libc/src/sched/linux/sched_rr_get_interval.cpp

   1 //===-- Implementation of sched_rr_get_interval ---------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "src/sched/sched_rr_get_interval.h"
  10
  11 #include "src/__support/OSUtil/syscall.h" // For internal syscall function.
  12 #include "src/__support/common.h"
  13 #include "src/errno/libc_errno.h"
  14
  15 #include <sys/syscall.h> // For syscall numbers.
  16
  17 #ifdef SYS_sched_rr_get_interval_time64
  18 #include <linux/time_types.h> // For __kernel_timespec.
  19 #endif
  20
  21 namespace LIBC_NAMESPACE {
  22
  23 LLVM_LIBC_FUNCTION(int, sched_rr_get_interval,
  24                    (pid_t tid, struct timespec *tp)) {
  25 #ifdef SYS_sched_rr_get_interval
  26   int ret =
  27       LIBC_NAMESPACE::syscall_impl<int>(SYS_sched_rr_get_interval, tid, tp);
  28 #elif defined(SYS_sched_rr_get_interval_time64)
  29   // The difference between the  and SYS_sched_rr_get_interval
  30   // SYS_sched_rr_get_interval_time64 syscalls is the data type used for the
  31   // time interval parameter: the latter takes a struct __kernel_timespec
  32   int ret;
  33   if (tp) {
  34     struct __kernel_timespec ts32;
  35     ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_sched_rr_get_interval_time64,
  36                                             tid, &ts32);
  37     if (ret == 0) {
  38       tp->tv_sec = ts32.tv_sec;
  39       tp->tv_nsec = ts32.tv_nsec;
  40     }
  41   } else
  42     // When tp is a nullptr, we still do the syscall to set ret and errno
  43     ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_sched_rr_get_interval_time64,
  44                                             tid, nullptr);
  45 #else
  46 #error                                                                         \
  47     "sched_rr_get_interval and sched_rr_get_interval_time64 syscalls not available."
  48 #endif
  49   if (ret < 0) {
  50     libc_errno = -ret;
  51     return -1;
  52   }
  53   return 0;
  54 }
  55
  56 } // namespace LIBC_NAMESPACE