liblttng-ust/lttng-getcpu.c

   1 /*
   2  * SPDX-License-Identifier: LGPL-2.1-only
   3  *
   4  * Copyright (C) 2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  */
   6
   7 #define _LGPL_SOURCE
   8 #include <error.h>
   9 #include <dlfcn.h>
  10 #include <stdlib.h>
  11 #include <usterr-signal-safe.h>
  12 #include <lttng/ust-getcpu.h>
  13 #include <urcu/system.h>
  14 #include <urcu/arch.h>
  15
  16 #include "getenv.h"
  17 #include "../libringbuffer/getcpu.h"
  18
  19 int (*lttng_get_cpu)(void);
  20
  21 static
  22 void *getcpu_handle;
  23
  24 int lttng_ust_getcpu_override(int (*getcpu)(void))
  25 {
  26         CMM_STORE_SHARED(lttng_get_cpu, getcpu);
  27         return 0;
  28 }
  29
  30 void lttng_ust_getcpu_init(void)
  31 {
  32         const char *libname;
  33         void (*libinit)(void);
  34
  35         if (getcpu_handle)
  36                 return;
  37         libname = lttng_getenv("LTTNG_UST_GETCPU_PLUGIN");
  38         if (!libname)
  39                 return;
  40         getcpu_handle = dlopen(libname, RTLD_NOW);
  41         if (!getcpu_handle) {
  42                 PERROR("Cannot load LTTng UST getcpu override library %s",
  43                         libname);
  44                 return;
  45         }
  46         dlerror();
  47         libinit = (void (*)(void)) dlsym(getcpu_handle,
  48                 "lttng_ust_getcpu_plugin_init");
  49         if (!libinit) {
  50                 PERROR("Cannot find LTTng UST getcpu override library %s initialization function lttng_ust_getcpu_plugin_init()",
  51                         libname);
  52                 return;
  53         }
  54         libinit();
  55 }