src/bin/lttng-sessiond/fd-limit.cpp

   1 /*
   2  * Copyright (C) 2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   3  *
   4  * SPDX-License-Identifier: GPL-2.0-only
   5  *
   6  */
   7
   8 #define _LGPL_SOURCE
   9 #include <urcu/uatomic.h>
  10 #include <sys/time.h>
  11 #include <sys/resource.h>
  12 #include <stdio.h>
  13 #include "fd-limit.hpp"
  14 #include <common/error.hpp>
  15 #include <common/compat/errno.hpp>
  16
  17 /* total count of fd. */
  18 static long fd_count;
  19
  20 /*
  21  * threshold in % of number of fd allowed.
  22  */
  23 static long fd_threshold[LTTNG_FD_NR_TYPES] = {
  24         75, /* LTTNG_FD_APPS */
  25 };
  26
  27 static rlim_t max_nr_fd;
  28
  29 int lttng_fd_get(enum lttng_fd_type type, unsigned int nr)
  30 {
  31         long newval;
  32
  33         if (type >= LTTNG_FD_NR_TYPES) {
  34                 return -EINVAL;
  35         }
  36
  37         newval = uatomic_add_return(&fd_count, (long) nr);
  38         if ((long) (newval * 100)
  39                         - (long) (max_nr_fd * fd_threshold[type]) > 0) {
  40                 uatomic_sub(&fd_count, (long) nr);
  41                 return -EPERM;
  42         }
  43         return 0;
  44 }
  45
  46 void lttng_fd_put(enum lttng_fd_type type __attribute__((unused)),
  47                 unsigned int nr)
  48 {
  49         uatomic_sub(&fd_count, (long) nr);
  50 }
  51
  52 void lttng_fd_init(void)
  53 {
  54         struct rlimit rlim;
  55         int ret;
  56
  57         ret = getrlimit(RLIMIT_NOFILE, &rlim);
  58         if (ret < 0) {
  59                 PERROR("getrlimit");
  60         }
  61         max_nr_fd = rlim.rlim_cur;
  62 }