source: asp3_tinet_ecnl_rx/trunk/musl-1.1.18/src/sched/sched_getcpu.c@ 337

#define _GNU_SOURCE
#include <errno.h>
#include <sched.h>
#include "syscall.h"
#include "atomic.h"

#ifdef VDSO_GETCPU_SYM

void *__vdsosym(const char *, const char *);

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;

#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) return cpu;
        return __syscall_ret(r);
}