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 int
  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
  53         /*
  54          * shrinker_size can only decrease or stay the same between callbacks
  55          * in the same run, so Reset failsafe whenever shrinker increases
  56          * as this indicates a new run.
  57          */
  58         if (last_splat_linux_shrinker_size < splat_linux_shrinker_size)
  59                 failsafe = 0;
  60
  61         last_splat_linux_shrinker_size = splat_linux_shrinker_size;
  62
  63         if (sc->nr_to_scan) {
  64                 splat_linux_shrinker_size = splat_linux_shrinker_size -
  65                     MIN(sc->nr_to_scan, splat_linux_shrinker_size);
  66
  67                 splat_vprint(splat_linux_shrinker_file, SPLAT_LINUX_TEST1_NAME,
  68                     "Reclaimed %lu objects, size now %lu\n",
  69                     sc->nr_to_scan, splat_linux_shrinker_size);
  70         } else {
  71                 splat_vprint(splat_linux_shrinker_file, SPLAT_LINUX_TEST1_NAME,
  72                     "Cache size is %lu\n", splat_linux_shrinker_size);
  73         }
  74
  75         /* Far more calls than expected abort drop_slab as a failsafe */
  76         if (failsafe > 100) {
  77                 splat_vprint(splat_linux_shrinker_file, SPLAT_LINUX_TEST1_NAME,
  78                     "Far more calls than expected (%d), size now %lu\n",
  79                    failsafe, splat_linux_shrinker_size);
  80                 return -1;
  81         } else {
  82                 /*
  83                  * We only increment failsafe if it doesn't trigger.  This
  84                  * makes any failsafe failure persistent until the next test.
  85                  */
  86                 failsafe++;
  87         }
  88
  89         /* Shrinker has run, so signal back to test. */
  90         wake_up(&shrinker_wait);
  91
  92         return (int)splat_linux_shrinker_size;
  93 }
  94
  95 SPL_SHRINKER_CALLBACK_WRAPPER(splat_linux_shrinker_fn);
  96
  97 #define DROP_SLAB_CMD \
  98         "exec 0</dev/null " \
  99         "     1>/proc/sys/vm/drop_caches " \
 100         "     2>/dev/null; " \
 101         "echo 2"
 102
 103 static int
 104 splat_linux_drop_slab(struct file *file)
 105 {
 106         char *argv[] = { "/bin/sh",
 107                          "-c",
 108                          DROP_SLAB_CMD,
 109                          NULL };
 110         char *envp[] = { "HOME=/",
 111                          "TERM=linux",
 112                          "PATH=/sbin:/usr/sbin:/bin:/usr/bin",
 113                          NULL };
 114         int rc;
 115
 116         rc = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC);
 117         if (rc)
 118                 splat_vprint(file, SPLAT_LINUX_TEST1_NAME,
 119                     "Failed user helper '%s %s %s', rc = %d\n",
 120                     argv[0], argv[1], argv[2], rc);
 121
 122         return rc;
 123 }
 124
 125 /*
 126  * Verify correct shrinker functionality by registering a shrinker
 127  * with the required compatibility macros.  We then use a simulated
 128  * cache and force the systems caches to be dropped.  The shrinker
 129  * should be repeatedly called until it reports that the cache is
 130  * empty.  It is then cleanly unregistered and correct behavior is
 131  * verified.  There are now four slightly different supported shrinker
 132  * API and this test ensures the compatibility code is correct.
 133  */
 134 static int
 135 splat_linux_test1(struct file *file, void *arg)
 136 {
 137         int rc = -EINVAL;
 138
 139         /*
 140          * Globals used by the shrinker, it is not safe to run this
 141          * test concurrently this is a safe assumption for SPLAT tests.
 142          * Regardless we do some minimal checking a bail if concurrent
 143          * use is detected.
 144          */
 145         if (splat_linux_shrinker_size || splat_linux_shrinker_file) {
 146                 splat_vprint(file, SPLAT_LINUX_TEST1_NAME,
 147                     "Failed due to concurrent shrinker test, rc = %d\n", rc);
 148                 return (rc);
 149         }
 150
 151         splat_linux_shrinker_size = 1024;
 152         splat_linux_shrinker_file = file;
 153
 154         spl_register_shrinker(&splat_linux_shrinker);
 155         rc = splat_linux_drop_slab(file);
 156         if (rc)
 157                 goto out;
 158
 159         /*
 160          * By the time we get here, it is possible that the shrinker has not
 161          * yet run. splat_linux_drop_slab sends a signal for it to run, but
 162          * there is no guarantee of when it will actually run. We wait for it
 163          * to run here, terminating when either the shrinker size is now 0 or
 164          * we timeout after 1 second, which should be an eternity (error).
 165          */
 166         rc = wait_event_timeout(shrinker_wait, !splat_linux_shrinker_size, HZ);
 167         if (!rc) {
 168                 splat_vprint(file, SPLAT_LINUX_TEST1_NAME,
 169                     "Failed cache shrinking timed out, size now %lu",
 170                     splat_linux_shrinker_size);
 171                 rc = -ETIMEDOUT;
 172         } else {
 173                 rc = 0;
 174         }
 175
 176         if (!rc && splat_linux_shrinker_size != 0) {
 177                 splat_vprint(file, SPLAT_LINUX_TEST1_NAME,
 178                     "Failed cache was not shrunk to 0, size now %lu",
 179                     splat_linux_shrinker_size);
 180                 rc = -EDOM;
 181         }
 182 out:
 183         spl_unregister_shrinker(&splat_linux_shrinker);
 184
 185         splat_linux_shrinker_size = 0;
 186         splat_linux_shrinker_file = NULL;
 187
 188         return rc;
 189 }
 190
 191 splat_subsystem_t *
 192 splat_linux_init(void)
 193 {
 194         splat_subsystem_t *sub;
 195
 196         sub = kmalloc(sizeof(*sub), GFP_KERNEL);
 197         if (sub == NULL)
 198                 return NULL;
 199
 200         memset(sub, 0, sizeof(*sub));
 201         strncpy(sub->desc.name, SPLAT_LINUX_NAME, SPLAT_NAME_SIZE);
 202         strncpy(sub->desc.desc, SPLAT_LINUX_DESC, SPLAT_DESC_SIZE);
 203         INIT_LIST_HEAD(&sub->subsystem_list);
 204         INIT_LIST_HEAD(&sub->test_list);
 205         spin_lock_init(&sub->test_lock);
 206         sub->desc.id = SPLAT_SUBSYSTEM_LINUX;
 207
 208         SPLAT_TEST_INIT(sub, SPLAT_LINUX_TEST1_NAME, SPLAT_LINUX_TEST1_DESC,
 209                         SPLAT_LINUX_TEST1_ID, splat_linux_test1);
 210
 211         return sub;
 212 }
 213
 214 void
 215 splat_linux_fini(splat_subsystem_t *sub)
 216 {
 217         ASSERT(sub);
 218         SPLAT_TEST_FINI(sub, SPLAT_LINUX_TEST1_ID);
 219
 220         kfree(sub);
 221 }
 222
 223 int
 224 splat_linux_id(void) {
 225         return SPLAT_SUBSYSTEM_LINUX;
 226 }