malloc: Use _int_free_chunk for remainders

When splitting a chunk, release the tail part by calling int_free_chunk.
This avoids inserting random blocks into tcache that were never requested
by the user.  Fragmentation will be worse if they are never used again.
Note if the tail is fairly small, we could avoid splitting it at all.
Also remove an oddly placed initialization of tcache in _libc_realloc.

Reviewed-by: DJ Delorie <dj@redhat.com>

diff --git a/malloc/malloc.c b/malloc/malloc.c
index b73ddbf554461da34d99258fae87c6ece6d175ba..0811061e4676d6d01f8906c05af6abc3b8489c38 100644 (file)
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -2646,7 +2646,7 @@ sysmalloc (INTERNAL_SIZE_T nb, mstate av)
                        CHUNK_HDR_SZ | PREV_INUSE);
               set_foot (chunk_at_offset (old_top, old_size), CHUNK_HDR_SZ);
               set_head (old_top, old_size | PREV_INUSE | NON_MAIN_ARENA);
-              _int_free (av, old_top, 1);
+              _int_free_chunk (av, old_top, chunksize (old_top), 1);
             }
           else
             {
@@ -2912,7 +2912,7 @@ sysmalloc (INTERNAL_SIZE_T nb, mstate av)
                       /* If possible, release the rest. */
                       if (old_size >= MINSIZE)
                         {
-                          _int_free (av, old_top, 1);
+                          _int_free_chunk (av, old_top, chunksize (old_top), 1);
                         }
                     }
                 }
@@ -3530,10 +3530,7 @@ __libc_realloc (void *oldmem, size_t bytes)
   if (chunk_is_mmapped (oldp))
     ar_ptr = NULL;
   else
-    {
-      MAYBE_INIT_TCACHE ();
-      ar_ptr = arena_for_chunk (oldp);
-    }
+    ar_ptr = arena_for_chunk (oldp);
 
   /* Little security check which won't hurt performance: the allocator
      never wraps around at the end of the address space.  Therefore
@@ -3608,7 +3605,7 @@ __libc_realloc (void *oldmem, size_t bytes)
          size_t sz = memsize (oldp);
          memcpy (newp, oldmem, sz);
          (void) tag_region (chunk2mem (oldp), sz);
-          _int_free (ar_ptr, oldp, 0);
+          _int_free_chunk (ar_ptr, oldp, chunksize (oldp), 0);
         }
     }
 
@@ -5059,7 +5056,7 @@ _int_realloc (mstate av, mchunkptr oldp, INTERNAL_SIZE_T oldsize,
              (void) tag_region (oldmem, sz);
              newmem = tag_new_usable (newmem);
              memcpy (newmem, oldmem, sz);
-             _int_free (av, oldp, 1);
+             _int_free_chunk (av, oldp, chunksize (oldp), 1);
              check_inuse_chunk (av, newp);
              return newmem;
             }
@@ -5087,7 +5084,7 @@ _int_realloc (mstate av, mchunkptr oldp, INTERNAL_SIZE_T oldsize,
                 (av != &main_arena ? NON_MAIN_ARENA : 0));
       /* Mark remainder as inuse so free() won't complain */
       set_inuse_bit_at_offset (remainder, remainder_size);
-      _int_free (av, remainder, 1);
+      _int_free_chunk (av, remainder, chunksize (remainder), 1);
     }
 
   check_inuse_chunk (av, newp);