glibc/sysdeps/unix/sysv/linux/pthread_setaffinity.c
Florian Weimer 98734cc501 pthread_setaffinity (Linux variant): Rewrite to use VLA instead of alloca
extend_alloca was used to emulate VLA deallocation.  The new version
also handles the res == 0 corner case more explicitly, by returning 0
instead of the (potentially undefined, but usually zero) system call
error.
2015-03-23 16:34:48 +01:00

108 lines
2.9 KiB
C

/* Copyright (C) 2003-2015 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@redhat.com>, 2003.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <errno.h>
#include <pthreadP.h>
#include <sysdep.h>
#include <sys/types.h>
#include <shlib-compat.h>
size_t __kernel_cpumask_size attribute_hidden;
/* Determine the size of cpumask_t in the kernel. */
int
__determine_cpumask_size (pid_t tid)
{
size_t psize;
int res;
for (psize = 128; ; psize *= 2)
{
char buf[psize];
INTERNAL_SYSCALL_DECL (err);
res = INTERNAL_SYSCALL (sched_getaffinity, err, 3, tid, psize, buf);
if (INTERNAL_SYSCALL_ERROR_P (res, err))
{
if (INTERNAL_SYSCALL_ERRNO (res, err) != EINVAL)
return INTERNAL_SYSCALL_ERRNO (res, err);
}
else
break;
}
if (res != 0)
__kernel_cpumask_size = res;
return 0;
}
int
__pthread_setaffinity_new (pthread_t th, size_t cpusetsize,
const cpu_set_t *cpuset)
{
const struct pthread *pd = (const struct pthread *) th;
INTERNAL_SYSCALL_DECL (err);
int res;
if (__glibc_unlikely (__kernel_cpumask_size == 0))
{
res = __determine_cpumask_size (pd->tid);
if (res != 0)
return res;
}
/* We now know the size of the kernel cpumask_t. Make sure the user
does not request to set a bit beyond that. */
for (size_t cnt = __kernel_cpumask_size; cnt < cpusetsize; ++cnt)
if (((char *) cpuset)[cnt] != '\0')
/* Found a nonzero byte. This means the user request cannot be
fulfilled. */
return EINVAL;
res = INTERNAL_SYSCALL (sched_setaffinity, err, 3, pd->tid, cpusetsize,
cpuset);
#ifdef RESET_VGETCPU_CACHE
if (!INTERNAL_SYSCALL_ERROR_P (res, err))
RESET_VGETCPU_CACHE ();
#endif
return (INTERNAL_SYSCALL_ERROR_P (res, err)
? INTERNAL_SYSCALL_ERRNO (res, err)
: 0);
}
versioned_symbol (libpthread, __pthread_setaffinity_new,
pthread_setaffinity_np, GLIBC_2_3_4);
#if SHLIB_COMPAT (libpthread, GLIBC_2_3_3, GLIBC_2_3_4)
int
__pthread_setaffinity_old (pthread_t th, cpu_set_t *cpuset)
{
/* The old interface by default assumed a 1024 processor bitmap. */
return __pthread_setaffinity_new (th, 128, cpuset);
}
compat_symbol (libpthread, __pthread_setaffinity_old, pthread_setaffinity_np,
GLIBC_2_3_3);
#endif