On Tue, 20 Dec 2022 at 11:16, Rae Moar rmoar@google.com wrote:

Add a KUnit test for the kernel hashtable implementation in include/linux/hashtable.h.

Note that this version does not yet test each of the rcu alternative versions of functions.

Signed-off-by: Rae Moar rmoar@google.com

Thanks for completing the triangle (hash, list, hashtable) of hashtable-related tests!

This looks good to me, save for some nitpicks below. They're mostly pretty similar to Daniel's comments, so should be pretty straightforward.

Cheers, -- David

Note: The check patch script is outputting open brace errors on lines 154, 186, 231 of lib/hashtable_test.c but I believe the format of the braces on those lines is consistent with the Linux Kernel style guide. Will continue to look at these errors.

This is a problem we hit with the list test as well: because these functions have for_each in their name, checkpatch.pl assumes they're loops (using the macro), not functions.

As with the list test, we _could_ try to fix this in checkpatch, or rename the tests, but I suspect it's a special enough case (naming a function after a macro), that it's best to ignore the warnings, keeping a note like this in the patch email.

Maybe one day, checkpatch.pl will be able to tell that this is a function...

lib/Kconfig.debug | 13 ++ lib/Makefile | 1 + lib/hashtable_test.c | 299 +++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 313 insertions(+) create mode 100644 lib/hashtable_test.c

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 3fc7abffc7aa..3cf3b6f8cff4 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -2458,6 +2458,19 @@ config LIST_KUNIT_TEST

      If unsure, say N.

+config HASHTABLE_KUNIT_TEST

•   tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS
  

•   depends on KUNIT
  

•   default KUNIT_ALL_TESTS
  

•   help
  

•     This builds the hashtable KUnit test suite.
  

•     It tests the API and basic functionality of the functions
  

•     and associated macros defined in include/linux/hashtable.h.
  

•     For more information on KUnit and unit tests in general please refer
  

•     to the KUnit documentation in Documentation/dev-tools/kunit/.
  

•     If unsure, say N.
  

config LINEAR_RANGES_TEST tristate "KUnit test for linear_ranges" depends on KUNIT diff --git a/lib/Makefile b/lib/Makefile index 161d6a724ff7..9036d3aeee0a 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -370,6 +370,7 @@ obj-$(CONFIG_PLDMFW) += pldmfw/ CFLAGS_bitfield_kunit.o := $(DISABLE_STRUCTLEAK_PLUGIN) obj-$(CONFIG_BITFIELD_KUNIT) += bitfield_kunit.o obj-$(CONFIG_LIST_KUNIT_TEST) += list-test.o +obj-$(CONFIG_HASHTABLE_KUNIT_TEST) += hashtable_test.o obj-$(CONFIG_LINEAR_RANGES_TEST) += test_linear_ranges.o obj-$(CONFIG_BITS_TEST) += test_bits.o obj-$(CONFIG_CMDLINE_KUNIT_TEST) += cmdline_kunit.o diff --git a/lib/hashtable_test.c b/lib/hashtable_test.c new file mode 100644 index 000000000000..7907df66a8e7 --- /dev/null +++ b/lib/hashtable_test.c @@ -0,0 +1,299 @@ +// SPDX-License-Identifier: GPL-2.0 +/*

• • KUnit test for the Kernel Hashtable structures.
• • Copyright (C) 2022, Google LLC.
• • Author: Rae Moar rmoar@google.com
• */

+#include <kunit/test.h>

+#include <linux/hashtable.h>

+struct hashtable_test_entry {

•   int key;
  

•   int data;
  

•   struct hlist_node node;
  

•   int visited;
  

+};

+static void hashtable_test_hash_init(struct kunit *test) +{

•   /* Test the different ways of initialising a hashtable. */
  

•   DEFINE_HASHTABLE(hash1, 3);
  

•   DECLARE_HASHTABLE(hash2, 3);
  

•   hash_init(hash1);
  

•   hash_init(hash2);
  

•   KUNIT_EXPECT_TRUE(test, hash_empty(hash1));
  

