liblttng-ust-comm/ust-cancelstate.c

   1 /*
   2  * SPDX-License-Identifier: LGPL-2.1-only
   3  *
   4  * Copyright (C) 2021 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  */
   6
   7 #include <pthread.h>
   8 #include <errno.h>
   9 #include <error.h>
  10 #include <urcu/tls-compat.h>
  11 #include <lttng/ust-cancelstate.h>
  12 #include <usterr-signal-safe.h>
  13
  14 struct ust_cancelstate {
  15         int nesting;
  16         int oldstate;   /* oldstate for outermost nesting */
  17 };
  18
  19 static DEFINE_URCU_TLS(struct ust_cancelstate, thread_state);
  20
  21 int lttng_ust_cancelstate_disable_push(void)
  22 {
  23         struct ust_cancelstate *state = &URCU_TLS(thread_state);
  24         int ret, oldstate;
  25
  26         if (state->nesting++)
  27                 goto end;
  28         ret = pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &oldstate);
  29         if (ret) {
  30                 ERR("pthread_setcancelstate: %s", strerror(ret));
  31                 return -1;
  32         }
  33         state->oldstate = oldstate;
  34 end:
  35         return 0;
  36 }
  37
  38 int lttng_ust_cancelstate_disable_pop(void)
  39 {
  40         struct ust_cancelstate *state = &URCU_TLS(thread_state);
  41         int ret, oldstate;
  42
  43         if (!state->nesting)
  44                 return -1;
  45         if (--state->nesting)
  46                 goto end;
  47         ret = pthread_setcancelstate(state->oldstate, &oldstate);
  48         if (ret) {
  49                 ERR("pthread_setcancelstate: %s", strerror(ret));
  50                 return -1;
  51         }
  52         if (oldstate != PTHREAD_CANCEL_DISABLE) {
  53                 ERR("pthread_setcancelstate: unexpected oldstate");
  54                 return -1;
  55         }
  56 end:
  57         return 0;
  58 }
  59
  60