malloc/tst-memalign-2.c

   1 /* Test for memalign chunk reuse.
   2    Copyright (C) 2022 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <malloc.h>
  21 #include <stdio.h>
  22 #include <string.h>
  23 #include <unistd.h>
  24 #include <array_length.h>
  25 #include <libc-pointer-arith.h>
  26 #include <support/check.h>
  27
  28 typedef struct TestCase {
  29   size_t size;
  30   size_t alignment;
  31   void *ptr1;
  32   void *ptr2;
  33 } TestCase;
  34
  35 static TestCase tcache_allocs[] = {
  36   { 24, 32, NULL, NULL },
  37   { 24, 64, NULL, NULL },
  38   { 128, 128, NULL, NULL },
  39   { 500, 128, NULL, NULL }
  40 };
  41 #define TN array_length (tcache_allocs)
  42
  43 static TestCase large_allocs[] = {
  44   { 23450, 64, NULL, NULL },
  45   { 23450, 64, NULL, NULL },
  46   { 23550, 64, NULL, NULL },
  47   { 23550, 64, NULL, NULL },
  48   { 23650, 64, NULL, NULL },
  49   { 23650, 64, NULL, NULL },
  50   { 33650, 64, NULL, NULL },
  51   { 33650, 64, NULL, NULL }
  52 };
  53 #define LN array_length (large_allocs)
  54
  55 void *p;
  56
  57 /* Sanity checks, ancillary to the actual test.  */
  58 #define CHECK(p,a) \
  59   if (p == NULL || !PTR_IS_ALIGNED (p, a)) \
  60     FAIL_EXIT1 ("NULL or misaligned memory detected.\n");
  61
  62 static int
  63 do_test (void)
  64 {
  65   int i, j;
  66   int count;
  67   void *ptr[10];
  68   void *p;
  69
  70   /* TCache test.  */
  71
  72   for (i = 0; i < TN; ++ i)
  73     {
  74       size_t sz2;
  75
  76       tcache_allocs[i].ptr1 = memalign (tcache_allocs[i].alignment, tcache_allocs[i].size);
  77       CHECK (tcache_allocs[i].ptr1, tcache_allocs[i].alignment);
  78       sz2 = malloc_usable_size (tcache_allocs[i].ptr1);
  79       free (tcache_allocs[i].ptr1);
  80
  81       /* This should return the same chunk as was just free'd.  */
  82       tcache_allocs[i].ptr2 = memalign (tcache_allocs[i].alignment, sz2);
  83       CHECK (tcache_allocs[i].ptr2, tcache_allocs[i].alignment);
  84       free (tcache_allocs[i].ptr2);
  85
  86       TEST_VERIFY (tcache_allocs[i].ptr1 == tcache_allocs[i].ptr2);
  87     }
  88
  89   /* Test for non-head tcache hits.  This exercises the memalign
  90      scanning code to find matching allocations.  */
  91   for (i = 0; i < array_length (ptr); ++ i)
  92     {
  93       if (i == 4)
  94         {
  95           ptr[i] = memalign (64, 256);
  96           CHECK (ptr[i], 64);
  97         }
  98       else
  99         {
 100           ptr[i] = malloc (256);
 101           CHECK (ptr[i], 4);
 102         }
 103     }
 104   for (i = 0; i < array_length (ptr); ++ i)
 105     free (ptr[i]);
 106
 107   p = memalign (64, 256);
 108   CHECK (p, 64);
 109
 110   count = 0;
 111   for (i = 0; i < 10; ++ i)
 112     if (ptr[i] == p)
 113       ++ count;
 114   free (p);
 115   TEST_VERIFY (count > 0);
 116
 117   /* Large bins test.  This verifies that the over-allocated parts
 118      that memalign releases for future allocations can be reused by
 119      memalign itself at least in some cases.  */
 120
 121   for (i = 0; i < LN; ++ i)
 122     {
 123       large_allocs[i].ptr1 = memalign (large_allocs[i].alignment, large_allocs[i].size);
 124       CHECK (large_allocs[i].ptr1, large_allocs[i].alignment);
 125       /* Keep chunks from combining by fragmenting the heap.  */
 126       p = malloc (512);
 127       CHECK (p, 4);
 128     }
 129
 130   for (i = 0; i < LN; ++ i)
 131     free (large_allocs[i].ptr1);
 132
 133   /* Force the unsorted bins to be scanned and moved to small/large
 134      bins.  */
 135   p = malloc (60000);
 136
 137   for (i = 0; i < LN; ++ i)
 138     {
 139       large_allocs[i].ptr2 = memalign (large_allocs[i].alignment, large_allocs[i].size);
 140       CHECK (large_allocs[i].ptr2, large_allocs[i].alignment);
 141     }
 142
 143   count = 0;
 144   for (i = 0; i < LN; ++ i)
 145     {
 146       int ok = 0;
 147       for (j = 0; j < LN; ++ j)
 148         if (large_allocs[i].ptr1 == large_allocs[j].ptr2)
 149           ok = 1;
 150       if (ok == 1)
 151         count ++;
 152     }
 153
 154   /* The allocation algorithm is complicated outside of the memalign
 155      logic, so just make sure it's working for most of the
 156      allocations.  This avoids possible boundary conditions with
 157      empty/full heaps.  */
 158   TEST_VERIFY (count > LN / 2);
 159
 160   return 0;
 161 }
 162
 163 #include <support/test-driver.c>