linux/include/linux/hardirq.h
<<
>>
Prefs
   1#ifndef LINUX_HARDIRQ_H
   2#define LINUX_HARDIRQ_H
   3
   4#include <linux/preempt.h>
   5#include <linux/lockdep.h>
   6#include <linux/ftrace_irq.h>
   7#include <asm/hardirq.h>
   8
   9/*
  10 * We put the hardirq and softirq counter into the preemption
  11 * counter. The bitmask has the following meaning:
  12 *
  13 * - bits 0-7 are the preemption count (max preemption depth: 256)
  14 * - bits 8-15 are the softirq count (max # of softirqs: 256)
  15 *
  16 * The hardirq count can in theory reach the same as NR_IRQS.
  17 * In reality, the number of nested IRQS is limited to the stack
  18 * size as well. For archs with over 1000 IRQS it is not practical
  19 * to expect that they will all nest. We give a max of 10 bits for
  20 * hardirq nesting. An arch may choose to give less than 10 bits.
  21 * m68k expects it to be 8.
  22 *
  23 * - bits 16-25 are the hardirq count (max # of nested hardirqs: 1024)
  24 * - bit 26 is the NMI_MASK
  25 * - bit 28 is the PREEMPT_ACTIVE flag
  26 *
  27 * PREEMPT_MASK: 0x000000ff
  28 * SOFTIRQ_MASK: 0x0000ff00
  29 * HARDIRQ_MASK: 0x03ff0000
  30 *     NMI_MASK: 0x04000000
  31 */
  32#define PREEMPT_BITS    8
  33#define SOFTIRQ_BITS    8
  34#define NMI_BITS        1
  35
  36#define MAX_HARDIRQ_BITS 10
  37
  38#ifndef HARDIRQ_BITS
  39# define HARDIRQ_BITS   MAX_HARDIRQ_BITS
  40#endif
  41
  42#if HARDIRQ_BITS > MAX_HARDIRQ_BITS
  43#error HARDIRQ_BITS too high!
  44#endif
  45
  46#define PREEMPT_SHIFT   0
  47#define SOFTIRQ_SHIFT   (PREEMPT_SHIFT + PREEMPT_BITS)
  48#define HARDIRQ_SHIFT   (SOFTIRQ_SHIFT + SOFTIRQ_BITS)
  49#define NMI_SHIFT       (HARDIRQ_SHIFT + HARDIRQ_BITS)
  50
  51#define __IRQ_MASK(x)   ((1UL << (x))-1)
  52
  53#define PREEMPT_MASK    (__IRQ_MASK(PREEMPT_BITS) << PREEMPT_SHIFT)
  54#define SOFTIRQ_MASK    (__IRQ_MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT)
  55#define HARDIRQ_MASK    (__IRQ_MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT)
  56#define NMI_MASK        (__IRQ_MASK(NMI_BITS)     << NMI_SHIFT)
  57
  58#define PREEMPT_OFFSET  (1UL << PREEMPT_SHIFT)
  59#define SOFTIRQ_OFFSET  (1UL << SOFTIRQ_SHIFT)
  60#define HARDIRQ_OFFSET  (1UL << HARDIRQ_SHIFT)
  61#define NMI_OFFSET      (1UL << NMI_SHIFT)
  62
  63#define SOFTIRQ_DISABLE_OFFSET  (2 * SOFTIRQ_OFFSET)
  64
  65#ifndef PREEMPT_ACTIVE
  66#define PREEMPT_ACTIVE_BITS     1
  67#define PREEMPT_ACTIVE_SHIFT    (NMI_SHIFT + NMI_BITS)
  68#define PREEMPT_ACTIVE  (__IRQ_MASK(PREEMPT_ACTIVE_BITS) << PREEMPT_ACTIVE_SHIFT)
  69#endif
  70
  71#if PREEMPT_ACTIVE < (1 << (NMI_SHIFT + NMI_BITS))
  72#error PREEMPT_ACTIVE is too low!
  73#endif
  74
  75#define hardirq_count() (preempt_count() & HARDIRQ_MASK)
  76#define softirq_count() (preempt_count() & SOFTIRQ_MASK)
  77#define irq_count()     (preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK \
  78                                 | NMI_MASK))
  79
  80/*
  81 * Are we doing bottom half or hardware interrupt processing?
  82 * Are we in a softirq context? Interrupt context?
  83 * in_softirq - Are we currently processing softirq or have bh disabled?
  84 * in_serving_softirq - Are we currently processing softirq?
  85 */
  86#define in_irq()                (hardirq_count())
  87#define in_softirq()            (softirq_count())
  88#define in_interrupt()          (irq_count())
  89#define in_serving_softirq()    (softirq_count() & SOFTIRQ_OFFSET)
  90
  91/*
  92 * Are we in NMI context?
