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
 108 extern void synchronize_irq(unsigned int irq);
 109 #else
 110 # define synchronize_irq(irq)   barrier()
 111 #endif
 112
 113 struct task_struct;
 114
 115 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
 116 static inline void account_system_vtime(struct task_struct *tsk)
 117 {
 118 }
 119 #endif
 120
 121 #if defined(CONFIG_PREEMPT_RCU) && defined(CONFIG_NO_HZ)
 122 extern void rcu_irq_enter(void);
 123 extern 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  */
 146 extern 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  */
 162 extern 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 */