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Re: PATCH: Make libmmalloc work properly with /dev/zero
- From: Andrew Cagney <ac131313 at cygnus dot com>
- To: Scott Pakin <pakin at uiuc dot edu>
- Cc: gdb-patches at sources dot redhat dot com
- Date: Sun, 07 Apr 2002 13:58:08 -0400
- Subject: Re: PATCH: Make libmmalloc work properly with /dev/zero
- References: <3C854268.2080508@uiuc.edu> <3C9CDD7A.1080302@cygnus.com> <3C9F64F9.6040908@uiuc.edu>
FYI,
I've checked in the attached. I tweaked the code and ChangeLog to
comply with GNU conventions (and resisted the temptation to change the
macro into a function :-).
thanks!
Andrew
2002-04-07 Andrew Cagney <ac131313@redhat.com>
From 2002-03-05 Scott Pakin <pakin@uiuc.edu>
* mmap-sup.c (MAP_PRIVATE_OR_SHARED): Define.
(__mmalloc_mmap_morecore): Use.
(__mmalloc_remap_core): Use.
Index: mmap-sup.c
===================================================================
RCS file: /cvs/src/src/mmalloc/mmap-sup.c,v
retrieving revision 1.3
diff -u -r1.3 mmap-sup.c
--- mmap-sup.c 19 Feb 2000 00:44:46 -0000 1.3
+++ mmap-sup.c 7 Apr 2002 17:53:23 -0000
@@ -48,6 +48,15 @@
#define PAGE_ALIGN(addr) (caddr_t) (((long)(addr) + pagesize - 1) & \
~(pagesize - 1))
+
+/* Return MAP_PRIVATE if MDP represents /dev/zero. Otherwise, return
+ MAP_SHARED. */
+
+#define MAP_PRIVATE_OR_SHARED(MDP) ((MDP -> flags & MMALLOC_DEVZERO) \
+ ? MAP_PRIVATE \
+ : MAP_SHARED)
+
+
/* Get core for the memory region specified by MDP, using SIZE as the
amount to either add to or subtract from the existing region. Works
like sbrk(), but using mmap(). */
@@ -113,7 +122,7 @@
{
/* Let mmap pick the map start address */
mapto = mmap (0, mapbytes, PROT_READ | PROT_WRITE,
- MAP_SHARED, mdp -> fd, foffset);
+ MAP_PRIVATE_OR_SHARED (mdp), mdp -> fd, foffset);
if (mapto != (caddr_t) -1)
{
mdp -> base = mdp -> breakval = mapto;
@@ -125,7 +134,8 @@
else
{
mapto = mmap (mdp -> top, mapbytes, PROT_READ | PROT_WRITE,
- MAP_SHARED | MAP_FIXED, mdp -> fd, foffset);
+ MAP_PRIVATE_OR_SHARED (mdp) | MAP_FIXED, mdp -> fd,
+ foffset);
if (mapto == mdp -> top)
{
mdp -> top = moveto;
@@ -152,7 +162,7 @@
/* FIXME: Quick hack, needs error checking and other attention. */
base = mmap (mdp -> base, mdp -> top - mdp -> base,
- PROT_READ | PROT_WRITE, MAP_SHARED | MAP_FIXED,
+ PROT_READ | PROT_WRITE, MAP_PRIVATE_OR_SHARED (mdp) | MAP_FIXED,
mdp -> fd, 0);
return ((PTR) base);
}
@@ -166,13 +176,13 @@
caddr_t base = NULL;
#ifdef MAP_ANONYMOUS
- flags = MAP_SHARED | MAP_ANONYMOUS;
+ flags = MAP_PRIVATE | MAP_ANONYMOUS;
fd = -1;
#else
#ifdef MAP_FILE
- flags = MAP_SHARED | MAP_FILE;
+ flags = MAP_PRIVATE | MAP_FILE;
#else
- flags = MAP_SHARED;
+ flags = MAP_PRIVATE;
#endif
fd = open ("/dev/zero", O_RDWR);
if (fd != -1)