include/linux/preempt_mask.h

   1 #ifndef LINUX_PREEMPT_MASK_H
   2 #define LINUX_PREEMPT_MASK_H
   3
   4 #include <linux/preempt.h>
   5
   6 /*
   7  * We put the hardirq and softirq counter into the preemption
   8  * counter. The bitmask has the following meaning:
   9  *
  10  * - bits 0-7 are the preemption count (max preemption depth: 256)
  11  * - bits 8-15 are the softirq count (max # of softirqs: 256)
  12  *
  13  * The hardirq count could in theory be the same as the number of
  14  * interrupts in the system, but we run all interrupt handlers with
  15  * interrupts disabled, so we cannot have nesting interrupts. Though
  16  * there are a few palaeontologic drivers which reenable interrupts in
  17  * the handler, so we need more than one bit here.
  18  *
  19  * PREEMPT_MASK:        0x000000ff
  20  * SOFTIRQ_MASK:        0x0000ff00
  21  * HARDIRQ_MASK:        0x000f0000
  22  *     NMI_MASK:        0x00100000
  23  * PREEMPT_ACTIVE:      0x00200000
  24  */
  25 #define PREEMPT_BITS    8
  26 #define SOFTIRQ_BITS    8
  27 #define HARDIRQ_BITS    4
  28 #define NMI_BITS        1
  29
  30 #define PREEMPT_SHIFT   0
  31 #define SOFTIRQ_SHIFT   (PREEMPT_SHIFT + PREEMPT_BITS)
  32 #define HARDIRQ_SHIFT   (SOFTIRQ_SHIFT + SOFTIRQ_BITS)
  33 #define NMI_SHIFT       (HARDIRQ_SHIFT + HARDIRQ_BITS)
  34
  35 #define __IRQ_MASK(x)   ((1UL << (x))-1)
  36
  37 #define PREEMPT_MASK    (__IRQ_MASK(PREEMPT_BITS) << PREEMPT_SHIFT)
  38 #define SOFTIRQ_MASK    (__IRQ_MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT)
  39 #define HARDIRQ_MASK    (__IRQ_MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT)
  40 #define NMI_MASK        (__IRQ_MASK(NMI_BITS)     << NMI_SHIFT)
  41
  42 #define PREEMPT_OFFSET  (1UL << PREEMPT_SHIFT)
  43 #define SOFTIRQ_OFFSET  (1UL << SOFTIRQ_SHIFT)
  44 #define HARDIRQ_OFFSET  (1UL << HARDIRQ_SHIFT)
  45 #define NMI_OFFSET      (1UL << NMI_SHIFT)
  46
  47 #define SOFTIRQ_DISABLE_OFFSET  (2 * SOFTIRQ_OFFSET)
  48
  49 #define PREEMPT_ACTIVE_BITS     1
  50 #define PREEMPT_ACTIVE_SHIFT    (NMI_SHIFT + NMI_BITS)
  51 #define PREEMPT_ACTIVE  (__IRQ_MASK(PREEMPT_ACTIVE_BITS) << PREEMPT_ACTIVE_SHIFT)
  52
  53 #define hardirq_count() (preempt_count() & HARDIRQ_MASK)
  54 #define softirq_count() (preempt_count() & SOFTIRQ_MASK)
  55 #define irq_count()     (preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK \
  56                                  | NMI_MASK))
  57
  58 /*
  59  * Are we doing bottom half or hardware interrupt processing?
  60  * Are we in a softirq context? Interrupt context?
  61  * in_softirq - Are we currently processing softirq or have bh disabled?
  62  * in_serving_softirq - Are we currently processing softirq?
  63  */
  64 #define in_irq()                (hardirq_count())
  65 #define in_softirq()            (softirq_count())
  66 #define in_interrupt()          (irq_count())
  67 #define in_serving_softirq()    (softirq_count() & SOFTIRQ_OFFSET)
  68
  69 /*
  70  * Are we in NMI context?
  71  */
  72 #define in_nmi()        (preempt_count() & NMI_MASK)
  73
  74 #if defined(CONFIG_PREEMPT_COUNT)
  75 # define PREEMPT_CHECK_OFFSET 1
  76 #else
  77 # define PREEMPT_CHECK_OFFSET 0
  78 #endif
  79
  80 /*
  81  * The preempt_count offset needed for things like:
  82  *
  83  *  spin_lock_bh()
  84  *
  85  * Which need to disable both preemption (CONFIG_PREEMPT_COUNT) and
  86  * softirqs, such that unlock sequences of:
  87  *
  88  *  spin_unlock();
  89  *  local_bh_enable();
  90  *
  91  * Work as expected.
  92  */
  93 #define SOFTIRQ_LOCK_OFFSET (SOFTIRQ_DISABLE_OFFSET + PREEMPT_CHECK_OFFSET)
  94
  95 /*
  96  * Are we running in atomic context?  WARNING: this macro cannot
  97  * always detect atomic context; in particular, it cannot know about
  98  * held spinlocks in non-preemptible kernels.  Thus it should not be
  99  * used in the general case to determine whether sleeping is possible.
 100  * Do not use in_atomic() in driver code.
 101  */
 102 #define in_atomic()     ((preempt_count() & ~PREEMPT_ACTIVE) != 0)
 103
 104 /*
 105  * Check whether we were atomic before we did preempt_disable():
 106  * (used by the scheduler, *after* releasing the kernel lock)
 107  */
 108 #define in_atomic_preempt_off() \
 109                 ((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_CHECK_OFFSET)
 110
 111 #ifdef CONFIG_PREEMPT_COUNT
 112 # define preemptible()  (preempt_count() == 0 && !irqs_disabled())
 113 #else
 114 # define preemptible()  0
 115 #endif
 116
 117 #endif /* LINUX_PREEMPT_MASK_H */