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Restructure normal (non-error) control flow in sem_close().

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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
This commit is contained in:
Konstantin Belousov 2017-04-30 19:32:51 +00:00
parent c602f5f3f5
commit e6a183a40e
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=317610
1 changed files with 10 additions and 12 deletions
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22
lib/libc/gen/sem_new.c
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@ -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);