Author: kib
Date: Sun Apr 30 19:32:51 2017
New Revision: 317610
URL: https://svnweb.freebsd.org/changeset/base/317610
Log:
Restructure normal (non-error) control flow in sem_close().
Do not retest for the found semaphore after the loop to look it up.
Instead, handle both cases of last and non-last close simultaneously,
which allows to consolidate the list unlock and successful return.
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Modified:
head/lib/libc/gen/sem_new.c
Modified: head/lib/libc/gen/sem_new.c
==============================================================================
--- head/lib/libc/gen/sem_new.c Sun Apr 30 18:39:31 2017 (r317609)
+++ head/lib/libc/gen/sem_new.c Sun Apr 30 19:32:51 2017 (r317610)
@@ -41,6 +41,7 @@
#include <fcntl.h>
#include <pthread.h>
#include <stdarg.h>
+#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
@@ -260,6 +261,7 @@ int
_sem_close(sem_t *sem)
{
struct sem_nameinfo *ni;
+ bool last;
if (sem_check_validity(sem) != 0)
return (-1);
@@ -274,21 +276,17 @@ _sem_close(sem_t *sem)
_pthread_mutex_lock(&sem_llock);
LIST_FOREACH(ni, &sem_list, next) {
if (sem == ni->sem) {
- if (--ni->open_count > 0) {
- _pthread_mutex_unlock(&sem_llock);
- return (0);
+ last = --ni->open_count == 0;
+ if (last)
+ LIST_REMOVE(ni, next);
+ _pthread_mutex_unlock(&sem_llock);
+ if (last) {
+ munmap(sem, sizeof(*sem));
+ free(ni);
}
- break;
+ return (0);
}
}
-
- if (ni != NULL) {
- LIST_REMOVE(ni, next);
- _pthread_mutex_unlock(&sem_llock);
- munmap(sem, sizeof(*sem));
- free(ni);
- return (0);
- }
_pthread_mutex_unlock(&sem_llock);
errno = EINVAL;
return (-1);
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