•   KUNIT_EXPECT_TRUE(test, hash_empty(hash2));
  

+}

+static void hashtable_test_hash_empty(struct kunit *test) +{

•   struct hashtable_test_entry a;
  

•   DEFINE_HASHTABLE(hash, 3);
  

•   hash_init(hash);
  

•   KUNIT_EXPECT_TRUE(test, hash_empty(hash));
  

•   a.key = 1;
  

•   a.data = 13;
  

•   hash_add(hash, &a.node, a.key);
  

•   /* Hashtable should no longer be empty. */
  

•   KUNIT_EXPECT_FALSE(test, hash_empty(hash));
  

+}

+static void hashtable_test_hash_hashed(struct kunit *test) +{

•   struct hashtable_test_entry a, b;
  

•   DEFINE_HASHTABLE(hash, 3);
  

•   hash_init(hash);
  

•   a.key = 1;
  

•   a.data = 13;
  

•   b.key = 1;
  

•   b.data = 2;
  

•   hash_add(hash, &a.node, a.key);
  

•   hash_add(hash, &b.node, b.key);
  

•   KUNIT_EXPECT_TRUE(test, hash_hashed(&a.node));
  

•   KUNIT_EXPECT_TRUE(test, hash_hashed(&b.node));
  

+}

+static void hashtable_test_hash_add(struct kunit *test) +{

•   struct hashtable_test_entry a, b, *x;
  

•   int bkt;
  

•   DEFINE_HASHTABLE(hash, 3);
  

•   hash_init(hash);
  

•   a.key = 1;
  

•   a.data = 13;
  

•   a.visited = 0;
  

•   b.key = 2;
  

•   b.data = 10;
  

•   b.visited = 0;
  

•   hash_add(hash, &a.node, a.key);
  

•   hash_add(hash, &b.node, b.key);
  

•   hash_for_each(hash, bkt, x, node) {
  

•           if (x->key == a.key && x->data == a.data)
  

•                   a.visited += 1;
  

•           if (x->key == b.key && x->data == b.data)
  

•                   b.visited += 1;
  

I think we could improve this by checking 'x->key' is one of {a,b}. Daniel's suggestions below are good, otherwise perhaps something like: x->visited++; if (x->key == a.key) KUNIT_EXPECT_EQ(x->data, a.data); else if (x->key == b.key) KUNIT_EXPECT_EQ(x->data, b.data); else KUNIT_EXPECT_NEQ(x->key, x->key); /* Not an expected key. */

The other, more over-the-top option would be to have an array of struct hashtable_test_entry, rather than separate a and b variables, and to loop over them, e.g. x->visited++; for (int i = 0; i < ARRAY_SIZE(entries); ++i) { if (entires[i]->key == x->key) { … break; } KUNIT_EXPECT_NEQ_MSG(x->key, x->key, "Unexxpected element in hashtable"); }

But I suspect the first is actually cleaner.

•   }
  

•   /* Both entries should have been visited exactly once. */
  

•   KUNIT_EXPECT_EQ(test, a.visited, 1);
  

•   KUNIT_EXPECT_EQ(test, b.visited, 1);
  

+}

+static void hashtable_test_hash_del(struct kunit *test) +{

•   struct hashtable_test_entry a, b, *x;
  

•   DEFINE_HASHTABLE(hash, 3);
  

•   hash_init(hash);
  

•   a.key = 1;
  

•   a.data = 13;
  

•   b.key = 2;
  

•   b.data = 10;
  

•   b.visited = 0;
  

•   hash_add(hash, &a.node, a.key);
  

•   hash_add(hash, &b.node, b.key);
  

•   hash_del(&b.node);
  

•   hash_for_each_possible(hash, x, node, b.key) {
  

•           if (x->key == b.key && x->data == b.data)
  

•                   b.visited += 1;
  

Again, just increment x->visited here, and possibly add KUNIT_EXPECT_NEQ(x->key, b.key).

