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

DEFINITIONS

1. preempt_disable
2. preempt_enable

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <config.h>
   3 
   4 #include "preempt.h"
   5 
   6 #include "assume.h"
   7 #include "locks.h"
   8 
   9 /* Support NR_CPUS of at most 64 */
  10 #define CPU_PREEMPTION_LOCKS_INIT0 LOCK_IMPL_INITIALIZER
  11 #define CPU_PREEMPTION_LOCKS_INIT1 \
  12         CPU_PREEMPTION_LOCKS_INIT0, CPU_PREEMPTION_LOCKS_INIT0
  13 #define CPU_PREEMPTION_LOCKS_INIT2 \
  14         CPU_PREEMPTION_LOCKS_INIT1, CPU_PREEMPTION_LOCKS_INIT1
  15 #define CPU_PREEMPTION_LOCKS_INIT3 \
  16         CPU_PREEMPTION_LOCKS_INIT2, CPU_PREEMPTION_LOCKS_INIT2
  17 #define CPU_PREEMPTION_LOCKS_INIT4 \
  18         CPU_PREEMPTION_LOCKS_INIT3, CPU_PREEMPTION_LOCKS_INIT3
  19 #define CPU_PREEMPTION_LOCKS_INIT5 \
  20         CPU_PREEMPTION_LOCKS_INIT4, CPU_PREEMPTION_LOCKS_INIT4
  21 
  22 /*
  23  * Simulate disabling preemption by locking a particular cpu. NR_CPUS
  24  * should be the actual number of cpus, not just the maximum.
  25  */
  26 struct lock_impl cpu_preemption_locks[NR_CPUS] = {
  27         CPU_PREEMPTION_LOCKS_INIT0
  28 #if (NR_CPUS - 1) & 1
  29         , CPU_PREEMPTION_LOCKS_INIT0
  30 #endif
  31 #if (NR_CPUS - 1) & 2
  32         , CPU_PREEMPTION_LOCKS_INIT1
  33 #endif
  34 #if (NR_CPUS - 1) & 4
  35         , CPU_PREEMPTION_LOCKS_INIT2
  36 #endif
  37 #if (NR_CPUS - 1) & 8
  38         , CPU_PREEMPTION_LOCKS_INIT3
  39 #endif
  40 #if (NR_CPUS - 1) & 16
  41         , CPU_PREEMPTION_LOCKS_INIT4
  42 #endif
  43 #if (NR_CPUS - 1) & 32
  44         , CPU_PREEMPTION_LOCKS_INIT5
  45 #endif
  46 };
  47 
  48 #undef CPU_PREEMPTION_LOCKS_INIT0
  49 #undef CPU_PREEMPTION_LOCKS_INIT1
  50 #undef CPU_PREEMPTION_LOCKS_INIT2
  51 #undef CPU_PREEMPTION_LOCKS_INIT3
  52 #undef CPU_PREEMPTION_LOCKS_INIT4
  53 #undef CPU_PREEMPTION_LOCKS_INIT5
  54 
  55 __thread int thread_cpu_id;
  56 __thread int preempt_disable_count;
  57 
  58 void preempt_disable(void)
  59 {
  60         BUG_ON(preempt_disable_count < 0 || preempt_disable_count == INT_MAX);
  61 
  62         if (preempt_disable_count++)
  63                 return;
  64 
  65         thread_cpu_id = nondet_int();
  66         assume(thread_cpu_id >= 0);
  67         assume(thread_cpu_id < NR_CPUS);
  68         lock_impl_lock(&cpu_preemption_locks[thread_cpu_id]);
  69 }
  70 
  71 void preempt_enable(void)
  72 {
  73         BUG_ON(preempt_disable_count < 1);
  74 
  75         if (--preempt_disable_count)
  76                 return;
  77 
  78         lock_impl_unlock(&cpu_preemption_locks[thread_cpu_id]);
  79 }