LXR linux/include/linux/hardirq.h

   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