•   }
  

•   /* The deleted entry should not have been visited. */
  

•   KUNIT_EXPECT_EQ(test, b.visited, 0);
  

•   hash_del(&a.node);
  

•   /* The hashtable should be empty. */
  

•   KUNIT_EXPECT_TRUE(test, hash_empty(hash));
  

+}

+static void hashtable_test_hash_for_each(struct kunit *test) +{

•   struct hashtable_test_entry entries[3];
  

•   struct hashtable_test_entry *x;
  

•   int bkt, i, j, count;
  

•   DEFINE_HASHTABLE(hash, 3);
  

•   /* Initialize a hashtable with three entries. */
  

•   hash_init(hash);
  

•   for (i = 0; i < 3; i++) {
  

•           entries[i].key = i;
  

•           entries[i].data = i + 10;
  

•           entries[i].visited = 0;
  

•           hash_add(hash, &entries[i].node, entries[i].key);
  

•   }
  

•   count = 0;
  

•   hash_for_each(hash, bkt, x, node) {
  

•           if (x->key >= 0 && x->key < 3)
  

•                   entries[x->key].visited += 1;
  

Again, let's just increment x->visited, and maybe KUNIT_EXPECT_GEQ(x->key, 0), ..._LEQ(x->key, 3).

•           count++;
  

•   }
  

•   /* Should have visited each entry exactly once. */
  

•   KUNIT_EXPECT_EQ(test, count, 3);
  

•   for (j = 0; j < 3; j++)
  

•           KUNIT_EXPECT_EQ(test, entries[j].visited, 1);
  

+}

+static void hashtable_test_hash_for_each_safe(struct kunit *test) +{

•   struct hashtable_test_entry entries[3];
  

•   struct hashtable_test_entry *x;
  

•   struct hlist_node *tmp;
  

•   int bkt, i, j, count;
  

•   DEFINE_HASHTABLE(hash, 3);
  

•   /* Initialize a hashtable with three entries. */
  

•   hash_init(hash);
  

•   for (i = 0; i < 3; i++) {
  

•           entries[i].key = i;
  

•           entries[i].data = i + 10;
  

•           entries[i].visited = 0;
  

•           hash_add(hash, &entries[i].node, entries[i].key);
  

•   }
  

•   count = 0;
  

•   hash_for_each_safe(hash, bkt, tmp, x, node) {
  

•           if (x->key >= 0 && x->key < 3) {
  

•                   entries[x->key].visited += 1;
  

•                   hash_del(&entries[x->key].node);
  

•           }
  

•           count++;
  

•   }
  

•   /* Should have visited each entry exactly once. */
  

•   KUNIT_EXPECT_EQ(test, count, 3);
  

•   for (j = 0; j < 3; j++)
  

•           KUNIT_EXPECT_EQ(test, entries[j].visited, 1);
  

+}

+static void hashtable_test_hash_for_each_possible(struct kunit *test) +{

•   struct hashtable_test_entry entries[4];
  

•   struct hashtable_test_entry *x;
  

•   int i, j, count;
  

•   DEFINE_HASHTABLE(hash, 3);
  

•   /* Initialize a hashtable with three entries with key = 1. */
  

•   hash_init(hash);
  

•   for (i = 0; i < 3; i++) {
  

•           entries[i].key = 1;
  

•           entries[i].data = i;
  

•           entries[i].visited = 0;
  

•           hash_add(hash, &entries[i].node, entries[i].key);
  

•   }
  

•   /* Add an entry with key = 2. */
  

•   entries[3].key = 2;
  

•   entries[3].data = 3;
  

•   entries[3].visited = 0;
  

•   hash_add(hash, &entries[3].node, entries[3].key);
  

•   count = 0;
  

•   hash_for_each_possible(hash, x, node, 1) {
  

•           if (x->data >= 0 && x->data < 4)
  

•                   entries[x->data].visited += 1;
  

•           count++;
  

•   }
  

•   /* Should have visited each entry with key = 1 exactly once. */
  

•   for (j = 0; j < 3; j++)
  

•           KUNIT_EXPECT_EQ(test, entries[j].visited, 1);
  

•   /* If entry with key = 2 is in the same bucket as the entries with
  

•    * key = 1, check it was visited. Otherwise ensure that only three
  

•    * entries were visited.
  

