ClickHouse/base/glibc-compatibility/musl/sched_getcpu.c
2021-01-29 19:11:50 +03:00

56 lines
1.1 KiB
C

#define _GNU_SOURCE
#include <errno.h>
#include <sched.h>
#include "syscall.h"
#include "atomic.h"
#if defined(__has_feature)
#if __has_feature(memory_sanitizer)
#include <sanitizer/msan_interface.h>
#endif
#endif
#ifdef VDSO_GETCPU_SYM
static void *volatile vdso_func;
typedef long (*getcpu_f)(unsigned *, unsigned *, void *);
static long getcpu_init(unsigned *cpu, unsigned *node, void *unused)
{
void *p = __vdsosym(VDSO_GETCPU_VER, VDSO_GETCPU_SYM);
getcpu_f f = (getcpu_f)p;
a_cas_p(&vdso_func, (void *)getcpu_init, p);
return f ? f(cpu, node, unused) : -ENOSYS;
}
static void *volatile vdso_func = (void *)getcpu_init;
#endif
int sched_getcpu(void)
{
int r;
unsigned cpu = 0;
#ifdef VDSO_GETCPU_SYM
getcpu_f f = (getcpu_f)vdso_func;
if (f) {
r = f(&cpu, 0, 0);
if (!r) return cpu;
if (r != -ENOSYS) return __syscall_ret(r);
}
#endif
r = __syscall(SYS_getcpu, &cpu, 0, 0);
if (!r) {
#if defined(__has_feature)
#if __has_feature(memory_sanitizer)
__msan_unpoison(&cpu, sizeof(cpu));
#endif
#endif
return cpu;
}
return __syscall_ret(r);
}