Sun Jan 24 17:29:11 2021 UTC ()
Add kmem_tmpbuf_alloc(), a utility function for allocating memory for
temporary use where allocation on the stack is desirable, but only up to
a certain size. If the requested size fits within the specified stack
buffer, the stack buffer is returned. Otherwise, memory is allocated with
kmem_alloc(). Add a corresponding kmem_tmpbuf_free() function that frees
the memory using kmem_free() if it is not the tempory stack buffer location.
(thorpej)
diff -r1.2372 -r1.2373 src/distrib/sets/lists/comp/mi
diff -r1.454 -r1.455 src/share/man/man9/Makefile
diff -r1.26 -r1.27 src/share/man/man9/kmem.9
diff -r1.80 -r1.81 src/sys/kern/subr_kmem.c
diff -r1.11 -r1.12 src/sys/sys/kmem.h
--- src/distrib/sets/lists/comp/mi 2021/01/21 15:53:15 1.2372
+++ src/distrib/sets/lists/comp/mi 2021/01/24 17:29:11 1.2373
@@ -1,4 +1,4 @@
-# $NetBSD: mi,v 1.2372 2021/01/21 15:53:15 thorpej Exp $
+# $NetBSD: mi,v 1.2373 2021/01/24 17:29:11 thorpej Exp $
#
# Note: don't delete entries from here - mark them as "obsolete" instead.
./etc/mtree/set.comp comp-sys-root
@@ -11650,6 +11650,8 @@
./usr/share/man/cat9/kmem_intr_zalloc.0 comp-sys-catman .cat
./usr/share/man/cat9/kmem_strdupsize.0 comp-sys-catman .cat
./usr/share/man/cat9/kmem_strfree.0 comp-sys-catman .cat
+./usr/share/man/cat9/kmem_tmpbuf_alloc.0 comp-sys-catman .cat
+./usr/share/man/cat9/kmem_tmpbuf_free.0 comp-sys-catman .cat
./usr/share/man/cat9/kmem_zalloc.0 comp-sys-catman .cat
./usr/share/man/cat9/knote.0 comp-sys-catman .cat
./usr/share/man/cat9/kpause.0 comp-sys-catman .cat
@@ -19815,6 +19817,8 @@
./usr/share/man/html9/kmem_intr_zalloc.html comp-sys-htmlman html
./usr/share/man/html9/kmem_strdupsize.html comp-sys-htmlman html
./usr/share/man/html9/kmem_strfree.html comp-sys-htmlman html
+./usr/share/man/html9/kmem_tmpbuf_alloc.html comp-sys-htmlman html
+./usr/share/man/html9/kmem_tmpbuf_free.html comp-sys-htmlman html
./usr/share/man/html9/kmem_zalloc.html comp-sys-htmlman html
./usr/share/man/html9/knote.html comp-sys-htmlman html
./usr/share/man/html9/kpause.html comp-sys-htmlman html
@@ -28132,6 +28136,8 @@
./usr/share/man/man9/kmem_intr_zalloc.9 comp-sys-man .man
./usr/share/man/man9/kmem_strdupsize.9 comp-sys-man .man
./usr/share/man/man9/kmem_strfree.9 comp-sys-man .man
+./usr/share/man/man9/kmem_tmpbuf_alloc.9 comp-sys-man .man
+./usr/share/man/man9/kmem_tmpbuf_free.9 comp-sys-man .man
./usr/share/man/man9/kmem_zalloc.9 comp-sys-man .man
./usr/share/man/man9/knote.9 comp-sys-man .man
./usr/share/man/man9/kpause.9 comp-sys-man .man
--- src/share/man/man9/Makefile 2021/01/21 15:53:16 1.454
+++ src/share/man/man9/Makefile 2021/01/24 17:29:11 1.455
@@ -1,4 +1,4 @@
-# $NetBSD: Makefile,v 1.454 2021/01/21 15:53:16 thorpej Exp $
+# $NetBSD: Makefile,v 1.455 2021/01/24 17:29:11 thorpej Exp $
# Makefile for section 9 (kernel function and variable) manual pages.
@@ -456,7 +456,9 @@
kmem.9 kmem_intr_zalloc.9 \
kmem.9 kmem_asprintf.9 \
kmem.9 kmem_strdupsize.9 \
- kmem.9 kmem_strfree.9
+ kmem.9 kmem_strfree.9 \
+ kmem.9 kmem_tmpbuf_alloc.9 \
+ kmem.9 kmem_tmpbuf_free.9
MAN+= kpreempt.9
MLINKS+=kpreempt.9 kpreempt_disable.9 \
kpreempt.9 kpreempt_disabled.9 \
--- src/share/man/man9/kmem.9 2020/06/19 07:25:20 1.26
+++ src/share/man/man9/kmem.9 2021/01/24 17:29:11 1.27
@@ -1,4 +1,4 @@
-.\" $NetBSD: kmem.9,v 1.26 2020/06/19 07:25:20 wiz Exp $
+.\" $NetBSD: kmem.9,v 1.27 2021/01/24 17:29:11 thorpej Exp $
.\"
.\" Copyright (c)2006 YAMAMOTO Takashi,
.\" All rights reserved.
