Author: jh
Date: Mon Jul 5 16:23:55 2010
New Revision: 209710
URL: http://svn.freebsd.org/changeset/base/209710
Log:
Extend the kernel unit number allocator for allocating specific unit
numbers. This change adds a new function alloc_unr_specific() which
returns the requested unit number if it is free. If the number is
already allocated or out of the range, -1 is returned.
Update alloc_unr(9) manual page accordingly and add a MLINK for
alloc_unr_specific(9).
Discussed on: freebsd-hackers
Modified:
head/share/man/man9/Makefile
head/share/man/man9/alloc_unr.9
head/sys/kern/subr_unit.c
head/sys/sys/systm.h
Modified: head/share/man/man9/Makefile
==============================================================================
--- head/share/man/man9/Makefile Mon Jul 5 03:55:49 2010
(r209709)
+++ head/share/man/man9/Makefile Mon Jul 5 16:23:55 2010
(r209710)
@@ -374,6 +374,7 @@ MAN= accept_filter.9 \
zone.9
MLINKS= alloc_unr.9 alloc_unrl.9 \
+ alloc_unr.9 alloc_unr_specific.9 \
alloc_unr.9 delete_unrhdr.9 \
alloc_unr.9 free_unr.9 \
alloc_unr.9 new_unrhdr.9
Modified: head/share/man/man9/alloc_unr.9
==============================================================================
--- head/share/man/man9/alloc_unr.9 Mon Jul 5 03:55:49 2010
(r209709)
+++ head/share/man/man9/alloc_unr.9 Mon Jul 5 16:23:55 2010
(r209710)
@@ -24,13 +24,14 @@
.\"
.\" $FreeBSD$
.\"
-.Dd February 7, 2010
+.Dd July 5, 2010
.Dt ALLOC_UNR 9
.Os
.Sh NAME
.Nm new_unrhdr ,
.Nm delete_unrhdr ,
.Nm alloc_unr ,
+.Nm alloc_unr_specific ,
.Nm free_unr
.Nd "kernel unit number allocator"
.Sh SYNOPSIS
@@ -43,6 +44,8 @@
.Fn alloc_unr "struct unrhdr *uh"
.Ft int
.Fn alloc_unrl "struct unrhdr *uh"
+.Ft int
+.Fn alloc_unr_specific "struct unrhdr *uh" "u_int item"
.Ft void
.Fn free_unr "struct unrhdr *uh" "u_int item"
.Sh DESCRIPTION
@@ -81,6 +84,13 @@ is returned.
Same as
.Fn alloc_unr
except that mutex is assumed to be already locked and thus is not used.
+.It Fn alloc_unr_specific uh item
+Allocate a specific unit number.
+This function allocates memory and thus may sleep.
+The allocated unit number is returned on success.
+If the specified number is already allocated or out of the range,
+.Li \-1
+is returned.
.It Fn free_unr uh item
Free a previously allocated unit number.
This function may require allocating memory, and thus it can sleep.
Modified: head/sys/kern/subr_unit.c
==============================================================================
--- head/sys/kern/subr_unit.c Mon Jul 5 03:55:49 2010 (r209709)
+++ head/sys/kern/subr_unit.c Mon Jul 5 16:23:55 2010 (r209710)
@@ -628,6 +628,132 @@ alloc_unr(struct unrhdr *uh)
return (i);
}
+static int
+alloc_unr_specificl(struct unrhdr *uh, u_int item, void **p1, void **p2)
+{
+ struct unr *up, *upn;
+ struct unrb *ub;
+ u_int i, last, tl;
+
+ mtx_assert(uh->mtx, MA_OWNED);
+
+ if (item < uh->low + uh->first || item > uh->high)
+ return (-1);
+
+ up = TAILQ_FIRST(&uh->head);
+ /* Ideal split. */
+ if (up == NULL && item - uh->low == uh->first) {
+ uh->first++;
+ uh->last--;
+ uh->busy++;
+ check_unrhdr(uh, __LINE__);
+ return (item);
+ }
+
+ i = item - uh->low - uh->first;
+
+ if (up == NULL) {
+ up = new_unr(uh, p1, p2);
+ up->ptr = NULL;
+ up->len = i;
+ TAILQ_INSERT_TAIL(&uh->head, up, list);
+ up = new_unr(uh, p1, p2);
+ up->ptr = uh;
+ up->len = 1;
+ TAILQ_INSERT_TAIL(&uh->head, up, list);
+ uh->last = uh->high - uh->low - i;
+ uh->busy++;
+ check_unrhdr(uh, __LINE__);
+ return (item);
+ } else {
+ /* Find the item which contains the unit we want to allocate. */
+ TAILQ_FOREACH(up, &uh->head, list) {
