This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
[PATCH 04/25] sched_setaffinity (Linux variant): Rewrite to use VLA instead of alloca
- From: Florian Weimer <fweimer at redhat dot com>
- To: libc-alpha at sourceware dot org
- Date: Sun, 1 Mar 2015 15:05:41 +0100
- Subject: [PATCH 04/25] sched_setaffinity (Linux variant): Rewrite to use VLA instead of alloca
- Authentication-results: sourceware.org; auth=none
- References: <cover dot 1425285061 dot git dot fweimer at redhat dot com>
extend_alloca was used to emulate VLA deallocation.
---
sysdeps/unix/sysv/linux/sched_setaffinity.c | 37 ++++++++++++++++-------------
1 file changed, 20 insertions(+), 17 deletions(-)
diff --git a/sysdeps/unix/sysv/linux/sched_setaffinity.c b/sysdeps/unix/sysv/linux/sched_setaffinity.c
index b528617..a9299d8 100644
--- a/sysdeps/unix/sysv/linux/sched_setaffinity.c
+++ b/sysdeps/unix/sysv/linux/sched_setaffinity.c
@@ -22,7 +22,6 @@
#include <unistd.h>
#include <sys/types.h>
#include <shlib-compat.h>
-#include <alloca.h>
#ifdef __NR_sched_setaffinity
@@ -34,25 +33,29 @@ __sched_setaffinity_new (pid_t pid, size_t cpusetsize, const cpu_set_t *cpuset)
{
if (__glibc_unlikely (__kernel_cpumask_size == 0))
{
- INTERNAL_SYSCALL_DECL (err);
- int res;
-
size_t psize = 128;
- void *p = alloca (psize);
-
- while (res = INTERNAL_SYSCALL (sched_getaffinity, err, 3, getpid (),
- psize, p),
- INTERNAL_SYSCALL_ERROR_P (res, err)
- && INTERNAL_SYSCALL_ERRNO (res, err) == EINVAL)
- p = extend_alloca (p, psize, 2 * psize);
-
- if (res == 0 || INTERNAL_SYSCALL_ERROR_P (res, err))
+ while (1)
{
- __set_errno (INTERNAL_SYSCALL_ERRNO (res, err));
- return -1;
+ char buf[psize];
+ INTERNAL_SYSCALL_DECL (err);
+ int res = INTERNAL_SYSCALL (sched_getaffinity, err, 3, getpid (),
+ psize, buf);
+ if (INTERNAL_SYSCALL_ERROR_P (res, err)
+ && INTERNAL_SYSCALL_ERRNO (res, err) == EINVAL)
+ /* Retry with larger size. */
+ psize *= 2;
+ else if (res == 0 || INTERNAL_SYSCALL_ERROR_P (res, err))
+ {
+ __set_errno (INTERNAL_SYSCALL_ERRNO (res, err));
+ return -1;
+ }
+ else
+ {
+ /* Size has been determined. */
+ __kernel_cpumask_size = res;
+ break;
+ }
}
-
- __kernel_cpumask_size = res;
}
/* We now know the size of the kernel cpumask_t. Make sure the user
--
2.1.0