@@ -25,7 +25,7 @@
.\" SUCH DAMAGE.
.\"
.\" ------------------------------------------------------------
-.Dd June 19, 2020
+.Dd January 24, 2021
.Dt KMEM 9
.Os
.\" ------------------------------------------------------------
@@ -73,6 +73,13 @@
.Fn kmem_strfree \
"char *str"
.\" ------------------------------------------------------------
+.Ft void *
+.Fn kmem_tmpbuf_alloc \
+"size_t size" "void *stackbuf" "size_t stackbufsize" "km_flag_t kmflags"
+.Ft void
+.Fn kmem_tmpbuf_free \
+"void *p" "size_t size" "void *stsackbuf"
+.\" ------------------------------------------------------------
.Pp
.Cd "options KMEM_SIZE"
.Sh DESCRIPTION
@@ -215,6 +222,23 @@
.Dv NUL
and then using
.Fn kmem_free .
+.Pp
+The
+.Fn kmem_tmpbuf_alloc
+function is a utility function for allocating memory for temporary
+use, where allocation on the stack is desirable, but only up to a
+certain size.
+If the requested size fits within the specified stack buffer, the
+stack buffer is returned.
+Otherwise, memory is allocated with
+.Fn kmem_alloc .
+The
+.Fn kmem_tmpbuf_free
+function compares the result of a previous call to
+.Fn kmem_tmpbuf_alloc
+and frees the memory using
+.Fn kmem_free
+if it is not the specified stack buffer.
.\" ------------------------------------------------------------
.Sh NOTES
Making
--- src/sys/kern/subr_kmem.c 2020/05/14 17:01:34 1.80
+++ src/sys/kern/subr_kmem.c 2021/01/24 17:29:11 1.81
@@ -1,4 +1,4 @@
-/* $NetBSD: subr_kmem.c,v 1.80 2020/05/14 17:01:34 maxv Exp $ */
+/* $NetBSD: subr_kmem.c,v 1.81 2021/01/24 17:29:11 thorpej Exp $ */
/*
* Copyright (c) 2009-2020 The NetBSD Foundation, Inc.
@@ -78,7 +78,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: subr_kmem.c,v 1.80 2020/05/14 17:01:34 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: subr_kmem.c,v 1.81 2021/01/24 17:29:11 thorpej Exp $");
#ifdef _KERNEL_OPT
#include "opt_kmem.h"
@@ -474,6 +474,29 @@
return;
kmem_free(str, strlen(str) + 1);
+}
+
+/*
+ * Utility routine to maybe-allocate a temporary buffer if the size
+ * is larger than we're willing to put on the stack.
+ */
+void *
+kmem_tmpbuf_alloc(size_t size, void *stackbuf, size_t stackbufsize,
+ km_flag_t flags)
+{
+ if (size <= stackbufsize) {
+ return stackbuf;
+ }
+
+ return kmem_alloc(size, flags);
+}
+
+void
+kmem_tmpbuf_free(void *buf, size_t size, void *stackbuf)
+{
+ if (buf != stackbuf) {
+ kmem_free(buf, size);
+ }
}
/* --------------------------- DEBUG / DIAGNOSTIC --------------------------- */
--- src/sys/sys/kmem.h 2018/01/09 01:53:55 1.11
+++ src/sys/sys/kmem.h 2021/01/24 17:29:11 1.12
@@ -1,4 +1,4 @@
-/* $NetBSD: kmem.h,v 1.11 2018/01/09 01:53:55 christos Exp $ */
+/* $NetBSD: kmem.h,v 1.12 2021/01/24 17:29:11 thorpej Exp $ */
/*-
* Copyright (c)2006 YAMAMOTO Takashi,
@@ -50,6 +50,9 @@
#define kmem_strdup(s, f) kmem_strdupsize((s), NULL, (f))
char * kmem_strndup(const char *, size_t, km_flag_t);
void kmem_strfree(char *);
+
+void * kmem_tmpbuf_alloc(size_t, void *, size_t, km_flag_t);
+void kmem_tmpbuf_free(void *, size_t, void *);
/*
* km_flag_t values: