linux/include/linux/hardirq.h
<<
>>
Prefs
   1#ifndef LINUX_HARDIRQ_H
   2#define LINUX_HARDIRQ_H
   3
   4#include <linux/preempt.h>
   5#include <linux/lockdep.h>
   6#include <linux/ftrace_irq.h>
   7#include <asm/hardirq.h>
   8
   9/*
  10 * We put the hardirq and softirq counter into the preemption
  11 * counter. The bitmask has the following meaning:
  12 *
  13 * - bits 0-7 are the preemption count (max preemption depth: 256)
  14 * - bits 8-15 are the softirq count (max # of softirqs: 256)
  15 *
  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.
  22 *
  23 * - bits 16-25 are the hardirq count (max # of nested hardirqs: 1024)
  24 * - bit 26 is the NMI_MASK
  25 * - bit 27 is the PREEMPT_ACTIVE flag
  26 *
  27 * PREEMPT_MASK: 0x000000ff
  28 * SOFTIRQ_MASK: 0x0000ff00
  29 * HARDIRQ_MASK: 0x03ff0000
  30 *     NMI_MASK: 0x04000000
  31 */
  32#define PREEMPT_BITS    8
  33#define SOFTIRQ_BITS    8
  34#define NMI_BITS        1
  35
  36#define MAX_HARDIRQ_BITS 10
  37
  38#ifndef HARDIRQ_BITS
  39# define HARDIRQ_BITS   MAX_HARDIRQ_BITS
  40#endif
  41
  42#if HARDIRQ_BITS > MAX_HARDIRQ_BITS
  43#error HARDIRQ_BITS too high!
  44#endif
  45
  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)
  50
  51#define __IRQ_MASK(x)   ((1UL << (x))-1)
  52
  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)
  57
  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)
  62
  63#define SOFTIRQ_DISABLE_OFFSET  (2 * SOFTIRQ_OFFSET)
  64
  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
  70
  71#if PREEMPT_ACTIVE < (1 << (NMI_SHIFT + NMI_BITS))
  72#error PREEMPT_ACTIVE is too low!
  73#endif
  74
  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))
  79
  80/*
  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?
  85 */
  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)
  90
  91/*
  92 * Are we in NMI context?
  93 */
  94#define in_nmi()        (preempt_count() & NMI_MASK)
  95
  96#if defined(CONFIG_PREEMPT_COUNT)
  97# define PREEMPT_CHECK_OFFSET 1
  98#else
  99# define PREEMPT_CHECK_OFFSET 0
 100#endif
 101
 102/*
 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.
 108 */
 109#define in_atomic()     ((preempt_count() & ~PREEMPT_ACTIVE) != 0)
 110
 111/*
 112 * Check whether we were atomic before we did preempt_disable():
 113 * (used by the scheduler, *after* releasing the kernel lock)
 114 */
 115#define in_atomic_preempt_off() \
 116                ((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_CHECK_OFFSET)
 117
 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
 125
 126#if defined(CONFIG_SMP) || defined(CONFIG_GENERIC_HARDIRQS)
 127extern void synchronize_irq(unsigned int irq);
 128#else
 129# define synchronize_irq(irq)   barrier()
 130#endif
 131
 132struct task_struct;
 133
 134#if !defined(CONFIG_VIRT_CPU_ACCOUNTING) && !defined(CONFIG_IRQ_TIME_ACCOUNTING)
 135static inline void account_system_vtime(struct task_struct *tsk)
 136{
 137}
 138#else
 139extern void account_system_vtime(struct task_struct *tsk);
 140#endif
 141
 142#if defined(CONFIG_TINY_RCU) || defined(CONFIG_TINY_PREEMPT_RCU)
 143
 144static inline void rcu_nmi_enter(void)
 145{
 146}
 147
 148static inline void rcu_nmi_exit(void)
 149{
 150}
 151
 152#else
 153extern void rcu_nmi_enter(void);
 154extern void rcu_nmi_exit(void);
 155#endif
 156
 157/*
 158 * It is safe to do non-atomic ops on ->hardirq_context,
 159 * because NMI handlers may not preempt and the ops are
 160 * always balanced, so the interrupted value of ->hardirq_context
 161 * will always be restored.
 162 */
 163#define __irq_enter()                                   \
 164        do {                                            \
 165                account_system_vtime(current);          \
 166                add_preempt_count(HARDIRQ_OFFSET);      \
 167                trace_hardirq_enter();                  \
 168        } while (0)
 169
 170/*
 171 * Enter irq context (on NO_HZ, update jiffies):
 172 */
 173extern void irq_enter(void);
 174
 175/*
 176 * Exit irq context without processing softirqs:
 177 */
 178#define __irq_exit()                                    \
 179        do {                                            \
 180                trace_hardirq_exit();                   \
 181                account_system_vtime(current);          \
 182                sub_preempt_count(HARDIRQ_OFFSET);      \
 183        } while (0)
 184
 185/*
 186 * Exit irq context and process softirqs if needed:
 187 */
 188extern void irq_exit(void);
 189
 190#define nmi_enter()                                             \
 191        do {                                                    \
 192                ftrace_nmi_enter();                             \
 193                BUG_ON(in_nmi());                               \
 194                add_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET); \
 195                lockdep_off();                                  \
 196                rcu_nmi_enter();                                \
 197                trace_hardirq_enter();                          \
 198        } while (0)
 199
 200#define nmi_exit()                                              \
 201        do {                                                    \
 202                trace_hardirq_exit();                           \
 203                rcu_nmi_exit();                                 \
 204                lockdep_on();                                   \
 205                BUG_ON(!in_nmi());                              \
 206                sub_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET); \
 207                ftrace_nmi_exit();                              \
 208        } while (0)
 209
 210#endif /* LINUX_HARDIRQ_H */
 211
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.