  93 */
  94#define in_nmi()        (preempt_count() & NMI_MASK)
  95
  96#if defined(CONFIG_PREEMPT)
  97# define PREEMPT_CHECK_OFFSET 1
  98#else
  99# define PREEMPT_CHECK_OFFSET 0
 100#endif
 101
 102/*
 103 * Are we running in atomic context?  WARNING: this macro cannot
 104 * always detect atomic context; in particular, it cannot know about
 105 * held spinlocks in non-preemptible kernels.  Thus it should not be
 106 * used in the general case to determine whether sleeping is possible.
 107 * Do not use in_atomic() in driver code.
 108 */
 109#define in_atomic()     ((preempt_count() & ~PREEMPT_ACTIVE) != 0)
 110
 111/*
 112 * Check whether we were atomic before we did preempt_disable():
 113 * (used by the scheduler, *after* releasing the kernel lock)
 114 */
 115#define in_atomic_preempt_off() \
 116                ((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_CHECK_OFFSET)
 117
 118#ifdef CONFIG_PREEMPT
 119# define preemptible()  (preempt_count() == 0 && !irqs_disabled())
 120# define IRQ_EXIT_OFFSET (HARDIRQ_OFFSET-1)
 121#else
 122# define preemptible()  0
 123# define IRQ_EXIT_OFFSET HARDIRQ_OFFSET
 124#endif
 125
 126#if defined(CONFIG_SMP) || defined(CONFIG_GENERIC_HARDIRQS)
 127extern void synchronize_irq(unsigned int irq);
 128#else
 129# define synchronize_irq(irq)   barrier()
 130#endif
 131
 132struct task_struct;
 133
 134#if !defined(CONFIG_VIRT_CPU_ACCOUNTING) && !defined(CONFIG_IRQ_TIME_ACCOUNTING)
 135static inline void account_system_vtime(struct task_struct *tsk)
 136{
 137}
 138#else
 139extern void account_system_vtime(struct task_struct *tsk);
 140#endif
 141
 142#if defined(CONFIG_NO_HZ)
 143#if defined(CONFIG_TINY_RCU) || defined(CONFIG_TINY_PREEMPT_RCU)
 144extern void rcu_enter_nohz(void);
 145extern void rcu_exit_nohz(void);
 146
 147static inline void rcu_irq_enter(void)
 148{
 149        rcu_exit_nohz();
 150}
 151
 152static inline void rcu_irq_exit(void)
 153{
 154        rcu_enter_nohz();
 155}
 156
 157static inline void rcu_nmi_enter(void)
 158{
 159}
 160
 161static inline void rcu_nmi_exit(void)
 162{
 163}
 164
 165#else
 166extern void rcu_irq_enter(void);
 167extern void rcu_irq_exit(void);
 168extern void rcu_nmi_enter(void);
 169extern void rcu_nmi_exit(void);
 170#endif
 171#else
 172# define rcu_irq_enter() do { } while (0)
 173# define rcu_irq_exit() do { } while (0)
 174# define rcu_nmi_enter() do { } while (0)
 175# define rcu_nmi_exit() do { } while (0)
 176#endif /* #if defined(CONFIG_NO_HZ) */
 177
 178/*
 179 * It is safe to do non-atomic ops on ->hardirq_context,
 180 * because NMI handlers may not preempt and the ops are
 181 * always balanced, so the interrupted value of ->hardirq_context
 182 * will always be restored.
 183 */
 184#define __irq_enter()                                   \
 185        do {                                            \
 186                account_system_vtime(current);          \
 187                add_preempt_count(HARDIRQ_OFFSET);      \
 188                trace_hardirq_enter();                  \
 189        } while (0)
 190
 191/*
 192 * Enter irq context (on NO_HZ, update jiffies):
 193 */
 194extern void irq_enter(void);
 195
 196/*
 197 * Exit irq context without processing softirqs:
 198 */
 199#define __irq_exit()                                    \
 200        do {                                            \
 201                trace_hardirq_exit();                   \
 202                account_system_vtime(current);          \
 203                sub_preempt_count(HARDIRQ_OFFSET);      \
 204        } while (0)
 205
 206/*
 207 * Exit irq context and process softirqs if needed:
 208 */
 209extern void irq_exit(void);
 210
 211#define nmi_enter()                                             \
 212        do {                                                    \
 213                ftrace_nmi_enter();                             \
 214                BUG_ON(in_nmi());                               \
 215                add_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET); \
 216                lockdep_off();                                  \
 217                rcu_nmi_enter();                                \
 218                trace_hardirq_enter();                          \
 219        } while (0)
 220
 221#define nmi_exit()                                              \
 222        do {                                                    \
 223                trace_hardirq_exit();                           \
 224                rcu_nmi_exit();                                 \
 225                lockdep_on();                                   \
 226                BUG_ON(!in_nmi());                              \
 227                sub_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET); \
 228                ftrace_nmi_exit();                              \
 229        } while (0)
 230
 231#endif /* LINUX_HARDIRQ_H */
 232