two changes which should improve realloc. first, fix zapcacheregion to

clear out the entire requested area, not just a perfect fit.  second,
use mquery to check for room to avoid getting an address we don't like
and having to send it back.

1 files changed, 19 insertions, 10 deletions

diff --git a/src/lib/libc/stdlib/malloc.c b/src/lib/libc/stdlib/malloc.c
index 92efd7d68b..7a48a0f2ff 100644
--- a/src/lib/libc/stdlib/malloc.c
+++ b/src/lib/libc/stdlib/malloc.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: malloc.c,v 1.143 2012/06/20 13:13:15 tedu Exp $       */
+/*      $OpenBSD: malloc.c,v 1.144 2012/06/22 01:30:17 tedu Exp $       */
 /*
  * Copyright (c) 2008 Otto Moerbeek <otto@drijf.net>
  *
@@ -94,6 +94,9 @@
 #define MMAPA(a,sz)     mmap((a), (size_t)(sz), PROT_READ | PROT_WRITE, \
     MAP_ANON | MAP_PRIVATE, -1, (off_t) 0)
 
+#define MQUERY(a, sz)   mquery((a), (size_t)(sz), PROT_READ | PROT_WRITE, \
+    MAP_ANON | MAP_PRIVATE, -1, (off_t)0)
+
 struct region_info {
         void *p;                /* page; low bits used to mark chunks */
         uintptr_t size;         /* size for pages, or chunk_info pointer */
@@ -356,7 +359,7 @@ unmap(struct dir_info *d, void *p, size_t sz)
 }
 
 static void
-zapcacheregion(struct dir_info *d, void *p)
+zapcacheregion(struct dir_info *d, void *p, size_t len)
 {
         u_int i;
         struct region_info *r;
@@ -364,7 +367,7 @@ zapcacheregion(struct dir_info *d, void *p)
 
         for (i = 0; i < mopts.malloc_cache; i++) {
                 r = &d->free_regions[i];
-                if (r->p == p) {
+                if (r->p >= p && r->p <= (void *)((char *)p + len)) {
                         rsz = r->size << MALLOC_PAGESHIFT;
                         if (munmap(r->p, rsz))
                                 wrterror("munmap", r->p);
@@ -1283,20 +1286,26 @@ orealloc(void *p, size_t newsz, void *f)
 
                 if (rnewsz > roldsz) {
                         if (!mopts.malloc_guard) {
+                                void *hint = (char *)p + roldsz;
+                                size_t needed = rnewsz - roldsz;
+
                                 STATS_INC(g_pool->cheap_realloc_tries);
-                                zapcacheregion(g_pool, (char *)p + roldsz);
-                                q = MMAPA((char *)p + roldsz, rnewsz - roldsz);
-                                if (q == (char *)p + roldsz) {
-                                        malloc_used += rnewsz - roldsz;
+                                zapcacheregion(g_pool, hint, needed);
+                                q = MQUERY(hint, needed);
+                                if (q == hint)
+                                        q = MMAPA(hint, needed);
+                                else
+                                        q = MAP_FAILED;
+                                if (q == hint) {
+                                        malloc_used += needed;
                                         if (mopts.malloc_junk)
-                                                memset(q, SOME_JUNK,
-                                                    rnewsz - roldsz);
+                                                memset(q, SOME_JUNK, needed);
                                         r->size = newsz;
                                         STATS_SETF(r, f);
                                         STATS_INC(g_pool->cheap_reallocs);
                                         return p;
                                 } else if (q != MAP_FAILED) {
-                                        if (munmap(q, rnewsz - roldsz))
+                                        if (munmap(q, needed))
                                                 wrterror("munmap", q);
                                 }
                         }