Module Name: src
Committed By: rmind
Date: Mon Oct 5 23:46:02 UTC 2009
Modified Files:
src/sys/kern: sysv_sem.c
Log Message:
semu_alloc: simplify a little.
To generate a diff of this commit:
cvs rdiff -u -r1.85 -r1.86 src/sys/kern/sysv_sem.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/kern/sysv_sem.c
diff -u src/sys/kern/sysv_sem.c:1.85 src/sys/kern/sysv_sem.c:1.86
--- src/sys/kern/sysv_sem.c:1.85 Sun Jan 11 02:45:53 2009
+++ src/sys/kern/sysv_sem.c Mon Oct 5 23:46:02 2009
@@ -1,4 +1,4 @@
-/* $NetBSD: sysv_sem.c,v 1.85 2009/01/11 02:45:53 christos Exp $ */
+/* $NetBSD: sysv_sem.c,v 1.86 2009/10/05 23:46:02 rmind Exp $ */
/*-
* Copyright (c) 1999, 2007 The NetBSD Foundation, Inc.
@@ -39,7 +39,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: sysv_sem.c,v 1.85 2009/01/11 02:45:53 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: sysv_sem.c,v 1.86 2009/10/05 23:46:02 rmind Exp $");
#define SYSVSEM
@@ -279,72 +279,48 @@
}
/*
- * Allocate a new sem_undo structure for a process
- * (returns ptr to structure or NULL if no more room)
+ * Allocate a new sem_undo structure for a process.
+ * => Returns NULL on failure.
*/
-
struct sem_undo *
semu_alloc(struct proc *p)
{
+ struct sem_undo *suptr, **supptr;
+ bool attempted = false;
int i;
- struct sem_undo *suptr;
- struct sem_undo **supptr;
- int attempt;
KASSERT(mutex_owned(&semlock));
-
- /*
- * Try twice to allocate something.
- * (we'll purge any empty structures after the first pass so
- * two passes are always enough)
- */
-
- for (attempt = 0; attempt < 2; attempt++) {
- /*
- * Look for a free structure.
- * Fill it in and return it if we find one.
- */
-
- for (i = 0; i < seminfo.semmnu; i++) {
- suptr = SEMU(semu, i);
- if (suptr->un_proc == NULL) {
- suptr->un_next = semu_list;
- semu_list = suptr;
- suptr->un_cnt = 0;
- suptr->un_proc = p;
- return (suptr);
- }
+again:
+ /* Look for a free structure. */
+ for (i = 0; i < seminfo.semmnu; i++) {
+ suptr = SEMU(semu, i);
+ if (suptr->un_proc == NULL) {
+ /* Found. Fill it in and return. */
+ suptr->un_next = semu_list;
+ semu_list = suptr;
+ suptr->un_cnt = 0;
+ suptr->un_proc = p;
+ return suptr;
}
+ }
- /*
- * We didn't find a free one, if this is the first attempt
- * then try to free some structures.
- */
-
- if (attempt == 0) {
- /* All the structures are in use - try to free some */
- int did_something = 0;
-
- supptr = &semu_list;
- while ((suptr = *supptr) != NULL) {
- if (suptr->un_cnt == 0) {
- suptr->un_proc = NULL;
- *supptr = suptr->un_next;
- did_something = 1;
- } else
- supptr = &suptr->un_next;
+ /* Not found. Attempt to free some structures. */
+ if (!attempted) {
+ bool freed = false;
+
+ attempted = true;
+ supptr = &semu_list;
+ while ((suptr = *supptr) != NULL) {
+ if (suptr->un_cnt == 0) {
+ suptr->un_proc = NULL;
+ *supptr = suptr->un_next;
+ freed = true;
+ } else {
+ supptr = &suptr->un_next;
}
-
- /* If we didn't free anything then just give-up */
- if (!did_something)
- return (NULL);
- } else {
- /*
- * The second pass failed even though we freed
- * something after the first pass!
- * This is IMPOSSIBLE!
- */
- panic("semu_alloc - second attempt failed");
+ }
+ if (freed) {
+ goto again;
}
}
return NULL;
