module/splat/splat-linux.c

   1 /*****************************************************************************\
   2  *  Copyright (C) 2011 Lawrence Livermore National Security, LLC.
   3  *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
   4  *  Written by Brian Behlendorf <behlendorf1@llnl.gov>.
   5  *  UCRL-CODE-235197
   6  *
   7  *  This file is part of the SPL, Solaris Porting Layer.
   8  *  For details, see <http://zfsonlinux.org/>.
   9  *
  10  *  The SPL is free software; you can redistribute it and/or modify it
  11  *  under the terms of the GNU General Public License as published by the
  12  *  Free Software Foundation; either version 2 of the License, or (at your
  13  *  option) any later version.
  14  *
  15  *  The SPL is distributed in the hope that it will be useful, but WITHOUT
  16  *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  17  *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  18  *  for more details.
  19  *
  20  *  You should have received a copy of the GNU General Public License along
  21  *  with the SPL.  If not, see <http://www.gnu.org/licenses/>.
  22  *****************************************************************************
  23  *  Solaris Porting LAyer Tests (SPLAT) Kernel Compatibility Tests.
  24 \*****************************************************************************/
  25
  26 #include <sys/kmem.h>
  27 #include "splat-internal.h"
  28
  29 #define SPLAT_LINUX_NAME                "linux"
  30 #define SPLAT_LINUX_DESC                "Kernel Compatibility Tests"
  31
  32 #define SPLAT_LINUX_TEST1_ID            0x1001
  33 #define SPLAT_LINUX_TEST1_NAME          "shrinker"
  34 #define SPLAT_LINUX_TEST1_DESC          "Shrinker test"
  35
  36 /*
  37  * Wait queue used to eliminate race between dropping of slab
  38  * and execution of the shrinker callback
  39  */
  40 DECLARE_WAIT_QUEUE_HEAD(shrinker_wait);
  41
  42 SPL_SHRINKER_CALLBACK_FWD_DECLARE(splat_linux_shrinker_fn);
  43 SPL_SHRINKER_DECLARE(splat_linux_shrinker, splat_linux_shrinker_fn, 1);
  44 static unsigned long splat_linux_shrinker_size = 0;
  45 static struct file *splat_linux_shrinker_file = NULL;
  46
  47 static spl_shrinker_t
  48 __splat_linux_shrinker_fn(struct shrinker *shrink, struct shrink_control *sc)
  49 {
  50         static int failsafe = 0;
  51         static unsigned long last_splat_linux_shrinker_size = 0;
  52         unsigned long size;
  53         spl_shrinker_t count;
  54
  55         /*
  56          * shrinker_size can only decrease or stay the same between callbacks
  57          * in the same run, so Reset failsafe whenever shrinker increases
  58          * as this indicates a new run.
  59          */
  60         if (last_splat_linux_shrinker_size < splat_linux_shrinker_size)
  61                 failsafe = 0;
  62
  63         last_splat_linux_shrinker_size = splat_linux_shrinker_size;
  64
  65         if (sc->nr_to_scan) {
  66                 size = MIN(sc->nr_to_scan, splat_linux_shrinker_size);
  67                 splat_linux_shrinker_size -= size;
  68
  69                 splat_vprint(splat_linux_shrinker_file, SPLAT_LINUX_TEST1_NAME,
  70                     "Reclaimed %lu objects, size now %lu\n",
  71                     size, splat_linux_shrinker_size);
  72
  73 #ifdef HAVE_SPLIT_SHRINKER_CALLBACK
  74                 count = size;
  75 #else
  76                 count = splat_linux_shrinker_size;
  77 #endif /* HAVE_SPLIT_SHRINKER_CALLBACK */
  78
  79         } else {
  80                 count = splat_linux_shrinker_size;
  81                 splat_vprint(splat_linux_shrinker_file, SPLAT_LINUX_TEST1_NAME,
  82                     "Cache size is %lu\n", splat_linux_shrinker_size);
  83         }
  84
  85         /* Far more calls than expected abort drop_slab as a failsafe */
  86         if (failsafe > 100) {
  87                 splat_vprint(splat_linux_shrinker_file, SPLAT_LINUX_TEST1_NAME,
  88                     "Far more calls than expected (%d), size now %lu\n",
  89                    failsafe, splat_linux_shrinker_size);
  90                 return (SHRINK_STOP);
  91         } else {
  92                 /*
  93                  * We only increment failsafe if it doesn't trigger.  This
  94                  * makes any failsafe failure persistent until the next test.