•    */
  

•   if (hash_min(1, HASH_BITS(hash)) == hash_min(2, HASH_BITS(hash))) {
  

•           KUNIT_EXPECT_EQ(test, count, 4);
  

•           KUNIT_EXPECT_EQ(test, entries[3].visited, 1);
  

•   } else {
  

•           KUNIT_EXPECT_EQ(test, count, 3);
  

•   }
  

I'm a bit on-the-fence about whether or not this is too implementation-specific. I think the way the hashtable works here is supposed to be stable, but given that almost nothing in the actual kernel seems to rely on hash_min directly, maybe it's better to not lock it in with a test.

How about reducing this to a KUNIT_EXPECT_GEQ(test, count, 4)?

+}

+static void hashtable_test_hash_for_each_possible_safe(struct kunit *test) +{

•   struct hashtable_test_entry entries[4];
  

•   struct hashtable_test_entry *x;
  

•   struct hlist_node *tmp;
  

•   int i, j, count;
  

•   DEFINE_HASHTABLE(hash, 3);
  

•   /* Initialize a hashtable with three entries with key = 1. */
  

•   hash_init(hash);
  

•   for (i = 0; i < 3; i++) {
  

•           entries[i].key = 1;
  

•           entries[i].data = i;
  

•           entries[i].visited = 0;
  

•           hash_add(hash, &entries[i].node, entries[i].key);
  

•   }
  

•   /* Add an entry with key = 2. */
  

•   entries[3].key = 2;
  

•   entries[3].data = 3;
  

•   entries[3].visited = 0;
  

•   hash_add(hash, &entries[3].node, entries[3].key);
  

•   count = 0;
  

•   hash_for_each_possible_safe(hash, x, tmp, node, 1) {
  

•           if (x->data >= 0 && x->data < 4) {
  

•                   entries[x->data].visited += 1;
  

•                   hash_del(&entries[x->data].node);
  

•           }
  

•           count++;
  

•   }
  

•   /* Should have visited each entry with key = 1 exactly once. */
  

•   for (j = 0; j < 3; j++)
  

•           KUNIT_EXPECT_EQ(test, entries[j].visited, 1);
  

•   /* If entry with key = 2 is in the same bucket as the entries with
  

•    * key = 1, check it was visited. Otherwise ensure that only three
  

•    * entries were visited.
  

•    */
  

•   if (hash_min(1, HASH_BITS(hash)) == hash_min(2, HASH_BITS(hash))) {
  

•           KUNIT_EXPECT_EQ(test, count, 4);
  

•           KUNIT_EXPECT_EQ(test, entries[3].visited, 1);
  

•   } else {
  

•           KUNIT_EXPECT_EQ(test, count, 3);
  

•   }
  

+}

+static struct kunit_case hashtable_test_cases[] = {

•   KUNIT_CASE(hashtable_test_hash_init),
  

•   KUNIT_CASE(hashtable_test_hash_empty),
  

•   KUNIT_CASE(hashtable_test_hash_hashed),
  

•   KUNIT_CASE(hashtable_test_hash_add),
  

•   KUNIT_CASE(hashtable_test_hash_del),
  

•   KUNIT_CASE(hashtable_test_hash_for_each),
  

•   KUNIT_CASE(hashtable_test_hash_for_each_safe),
  

•   KUNIT_CASE(hashtable_test_hash_for_each_possible),
  

•   KUNIT_CASE(hashtable_test_hash_for_each_possible_safe),
  

•   {},
  

+};

+static struct kunit_suite hashtable_test_module = {

•   .name = "hashtable",
  

•   .test_cases = hashtable_test_cases,
  

+};

+kunit_test_suites(&hashtable_test_module);

+MODULE_LICENSE("GPL");

base-commit: 054be257f28ca8eeb8e3620766501b81ceb4b293

2.39.0.314.g84b9a713c41-goog