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pthread_setaffinity (Linux variant): Rewrite to use VLA instead of alloca

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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.
This commit is contained in:
Florian Weimer 2015-03-23 16:34:48 +01:00
parent 2b028564f1
commit 98734cc501
2 changed files with 23 additions and 14 deletions
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6
ChangeLog
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@ -1,3 +1,9 @@
2015-03-23 Florian Weimer <fweimer@redhat.com>
* sysdeps/unix/sysv/linux/pthread_setaffinity.c
(__determine_cpumask_size): Replace extend_alloca with a
variable-length array. Do not treat res == 0 as an error.
2015-03-23 Florian Weimer <fweimer@redhat.com>
[BZ #18100]

31
sysdeps/unix/sysv/linux/pthread_setaffinity.c
View File

@ -16,7 +16,6 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <alloca.h>
#include <errno.h>
#include <pthreadP.h>
#include <sysdep.h>
@ -27,26 +26,30 @@
size_t __kernel_cpumask_size attribute_hidden;
/* Determine the current affinity. As a side affect we learn
about the size of the cpumask_t in the kernel. */
/* Determine the size of cpumask_t in the kernel. */
int
__determine_cpumask_size (pid_t tid)
{
INTERNAL_SYSCALL_DECL (err);
size_t psize;
int res;
size_t psize = 128;
void *p = alloca (psize);
for (psize = 128; ; psize *= 2)
{
char buf[psize];
INTERNAL_SYSCALL_DECL (err);
while (res = INTERNAL_SYSCALL (sched_getaffinity, err, 3, tid, psize, p),
INTERNAL_SYSCALL_ERROR_P (res, err)
&& INTERNAL_SYSCALL_ERRNO (res, err) == EINVAL)
p = extend_alloca (p, psize, 2 * psize);
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 || INTERNAL_SYSCALL_ERROR_P (res, err))
return INTERNAL_SYSCALL_ERRNO (res, err);
__kernel_cpumask_size = res;
if (res != 0)
__kernel_cpumask_size = res;
return 0;
}