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  */
  25 struct 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
  57 void 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
  70 void 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 }