  95                  */
  96                 failsafe++;
  97         }
  98
  99         /* Shrinker has run, so signal back to test. */
 100         wake_up(&shrinker_wait);
 101
 102         return (count);
 103 }
 104
 105 SPL_SHRINKER_CALLBACK_WRAPPER(splat_linux_shrinker_fn);
 106
 107 #define DROP_SLAB_CMD \
 108         "exec 0</dev/null " \
 109         "     1>/proc/sys/vm/drop_caches " \
 110         "     2>/dev/null; " \
 111         "echo 2"
 112
 113 static int
 114 splat_linux_drop_slab(struct file *file)
 115 {
 116         char *argv[] = { "/bin/sh",
 117                          "-c",
 118                          DROP_SLAB_CMD,
 119                          NULL };
 120         char *envp[] = { "HOME=/",
 121                          "TERM=linux",
 122                          "PATH=/sbin:/usr/sbin:/bin:/usr/bin",
 123                          NULL };
 124         int rc;
 125
 126         rc = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC);
 127         if (rc)
 128                 splat_vprint(file, SPLAT_LINUX_TEST1_NAME,
 129                     "Failed user helper '%s %s %s', rc = %d\n",
 130                     argv[0], argv[1], argv[2], rc);
 131
 132         return rc;
 133 }
 134
 135 /*
 136  * Verify correct shrinker functionality by registering a shrinker
 137  * with the required compatibility macros.  We then use a simulated
 138  * cache and force the systems caches to be dropped.  The shrinker
 139  * should be repeatedly called until it reports that the cache is
 140  * empty.  It is then cleanly unregistered and correct behavior is
 141  * verified.  There are now four slightly different supported shrinker
 142  * API and this test ensures the compatibility code is correct.
 143  */
 144 static int
 145 splat_linux_test1(struct file *file, void *arg)
 146 {
 147         int rc = -EINVAL;
 148
 149         /*
 150          * Globals used by the shrinker, it is not safe to run this
 151          * test concurrently this is a safe assumption for SPLAT tests.
 152          * Regardless we do some minimal checking a bail if concurrent
 153          * use is detected.
 154          */
 155         if (splat_linux_shrinker_size || splat_linux_shrinker_file) {
 156                 splat_vprint(file, SPLAT_LINUX_TEST1_NAME,
 157                     "Failed due to concurrent shrinker test, rc = %d\n", rc);
 158                 return (rc);
 159         }
 160
 161         splat_linux_shrinker_size = 1024;
 162         splat_linux_shrinker_file = file;
 163
 164         spl_register_shrinker(&splat_linux_shrinker);
 165         rc = splat_linux_drop_slab(file);
 166         if (rc)
 167                 goto out;
 168
 169         /*
 170          * By the time we get here, it is possible that the shrinker has not
 171          * yet run. splat_linux_drop_slab sends a signal for it to run, but
 172          * there is no guarantee of when it will actually run. We wait for it
 173          * to run here, terminating when either the shrinker size is now 0 or
 174          * we timeout after 1 second, which should be an eternity (error).
 175          */
 176         rc = wait_event_timeout(shrinker_wait, !splat_linux_shrinker_size, HZ);
 177         if (!rc) {
 178                 splat_vprint(file, SPLAT_LINUX_TEST1_NAME,
 179                     "Failed cache shrinking timed out, size now %lu",
 180                     splat_linux_shrinker_size);
 181                 rc = -ETIMEDOUT;
 182         } else {
 183                 rc = 0;
 184         }
 185
 186         if (!rc && splat_linux_shrinker_size != 0) {
 187                 splat_vprint(file, SPLAT_LINUX_TEST1_NAME,
 188                     "Failed cache was not shrunk to 0, size now %lu",
 189                     splat_linux_shrinker_size);
 190                 rc = -EDOM;
 191         }
 192 out:
 193         spl_unregister_shrinker(&splat_linux_shrinker);
 194
 195         splat_linux_shrinker_size = 0;
 196         splat_linux_shrinker_file = NULL;
 197
 198         return rc;
 199 }
 200
 201 splat_subsystem_t *
 202 splat_linux_init(void)
 203 {
 204         splat_subsystem_t *sub;
 205
 206         sub = kmalloc(sizeof(*sub), GFP_KERNEL);
 207         if (sub == NULL)
 208                 return NULL;
 209
 210         memset(sub, 0, sizeof(*sub));
 211         strncpy(sub->desc.name, SPLAT_LINUX_NAME, SPLAT_NAME_SIZE);
 212         strncpy(sub->desc.desc, SPLAT_LINUX_DESC, SPLAT_DESC_SIZE);
 213         INIT_LIST_HEAD(&sub->subsystem_list);
 214         INIT_LIST_HEAD(&sub->test_list);
 215         spin_lock_init(&sub->test_lock);
 216         sub->desc.id = SPLAT_SUBSYSTEM_LINUX;
 217
 218         SPLAT_TEST_INIT(sub, SPLAT_LINUX_TEST1_NAME, SPLAT_LINUX_TEST1_DESC,
 219                         SPLAT_LINUX_TEST1_ID, splat_linux_test1);
 220
 221         return sub;
 222 }
 223
 224 void
 225 splat_linux_fini(splat_subsystem_t *sub)
 226 {
 227         ASSERT(sub);
 228         SPLAT_TEST_FINI(sub, SPLAT_LINUX_TEST1_ID);
 229
 230         kfree(sub);
 231 }
 232
 233 int
 234 splat_linux_id(void) {
 235         return SPLAT_SUBSYSTEM_LINUX;
 236 }