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) && !defined(CONFIG_PREEMPT_BKL)
  76 # define in_atomic()    ((preempt_count() & ~PREEMPT_ACTIVE) != kernel_locked())
  77 #else
  78 # define in_atomic()    ((preempt_count() & ~PREEMPT_ACTIVE) != 0)
  79 #endif
  80
  81 #ifdef CONFIG_PREEMPT
  82 # define PREEMPT_CHECK_OFFSET 1
  83 #else
  84 # define PREEMPT_CHECK_OFFSET 0
  85 #endif
  86
  87 /*
  88  * Check whether we were atomic before we did preempt_disable():
  89  * (used by the scheduler)
  90  */
  91 #define in_atomic_preempt_off() \
  92                 ((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_CHECK_OFFSET)
  93
  94 #ifdef CONFIG_PREEMPT
  95 # define preemptible()  (preempt_count() == 0 && !irqs_disabled())
  96 # define IRQ_EXIT_OFFSET (HARDIRQ_OFFSET-1)
  97 #else
  98 # define preemptible()  0
  99 # define IRQ_EXIT_OFFSET HARDIRQ_OFFSET
 100 #endif
 101
 102 #ifdef CONFIG_SMP
 103 extern void synchronize_irq(unsigned int irq);
 104 #else
 105 # define synchronize_irq(irq)   barrier()
 106 #endif
 107
 108 struct task_struct;
 109
 110 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
 111 static inline void account_system_vtime(struct task_struct *tsk)
 112 {
 113 }
 114 #endif
 115
 116 /*
 117  * It is safe to do non-atomic ops on ->hardirq_context,
 118  * because NMI handlers may not preempt and the ops are
 119  * always balanced, so the interrupted value of ->hardirq_context
 120  * will always be restored.
 121  */
 122 #define __irq_enter()                                   \
 123         do {                                            \
 124                 account_system_vtime(current);          \
 125                 add_preempt_count(HARDIRQ_OFFSET);      \
 126                 trace_hardirq_enter();                  \
 127         } while (0)
 128
 129 /*
 130  * Enter irq context (on NO_HZ, update jiffies):
 131  */
 132 extern void irq_enter(void);
 133
 134 /*
 135  * Exit irq context without processing softirqs:
 136  */
 137 #define __irq_exit()                                    \
 138         do {                                            \
 139                 trace_hardirq_exit();                   \
 140                 account_system_vtime(current);          \
 141                 sub_preempt_count(HARDIRQ_OFFSET);      \
 142         } while (0)
 143
 144 /*
 145  * Exit irq context and process softirqs if needed:
 146  */
 147 extern void irq_exit(void);
 148
 149 #define nmi_enter()             do { lockdep_off(); __irq_enter(); } while (0)
 150 #define nmi_exit()              do { __irq_exit(); lockdep_on(); } while (0)
 151
 152 #endif /* LINUX_HARDIRQ_H */