include/linux/preempt_mask.h

   1 #ifndef LINUX_PREEMPT_MASK_H
   2 #define LINUX_PREEMPT_MASK_H
   3
   4 #include <linux/preempt.h>
   5 #include <asm/hardirq.h>
   6
   7 /*
   8  * We put the hardirq and softirq counter into the preemption
   9  * counter. The bitmask has the following meaning:
  10  *
  11  * - bits 0-7 are the preemption count (max preemption depth: 256)
  12  * - bits 8-15 are the softirq count (max # of softirqs: 256)
  13  *
  14  * The hardirq count can in theory reach the same as NR_IRQS.
  15  * In reality, the number of nested IRQS is limited to the stack
  16  * size as well. For archs with over 1000 IRQS it is not practical
  17  * to expect that they will all nest. We give a max of 10 bits for
  18  * hardirq nesting. An arch may choose to give less than 10 bits.
  19  * m68k expects it to be 8.
  20  *
  21  * - bits 16-25 are the hardirq count (max # of nested hardirqs: 1024)
  22  * - bit 26 is the NMI_MASK
  23  * - bit 27 is the PREEMPT_ACTIVE flag
  24  *
  25  * PREEMPT_MASK: 0x000000ff
  26  * SOFTIRQ_MASK: 0x0000ff00
  27  * HARDIRQ_MASK: 0x03ff0000
  28  *     NMI_MASK: 0x04000000
  29  */
  30 #define PREEMPT_BITS    8
  31 #define SOFTIRQ_BITS    8
  32 #define NMI_BITS        1
  33
  34 #define MAX_HARDIRQ_BITS 10
  35
  36 #ifndef HARDIRQ_BITS
  37 # define HARDIRQ_BITS   MAX_HARDIRQ_BITS
  38 #endif
  39
  40 #if HARDIRQ_BITS > MAX_HARDIRQ_BITS
  41 #error HARDIRQ_BITS too high!
  42 #endif
  43
  44 #define PREEMPT_SHIFT   0
  45 #define SOFTIRQ_SHIFT   (PREEMPT_SHIFT + PREEMPT_BITS)
  46 #define HARDIRQ_SHIFT   (SOFTIRQ_SHIFT + SOFTIRQ_BITS)
  47 #define NMI_SHIFT       (HARDIRQ_SHIFT + HARDIRQ_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 #define NMI_MASK        (__IRQ_MASK(NMI_BITS)     << NMI_SHIFT)
  55
  56 #define PREEMPT_OFFSET  (1UL << PREEMPT_SHIFT)
  57 #define SOFTIRQ_OFFSET  (1UL << SOFTIRQ_SHIFT)
  58 #define HARDIRQ_OFFSET  (1UL << HARDIRQ_SHIFT)
  59 #define NMI_OFFSET      (1UL << NMI_SHIFT)
  60
  61 #define SOFTIRQ_DISABLE_OFFSET  (2 * SOFTIRQ_OFFSET)
  62
  63 #ifndef PREEMPT_ACTIVE
  64 #define PREEMPT_ACTIVE_BITS     1
  65 #define PREEMPT_ACTIVE_SHIFT    (NMI_SHIFT + NMI_BITS)
  66 #define PREEMPT_ACTIVE  (__IRQ_MASK(PREEMPT_ACTIVE_BITS) << PREEMPT_ACTIVE_SHIFT)
  67 #endif
  68
  69 #if PREEMPT_ACTIVE < (1 << (NMI_SHIFT + NMI_BITS))
  70 #error PREEMPT_ACTIVE is too low!
  71 #endif
  72
  73 #define hardirq_count() (preempt_count() & HARDIRQ_MASK)
  74 #define softirq_count() (preempt_count() & SOFTIRQ_MASK)
  75 #define irq_count()     (preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK \
  76                                  | NMI_MASK))
  77
  78 /*
  79  * Are we doing bottom half or hardware interrupt processing?
  80  * Are we in a softirq context? Interrupt context?
  81  * in_softirq - Are we currently processing softirq or have bh disabled?
  82  * in_serving_softirq - Are we currently processing softirq?
  83  */
  84 #define in_irq()                (hardirq_count())
  85 #define in_softirq()            (softirq_count())
  86 #define in_interrupt()          (irq_count())
  87 #define in_serving_softirq()    (softirq_count() & SOFTIRQ_OFFSET)
  88
  89 /*
  90  * Are we in NMI context?
  91  */
  92 #define in_nmi()        (preempt_count() & NMI_MASK)
  93
  94 #if defined(CONFIG_PREEMPT_COUNT)
  95 # define PREEMPT_CHECK_OFFSET 1
  96 #else
  97 # define PREEMPT_CHECK_OFFSET 0
  98 #endif
  99
 100 /*
 101  * Are we running in atomic context?  WARNING: this macro cannot
 102  * always detect atomic context; in particular, it cannot know about
 103  * held spinlocks in non-preemptible kernels.  Thus it should not be
 104  * used in the general case to determine whether sleeping is possible.
 105  * Do not use in_atomic() in driver code.
 106  */
 107 #define in_atomic()     ((preempt_count() & ~PREEMPT_ACTIVE) != 0)
 108
 109 /*
 110  * Check whether we were atomic before we did preempt_disable():
 111  * (used by the scheduler, *after* releasing the kernel lock)
 112  */
 113 #define in_atomic_preempt_off() \
 114                 ((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_CHECK_OFFSET)
 115
 116 #ifdef CONFIG_PREEMPT_COUNT
 117 # define preemptible()  (preempt_count() == 0 && !irqs_disabled())
 118 #else
 119 # define preemptible()  0
 120 #endif
 121
 122 #endif /* LINUX_PREEMPT_MASK_H */