hardirq.h revision 8e3e076c5a78519a9f64cd384e8f18bc21882ce0 
1#ifndef LINUX_HARDIRQ_H
2#define LINUX_HARDIRQ_H
3
4#include <linux/preempt.h>
5#include <linux/smp_lock.h>
6#include <linux/lockdep.h>
7#include <asm/hardirq.h>
8#include <asm/system.h>
9
10/*
11 * We put the hardirq and softirq counter into the preemption
12 * counter. The bitmask has the following meaning:
13 *
14 * - bits 0-7 are the preemption count (max preemption depth: 256)
15 * - bits 8-15 are the softirq count (max # of softirqs: 256)
16 *
17 * The hardirq count can be overridden per architecture, the default is:
18 *
19 * - bits 16-27 are the hardirq count (max # of hardirqs: 4096)
20 * - ( bit 28 is the PREEMPT_ACTIVE flag. )
21 *
22 * PREEMPT_MASK: 0x000000ff
23 * SOFTIRQ_MASK: 0x0000ff00
24 * HARDIRQ_MASK: 0x0fff0000
25 */
26#define PREEMPT_BITS	8
27#define SOFTIRQ_BITS	8
28
29#ifndef HARDIRQ_BITS
30#define HARDIRQ_BITS	12
31
32#ifndef MAX_HARDIRQS_PER_CPU
33#define MAX_HARDIRQS_PER_CPU NR_IRQS
34#endif
35
36/*
37 * The hardirq mask has to be large enough to have space for potentially
38 * all IRQ sources in the system nesting on a single CPU.
39 */
40#if (1 << HARDIRQ_BITS) < MAX_HARDIRQS_PER_CPU
41# error HARDIRQ_BITS is too low!
42#endif
43#endif
44
45#define PREEMPT_SHIFT	0
46#define SOFTIRQ_SHIFT	(PREEMPT_SHIFT + PREEMPT_BITS)
47#define HARDIRQ_SHIFT	(SOFTIRQ_SHIFT + SOFTIRQ_BITS)
48
49#define __IRQ_MASK(x)	((1UL << (x))-1)
50
51#define PREEMPT_MASK	(__IRQ_MASK(PREEMPT_BITS) << PREEMPT_SHIFT)
52#define SOFTIRQ_MASK	(__IRQ_MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT)
53#define HARDIRQ_MASK	(__IRQ_MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT)
54
55#define PREEMPT_OFFSET	(1UL << PREEMPT_SHIFT)
56#define SOFTIRQ_OFFSET	(1UL << SOFTIRQ_SHIFT)
57#define HARDIRQ_OFFSET	(1UL << HARDIRQ_SHIFT)
58
59#if PREEMPT_ACTIVE < (1 << (HARDIRQ_SHIFT + HARDIRQ_BITS))
60#error PREEMPT_ACTIVE is too low!
61#endif
62
63#define hardirq_count()	(preempt_count() & HARDIRQ_MASK)
64#define softirq_count()	(preempt_count() & SOFTIRQ_MASK)
65#define irq_count()	(preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK))
66
67/*
68 * Are we doing bottom half or hardware interrupt processing?
69 * Are we in a softirq context? Interrupt context?
70 */
71#define in_irq()		(hardirq_count())
72#define in_softirq()		(softirq_count())
73#define in_interrupt()		(irq_count())
74
75#if defined(CONFIG_PREEMPT)
76# define PREEMPT_INATOMIC_BASE kernel_locked()
77# define PREEMPT_CHECK_OFFSET 1
78#else
79# define PREEMPT_INATOMIC_BASE 0
80# define PREEMPT_CHECK_OFFSET 0
81#endif
82
83/*
84 * Are we running in atomic context?  WARNING: this macro cannot
85 * always detect atomic context; in particular, it cannot know about
86 * held spinlocks in non-preemptible kernels.  Thus it should not be
87 * used in the general case to determine whether sleeping is possible.
88 * Do not use in_atomic() in driver code.
89 */
90#define in_atomic()	((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_INATOMIC_BASE)
91
92/*
93 * Check whether we were atomic before we did preempt_disable():
94 * (used by the scheduler, *after* releasing the kernel lock)
95 */
96#define in_atomic_preempt_off() \
97		((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_CHECK_OFFSET)
98
99#ifdef CONFIG_PREEMPT
100# define preemptible()	(preempt_count() == 0 && !irqs_disabled())
101# define IRQ_EXIT_OFFSET (HARDIRQ_OFFSET-1)
102#else
103# define preemptible()	0
104# define IRQ_EXIT_OFFSET HARDIRQ_OFFSET
105#endif
106
107#ifdef CONFIG_SMP
108extern void synchronize_irq(unsigned int irq);
109#else
110# define synchronize_irq(irq)	barrier()
111#endif
112
113struct task_struct;
114
115#ifndef CONFIG_VIRT_CPU_ACCOUNTING
116static inline void account_system_vtime(struct task_struct *tsk)
117{
118}
119#endif
120
121#if defined(CONFIG_PREEMPT_RCU) && defined(CONFIG_NO_HZ)
122extern void rcu_irq_enter(void);
123extern void rcu_irq_exit(void);
124#else
125# define rcu_irq_enter() do { } while (0)
126# define rcu_irq_exit() do { } while (0)
127#endif /* CONFIG_PREEMPT_RCU */
128
129/*
130 * It is safe to do non-atomic ops on ->hardirq_context,
131 * because NMI handlers may not preempt and the ops are
132 * always balanced, so the interrupted value of ->hardirq_context
133 * will always be restored.
134 */
135#define __irq_enter()					\
136	do {						\
137		rcu_irq_enter();			\
138		account_system_vtime(current);		\
139		add_preempt_count(HARDIRQ_OFFSET);	\
140		trace_hardirq_enter();			\
141	} while (0)
142
143/*
144 * Enter irq context (on NO_HZ, update jiffies):
145 */
146extern void irq_enter(void);
147
148/*
149 * Exit irq context without processing softirqs:
150 */
151#define __irq_exit()					\
152	do {						\
153		trace_hardirq_exit();			\
154		account_system_vtime(current);		\
155		sub_preempt_count(HARDIRQ_OFFSET);	\
156		rcu_irq_exit();				\
157	} while (0)
158
159/*
160 * Exit irq context and process softirqs if needed:
161 */
162extern void irq_exit(void);
163
164#define nmi_enter()		do { lockdep_off(); __irq_enter(); } while (0)
165#define nmi_exit()		do { __irq_exit(); lockdep_on(); } while (0)
166
167#endif /* LINUX_HARDIRQ_H */
168