LXR linux/tools/testing/selftests/rcutorture/formal/srcu-cbmc/src/preempt.c

   1#include <config.h>
   2
   3#include "preempt.h"
   4
   5#include "assume.h"
   6#include "locks.h"
   7
   8/* Support NR_CPUS of at most 64 */
   9#define CPU_PREEMPTION_LOCKS_INIT0 LOCK_IMPL_INITIALIZER
  10#define CPU_PREEMPTION_LOCKS_INIT1 \
  11        CPU_PREEMPTION_LOCKS_INIT0, CPU_PREEMPTION_LOCKS_INIT0
  12#define CPU_PREEMPTION_LOCKS_INIT2 \
  13        CPU_PREEMPTION_LOCKS_INIT1, CPU_PREEMPTION_LOCKS_INIT1
  14#define CPU_PREEMPTION_LOCKS_INIT3 \
  15        CPU_PREEMPTION_LOCKS_INIT2, CPU_PREEMPTION_LOCKS_INIT2
  16#define CPU_PREEMPTION_LOCKS_INIT4 \
  17        CPU_PREEMPTION_LOCKS_INIT3, CPU_PREEMPTION_LOCKS_INIT3
  18#define CPU_PREEMPTION_LOCKS_INIT5 \
  19        CPU_PREEMPTION_LOCKS_INIT4, CPU_PREEMPTION_LOCKS_INIT4
  20
  21/*
  22 * Simulate disabling preemption by locking a particular cpu. NR_CPUS
  23 * should be the actual number of cpus, not just the maximum.
  24 */
  25struct lock_impl cpu_preemption_locks[NR_CPUS] = {
  26        CPU_PREEMPTION_LOCKS_INIT0
  27#if (NR_CPUS - 1) & 1
  28        , CPU_PREEMPTION_LOCKS_INIT0
  29#endif
  30#if (NR_CPUS - 1) & 2
  31        , CPU_PREEMPTION_LOCKS_INIT1
  32#endif
  33#if (NR_CPUS - 1) & 4
  34        , CPU_PREEMPTION_LOCKS_INIT2
  35#endif
  36#if (NR_CPUS - 1) & 8
  37        , CPU_PREEMPTION_LOCKS_INIT3
  38#endif
  39#if (NR_CPUS - 1) & 16
  40        , CPU_PREEMPTION_LOCKS_INIT4
  41#endif
  42#if (NR_CPUS - 1) & 32
  43        , CPU_PREEMPTION_LOCKS_INIT5
  44#endif
  45};
  46
  47#undef CPU_PREEMPTION_LOCKS_INIT0
  48#undef CPU_PREEMPTION_LOCKS_INIT1
  49#undef CPU_PREEMPTION_LOCKS_INIT2
  50#undef CPU_PREEMPTION_LOCKS_INIT3
  51#undef CPU_PREEMPTION_LOCKS_INIT4
  52#undef CPU_PREEMPTION_LOCKS_INIT5
  53
  54__thread int thread_cpu_id;
  55__thread int preempt_disable_count;
  56
  57void preempt_disable(void)
  58{
  59        BUG_ON(preempt_disable_count < 0 || preempt_disable_count == INT_MAX);
  60
  61        if (preempt_disable_count++)
  62                return;
  63
  64        thread_cpu_id = nondet_int();
  65        assume(thread_cpu_id >= 0);
  66        assume(thread_cpu_id < NR_CPUS);
  67        lock_impl_lock(&cpu_preemption_locks[thread_cpu_id]);
  68}
  69
  70void preempt_enable(void)
  71{
  72        BUG_ON(preempt_disable_count < 1);
  73
  74        if (--preempt_disable_count)
  75                return;
  76
  77        lock_impl_unlock(&cpu_preemption_locks[thread_cpu_id]);
  78}
  79