MAINTAINERS: add CHAR and MISC driver maintainers
[zen-stable.git] / include / linux / hardirq.h
blobf743883f769e9bb38d82c901e19b5fdd7a1eada8
1 #ifndef LINUX_HARDIRQ_H
2 #define LINUX_HARDIRQ_H
4 #include <linux/preempt.h>
5 #include <linux/lockdep.h>
6 #include <linux/ftrace_irq.h>
7 #include <asm/hardirq.h>
9 /*
10 * We put the hardirq and softirq counter into the preemption
11 * counter. The bitmask has the following meaning:
13 * - bits 0-7 are the preemption count (max preemption depth: 256)
14 * - bits 8-15 are the softirq count (max # of softirqs: 256)
16 * The hardirq count can in theory reach the same as NR_IRQS.
17 * In reality, the number of nested IRQS is limited to the stack
18 * size as well. For archs with over 1000 IRQS it is not practical
19 * to expect that they will all nest. We give a max of 10 bits for
20 * hardirq nesting. An arch may choose to give less than 10 bits.
21 * m68k expects it to be 8.
23 * - bits 16-25 are the hardirq count (max # of nested hardirqs: 1024)
24 * - bit 26 is the NMI_MASK
25 * - bit 28 is the PREEMPT_ACTIVE flag
27 * PREEMPT_MASK: 0x000000ff
28 * SOFTIRQ_MASK: 0x0000ff00
29 * HARDIRQ_MASK: 0x03ff0000
30 * NMI_MASK: 0x04000000
32 #define PREEMPT_BITS 8
33 #define SOFTIRQ_BITS 8
34 #define NMI_BITS 1
36 #define MAX_HARDIRQ_BITS 10
38 #ifndef HARDIRQ_BITS
39 # define HARDIRQ_BITS MAX_HARDIRQ_BITS
40 #endif
42 #if HARDIRQ_BITS > MAX_HARDIRQ_BITS
43 #error HARDIRQ_BITS too high!
44 #endif
46 #define PREEMPT_SHIFT 0
47 #define SOFTIRQ_SHIFT (PREEMPT_SHIFT + PREEMPT_BITS)
48 #define HARDIRQ_SHIFT (SOFTIRQ_SHIFT + SOFTIRQ_BITS)
49 #define NMI_SHIFT (HARDIRQ_SHIFT + HARDIRQ_BITS)
51 #define __IRQ_MASK(x) ((1UL << (x))-1)
53 #define PREEMPT_MASK (__IRQ_MASK(PREEMPT_BITS) << PREEMPT_SHIFT)
54 #define SOFTIRQ_MASK (__IRQ_MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT)
55 #define HARDIRQ_MASK (__IRQ_MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT)
56 #define NMI_MASK (__IRQ_MASK(NMI_BITS) << NMI_SHIFT)
58 #define PREEMPT_OFFSET (1UL << PREEMPT_SHIFT)
59 #define SOFTIRQ_OFFSET (1UL << SOFTIRQ_SHIFT)
60 #define HARDIRQ_OFFSET (1UL << HARDIRQ_SHIFT)
61 #define NMI_OFFSET (1UL << NMI_SHIFT)
63 #define SOFTIRQ_DISABLE_OFFSET (2 * SOFTIRQ_OFFSET)
65 #ifndef PREEMPT_ACTIVE
66 #define PREEMPT_ACTIVE_BITS 1
67 #define PREEMPT_ACTIVE_SHIFT (NMI_SHIFT + NMI_BITS)
68 #define PREEMPT_ACTIVE (__IRQ_MASK(PREEMPT_ACTIVE_BITS) << PREEMPT_ACTIVE_SHIFT)
69 #endif
71 #if PREEMPT_ACTIVE < (1 << (NMI_SHIFT + NMI_BITS))
72 #error PREEMPT_ACTIVE is too low!
73 #endif
75 #define hardirq_count() (preempt_count() & HARDIRQ_MASK)
76 #define softirq_count() (preempt_count() & SOFTIRQ_MASK)
77 #define irq_count() (preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK \
78 | NMI_MASK))
81 * Are we doing bottom half or hardware interrupt processing?
82 * Are we in a softirq context? Interrupt context?
83 * in_softirq - Are we currently processing softirq or have bh disabled?
84 * in_serving_softirq - Are we currently processing softirq?
86 #define in_irq() (hardirq_count())
87 #define in_softirq() (softirq_count())
88 #define in_interrupt() (irq_count())
89 #define in_serving_softirq() (softirq_count() & SOFTIRQ_OFFSET)
92 * Are we in NMI context?
