == 0 && !irqs_disabled())
#else
# define preemptible()	0
#endif

#endif /* LINUX_PREEMPT_MASK_H */
Commit	Line	Data
2d4b8473 FW	1	#ifndef LINUX_PREEMPT_MASK_H
	2	#define LINUX_PREEMPT_MASK_H
	3
	4	#include <linux/preempt.h>
2d4b8473 FW	5
	6	/*
	7	* We put the hardirq and softirq counter into the preemption
	8	* counter. The bitmask has the following meaning:
	9	*
	10	* - bits 0-7 are the preemption count (max preemption depth: 256)
	11	* - bits 8-15 are the softirq count (max # of softirqs: 256)
	12	*
54197e43 TG	13	* The hardirq count could in theory be the same as the number of
	14	* interrupts in the system, but we run all interrupt handlers with
	15	* interrupts disabled, so we cannot have nesting interrupts. Though
	16	* there are a few palaeontologic drivers which reenable interrupts in
	17	* the handler, so we need more than one bit here.
2d4b8473	18	*
00d1a39e TG	19	* PREEMPT_MASK: 0x000000ff
	20	* SOFTIRQ_MASK: 0x0000ff00
	21	* HARDIRQ_MASK: 0x000f0000
	22	* NMI_MASK: 0x00100000
	23	* PREEMPT_ACTIVE: 0x00200000
2d4b8473 FW	24	*/
	25	#define PREEMPT_BITS 8
	26	#define SOFTIRQ_BITS 8
54197e43	27	#define HARDIRQ_BITS 4
2d4b8473 FW	28	#define NMI_BITS 1
2d4b8473 FW	29
2d4b8473 FW	30	#define PREEMPT_SHIFT 0
	31	#define SOFTIRQ_SHIFT (PREEMPT_SHIFT + PREEMPT_BITS)
	32	#define HARDIRQ_SHIFT (SOFTIRQ_SHIFT + SOFTIRQ_BITS)
	33	#define NMI_SHIFT (HARDIRQ_SHIFT + HARDIRQ_BITS)
	34
	35	#define __IRQ_MASK(x) ((1UL << (x))-1)
	36
	37	#define PREEMPT_MASK (__IRQ_MASK(PREEMPT_BITS) << PREEMPT_SHIFT)
	38	#define SOFTIRQ_MASK (__IRQ_MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT)
	39	#define HARDIRQ_MASK (__IRQ_MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT)
	40	#define NMI_MASK (__IRQ_MASK(NMI_BITS) << NMI_SHIFT)
	41
	42	#define PREEMPT_OFFSET (1UL << PREEMPT_SHIFT)
	43	#define SOFTIRQ_OFFSET (1UL << SOFTIRQ_SHIFT)
	44	#define HARDIRQ_OFFSET (1UL << HARDIRQ_SHIFT)
	45	#define NMI_OFFSET (1UL << NMI_SHIFT)
	46
	47	#define SOFTIRQ_DISABLE_OFFSET (2 * SOFTIRQ_OFFSET)
	48
2d4b8473 FW	49	#define PREEMPT_ACTIVE_BITS 1
	50	#define PREEMPT_ACTIVE_SHIFT (NMI_SHIFT + NMI_BITS)
	51	#define PREEMPT_ACTIVE (__IRQ_MASK(PREEMPT_ACTIVE_BITS) << PREEMPT_ACTIVE_SHIFT)
2d4b8473 FW	52
	53	#define hardirq_count() (preempt_count() & HARDIRQ_MASK)
	54	#define softirq_count() (preempt_count() & SOFTIRQ_MASK)
	55	#define irq_count() (preempt_count() & (HARDIRQ_MASK \| SOFTIRQ_MASK \
	56	\| NMI_MASK))
	57
	58	/*
	59	* Are we doing bottom half or hardware interrupt processing?
	60	* Are we in a softirq context? Interrupt context?
	61	* in_softirq - Are we currently processing softirq or have bh disabled?
	62	* in_serving_softirq - Are we currently processing softirq?
	63	*/
	64	#define in_irq() (hardirq_count())
	65	#define in_softirq() (softirq_count())
	66	#define in_interrupt() (irq_count())
	67	#define in_serving_softirq() (softirq_count() & SOFTIRQ_OFFSET)
	68
	69	/*
	70	* Are we in NMI context?
	71	*/
	72	#define in_nmi() (preempt_count() & NMI_MASK)
	73
	74	#if defined(CONFIG_PREEMPT_COUNT)
	75	# define PREEMPT_CHECK_OFFSET 1
	76	#else
	77	# define PREEMPT_CHECK_OFFSET 0
	78	#endif
	79
9ea4c380 PZ	80	/*
	81	* The preempt_count offset needed for things like:
	82	*
	83	* spin_lock_bh()
	84	*
	85	* Which need to disable both preemption (CONFIG_PREEMPT_COUNT) and
	86	* softirqs, such that unlock sequences of:
	87	*
	88	* spin_unlock();
	89	* local_bh_enable();
	90	*
	91	* Work as expected.
	92	*/
	93	#define SOFTIRQ_LOCK_OFFSET (SOFTIRQ_DISABLE_OFFSET + PREEMPT_CHECK_OFFSET)
	94
2d4b8473 FW	95	/*
	96	* Are we running in atomic context? WARNING: this macro cannot
	97	* always detect atomic context; in particular, it cannot know about
	98	* held spinlocks in non-preemptible kernels. Thus it should not be
	99	* used in the general case to determine whether sleeping is possible.
	100	* Do not use in_atomic() in driver code.
	101	*/
	102	#define in_atomic() ((preempt_count() & ~PREEMPT_ACTIVE) != 0)
	103
	104	/*
	105	* Check whether we were atomic before we did preempt_disable():
	106	* (used by the scheduler, after releasing the kernel lock)
	107	*/
	108	#define in_atomic_preempt_off() \
	109	((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_CHECK_OFFSET)
	110
	111	#ifdef CONFIG_PREEMPT_COUNT
	112	# define preemptible() (preempt_count() == 0 && !irqs_disabled())
	113	#else
	114	# define preemptible() 0
	115	#endif
	116
	117	#endif /* LINUX_PREEMPT_MASK_H */