+ if (up->len > i)
+ break;
+ i -= up->len;
+ }
+ }
+
+ if (up == NULL) {
+ if (i > 0) {
+ up = new_unr(uh, p1, p2);
+ up->ptr = NULL;
+ up->len = i;
+ TAILQ_INSERT_TAIL(&uh->head, up, list);
+ }
+ up = new_unr(uh, p1, p2);
+ up->ptr = uh;
+ up->len = 1;
+ TAILQ_INSERT_TAIL(&uh->head, up, list);
+ goto done;
+ }
+
+ if (is_bitmap(uh, up)) {
+ ub = up->ptr;
+ if (bit_test(ub->map, i) == 0) {
+ bit_set(ub->map, i);
+ ub->busy++;
+ goto done;
+ } else
+ return (-1);
+ } else if (up->ptr == uh)
+ return (-1);
+
+ KASSERT(up->ptr == NULL,
+ ("alloc_unr_specificl: up->ptr != NULL (up=%p)", up));
+
+ /* Split off the tail end, if any. */
+ tl = up->len - (1 + i);
+ if (tl > 0) {
+ upn = new_unr(uh, p1, p2);
+ upn->ptr = NULL;
+ upn->len = tl;
+ TAILQ_INSERT_AFTER(&uh->head, up, upn, list);
+ }
+
+ /* Split off head end, if any */
+ if (i > 0) {
+ upn = new_unr(uh, p1, p2);
+ upn->len = i;
+ upn->ptr = NULL;
+ TAILQ_INSERT_BEFORE(up, upn, list);
+ }
+ up->len = 1;
+ up->ptr = uh;
+
+done:
+ last = uh->high - uh->low - (item - uh->low);
+ if (uh->last > last)
+ uh->last = last;
+ uh->busy++;
+ collapse_unr(uh, up);
+ check_unrhdr(uh, __LINE__);
+ return (item);
+}
+
+int
+alloc_unr_specific(struct unrhdr *uh, u_int item)
+{
+ void *p1, *p2;
+ int i;
+
+ WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, "alloc_unr_specific");
+
+ p1 = Malloc(sizeof(struct unr));
+ p2 = Malloc(sizeof(struct unr));
+
+ mtx_lock(uh->mtx);
+ i = alloc_unr_specificl(uh, item, &p1, &p2);
+ mtx_unlock(uh->mtx);
+
+ if (p1 != NULL)
+ Free(p1);
+ if (p2 != NULL)
+ Free(p2);
+
+ return (i);
+}
+
/*
* Free a unr.
*
@@ -810,6 +936,42 @@ print_unrhdr(struct unrhdr *uh)
}
}
+static void
+test_alloc_unr(struct unrhdr *uh, u_int i, char a[])
+{
+ int j;
+
+ if (a[i]) {
+ printf("F %u\n", i);
+ free_unr(uh, i);
+ a[i] = 0;
+ } else {
+ no_alloc = 1;
+ j = alloc_unr(uh);
+ if (j != -1) {
+ a[j] = 1;
+ printf("A %d\n", j);
+ }
+ no_alloc = 0;
+ }
+}
+
+static void
+test_alloc_unr_specific(struct unrhdr *uh, u_int i, char a[])
+{
+ int j;
+
+ j = alloc_unr_specific(uh, i);
+ if (j == -1) {
+ printf("F %u\n", i);
+ a[i] = 0;
+ free_unr(uh, i);
+ } else {
+ a[i] = 1;
+ printf("A %d\n", j);
+ }
+}
+
/* Number of unrs to test */
#define NN 10000
@@ -825,6 +987,7 @@ main(int argc __unused, const char **arg
print_unrhdr(uh);
memset(a, 0, sizeof a);
+ srandomdev();
fprintf(stderr, "sizeof(struct unr) %zu\n", sizeof(struct unr));
fprintf(stderr, "sizeof(struct unrb) %zu\n", sizeof(struct unrb));
@@ -838,19 +1001,11 @@ main(int argc __unused, const char **arg
if (a[i] && (j & 1))
continue;
#endif
- if (a[i]) {
- printf("F %u\n", i);
- free_unr(uh, i);
- a[i] = 0;
- } else {
- no_alloc = 1;
- i = alloc_unr(uh);
- if (i != -1) {
- a[i] = 1;
- printf("A %u\n", i);
- }
- no_alloc = 0;
- }
+ if ((random() & 1) != 0)
+ test_alloc_unr(uh, i, a);
+ else
+ test_alloc_unr_specific(uh, i, a);
+
if (1) /* XXX: change this for detailed debug printout */
print_unrhdr(uh);
check_unrhdr(uh, __LINE__);
Modified: head/sys/sys/systm.h
==============================================================================
--- head/sys/sys/systm.h Mon Jul 5 03:55:49 2010 (r209709)
+++ head/sys/sys/systm.h Mon Jul 5 16:23:55 2010 (r209710)
@@ -363,6 +363,7 @@ void delete_unrhdr(struct unrhdr *uh);
void clean_unrhdr(struct unrhdr *uh);
void clean_unrhdrl(struct unrhdr *uh);
int alloc_unr(struct unrhdr *uh);
+int alloc_unr_specific(struct unrhdr *uh, u_int item);
int alloc_unrl(struct unrhdr *uh);
void free_unr(struct unrhdr *uh, u_int item);
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