liblttng-ust/lttng-clock.c

   1 /*
   2  * Copyright (C) 2014  Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; version 2.1 of
   7  * the License.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with this library; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
  17  */
  18
  19 #define _GNU_SOURCE
  20 #define _LGPL_SOURCE
  21 #include <error.h>
  22 #include <dlfcn.h>
  23 #include <stdlib.h>
  24 #include <usterr-signal-safe.h>
  25 #include <lttng/ust-clock.h>
  26 #include <urcu/system.h>
  27 #include <urcu/arch.h>
  28
  29 #include "clock.h"
  30 #include "getenv.h"
  31
  32 struct lttng_trace_clock *lttng_trace_clock;
  33
  34 static
  35 struct lttng_trace_clock user_tc;
  36
  37 static
  38 void *clock_handle;
  39
  40 int lttng_ust_trace_clock_set_read64_cb(uint64_t (*read64)(void))
  41 {
  42         if (CMM_LOAD_SHARED(lttng_trace_clock))
  43                 return -EBUSY;
  44         user_tc.read64 = read64;
  45         return 0;
  46 }
  47
  48 int lttng_ust_trace_clock_set_freq_cb(uint64_t (*freq)(void))
  49 {
  50         if (CMM_LOAD_SHARED(lttng_trace_clock))
  51                 return -EBUSY;
  52         user_tc.freq = freq;
  53         return 0;
  54 }
  55
  56 int lttng_ust_trace_clock_set_uuid_cb(int (*uuid)(char *uuid))
  57 {
  58         if (CMM_LOAD_SHARED(lttng_trace_clock))
  59                 return -EBUSY;
  60         user_tc.uuid = uuid;
  61         return 0;
  62 }
  63
  64 int lttng_ust_trace_clock_set_name_cb(const char *(*name)(void))
  65 {
  66         if (CMM_LOAD_SHARED(lttng_trace_clock))
  67                 return -EBUSY;
  68         user_tc.name = name;
  69         return 0;
  70 }
  71
  72 int lttng_ust_trace_clock_set_description_cb(const char *(*description)(void))
  73 {
  74         if (CMM_LOAD_SHARED(lttng_trace_clock))
  75                 return -EBUSY;
  76         user_tc.description = description;
  77         return 0;
  78 }
  79
  80 int lttng_ust_enable_trace_clock_override(void)
  81 {
  82         if (CMM_LOAD_SHARED(lttng_trace_clock))
  83                 return -EBUSY;
  84         if (!user_tc.read64)
  85                 return -EINVAL;
  86         if (!user_tc.freq)
  87                 return -EINVAL;
  88         if (!user_tc.name)
  89                 return -EINVAL;
  90         if (!user_tc.description)
  91                 return -EINVAL;
  92         /* Use default uuid cb when NULL */
  93         cmm_smp_mb();   /* Store callbacks before trace clock */
  94         CMM_STORE_SHARED(lttng_trace_clock, &user_tc);
  95         return 0;
  96 }
  97
  98 void lttng_ust_clock_init(void)
  99 {
 100         const char *libname;
 101         void (*libinit)(void);
 102
 103         if (clock_handle)
 104                 return;
 105         libname = lttng_getenv("LTTNG_UST_CLOCK_PLUGIN");
 106         if (!libname)
 107                 return;
 108         clock_handle = dlopen(libname, RTLD_NOW);
 109         if (!clock_handle) {
 110                 PERROR("Cannot load LTTng UST clock override library %s",
 111                         libname);
 112                 return;
 113         }
 114         dlerror();
 115         libinit = (void (*)(void)) dlsym(clock_handle,
 116                 "lttng_ust_clock_plugin_init");
 117         if (!libinit) {
 118                 PERROR("Cannot find LTTng UST clock override library %s initialization function lttng_ust_clock_plugin_init()",
 119                         libname);
 120                 return;
 121         }
 122         libinit();
 123 }