94 #define in_nmi() (preempt_count() & NMI_MASK)
96 #if defined(CONFIG_PREEMPT_COUNT)
97 # define PREEMPT_CHECK_OFFSET 1
98 #else
99 # define PREEMPT_CHECK_OFFSET 0
100 #endif
103 * Are we running in atomic context? WARNING: this macro cannot
104 * always detect atomic context; in particular, it cannot know about
105 * held spinlocks in non-preemptible kernels. Thus it should not be
106 * used in the general case to determine whether sleeping is possible.
107 * Do not use in_atomic() in driver code.
109 #define in_atomic() ((preempt_count() & ~PREEMPT_ACTIVE) != 0)
112 * Check whether we were atomic before we did preempt_disable():
113 * (used by the scheduler, *after* releasing the kernel lock)
115 #define in_atomic_preempt_off() \
116 ((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_CHECK_OFFSET)
118 #ifdef CONFIG_PREEMPT_COUNT
119 # define preemptible() (preempt_count() == 0 && !irqs_disabled())
120 # define IRQ_EXIT_OFFSET (HARDIRQ_OFFSET-1)
121 #else
122 # define preemptible() 0
123 # define IRQ_EXIT_OFFSET HARDIRQ_OFFSET
124 #endif
126 #if defined(CONFIG_SMP) || defined(CONFIG_GENERIC_HARDIRQS)
127 extern void synchronize_irq(unsigned int irq);
128 #else
129 # define synchronize_irq(irq) barrier()
130 #endif
132 struct task_struct;
134 #if !defined(CONFIG_VIRT_CPU_ACCOUNTING) && !defined(CONFIG_IRQ_TIME_ACCOUNTING)
135 static inline void account_system_vtime(struct task_struct *tsk)
138 #else
139 extern void account_system_vtime(struct task_struct *tsk);
140 #endif
142 #if defined(CONFIG_NO_HZ)
143 #if defined(CONFIG_TINY_RCU) || defined(CONFIG_TINY_PREEMPT_RCU)
144 extern void rcu_enter_nohz(void);
145 extern void rcu_exit_nohz(void);
147 static inline void rcu_irq_enter(void)
149 rcu_exit_nohz();
152 static inline void rcu_irq_exit(void)
154 rcu_enter_nohz();
157 static inline void rcu_nmi_enter(void)
161 static inline void rcu_nmi_exit(void)
165 #else
166 extern void rcu_irq_enter(void);
167 extern void rcu_irq_exit(void);
168 extern void rcu_nmi_enter(void);
169 extern void rcu_nmi_exit(void);
170 #endif
171 #else
172 # define rcu_irq_enter() do { } while (0)
173 # define rcu_irq_exit() do { } while (0)
174 # define rcu_nmi_enter() do { } while (0)
175 # define rcu_nmi_exit() do { } while (0)
176 #endif /* #if defined(CONFIG_NO_HZ) */
179 * It is safe to do non-atomic ops on ->hardirq_context,
180 * because NMI handlers may not preempt and the ops are
181 * always balanced, so the interrupted value of ->hardirq_context
182 * will always be restored.
184 #define __irq_enter() \
185 do { \
186 account_system_vtime(current); \
187 add_preempt_count(HARDIRQ_OFFSET); \
188 trace_hardirq_enter(); \
189 } while (0)
192 * Enter irq context (on NO_HZ, update jiffies):
194 extern void irq_enter(void);
197 * Exit irq context without processing softirqs:
199 #define __irq_exit() \
200 do { \
201 trace_hardirq_exit(); \
202 account_system_vtime(current); \
203 sub_preempt_count(HARDIRQ_OFFSET); \
204 } while (0)
207 * Exit irq context and process softirqs if needed:
209 extern void irq_exit(void);
211 #define nmi_enter() \
212 do { \
213 ftrace_nmi_enter(); \
214 BUG_ON(in_nmi()); \
215 add_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET); \
216 lockdep_off(); \
217 rcu_nmi_enter(); \
218 trace_hardirq_enter(); \
219 } while (0)
221 #define nmi_exit() \
222 do { \
223 trace_hardirq_exit(); \
224 rcu_nmi_exit(); \
225 lockdep_on(); \
226 BUG_ON(!in_nmi()); \
227 sub_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET); \
228 ftrace_nmi_exit(); \
229 } while (0)
231 #endif /* LINUX_HARDIRQ_H */