The kunit_remove_resource() function is used to unlink a resource from
the list of resources in the test, making it no longer show up in
kunit_find_resource().
However, this could lead to a race condition if two threads called
kunit_remove_resource() on the same resource at the same time: the
resource would be removed from the list twice (causing a crash at the
second list_del()), and the refcount for the resource would be
decremented twice (instead of once, for the reference held by the
resource list).
Fix both problems, the first by using list_del_init(), and the second by
checking if the resource has already been removed using list_empty(),
and only decrementing its refcount if it has not.
Also add a KUnit test for the kunit_remove_resource() function which
tests this behaviour.
Reported-by: Daniel Latypov <dlatypov(a)google.com>
Signed-off-by: David Gow <davidgow(a)google.com>
Reviewed-by: Brendan Higgins <brendanhiggins(a)google.com>
---
Changes since v1:
https://lore.kernel.org/linux-kselftest/20220318064959.3298768-1-davidgow@g…
- Rebased on top of Daniel's split of the resource system into
resource.{c,h}
- https://lore.kernel.org/linux-kselftest/20220328174143.857262-1-dlatypov@go…
- https://lore.kernel.org/linux-kselftest/20220328174143.857262-2-dlatypov@go…
lib/kunit/kunit-test.c | 35 +++++++++++++++++++++++++++++++++++
lib/kunit/resource.c | 8 ++++++--
2 files changed, 41 insertions(+), 2 deletions(-)
diff --git a/lib/kunit/kunit-test.c b/lib/kunit/kunit-test.c
index 555601d17f79..9005034558aa 100644
--- a/lib/kunit/kunit-test.c
+++ b/lib/kunit/kunit-test.c
@@ -190,6 +190,40 @@ static void kunit_resource_test_destroy_resource(struct kunit *test)
KUNIT_EXPECT_TRUE(test, list_empty(&ctx->test.resources));
}
+static void kunit_resource_test_remove_resource(struct kunit *test)
+{
+ struct kunit_test_resource_context *ctx = test->priv;
+ struct kunit_resource *res = kunit_alloc_and_get_resource(
+ &ctx->test,
+ fake_resource_init,
+ fake_resource_free,
+ GFP_KERNEL,
+ ctx);
+
+ /* The resource is in the list */
+ KUNIT_EXPECT_FALSE(test, list_empty(&ctx->test.resources));
+
+ /* Remove the resource. The pointer is still valid, but it can't be
+ * found.
+ */
+ kunit_remove_resource(test, res);
+ KUNIT_EXPECT_TRUE(test, list_empty(&ctx->test.resources));
+ /* We haven't been freed yet. */
+ KUNIT_EXPECT_TRUE(test, ctx->is_resource_initialized);
+
+ /* Removing the resource multiple times is valid. */
+ kunit_remove_resource(test, res);
+ KUNIT_EXPECT_TRUE(test, list_empty(&ctx->test.resources));
+ /* Despite having been removed twice (from only one reference), the
+ * resource still has not been freed.
+ */
+ KUNIT_EXPECT_TRUE(test, ctx->is_resource_initialized);
+
+ /* Free the resource. */
+ kunit_put_resource(res);
+ KUNIT_EXPECT_FALSE(test, ctx->is_resource_initialized);
+}
+
static void kunit_resource_test_cleanup_resources(struct kunit *test)
{
int i;
@@ -387,6 +421,7 @@ static struct kunit_case kunit_resource_test_cases[] = {
KUNIT_CASE(kunit_resource_test_init_resources),
KUNIT_CASE(kunit_resource_test_alloc_resource),
KUNIT_CASE(kunit_resource_test_destroy_resource),
+ KUNIT_CASE(kunit_resource_test_remove_resource),
KUNIT_CASE(kunit_resource_test_cleanup_resources),
KUNIT_CASE(kunit_resource_test_proper_free_ordering),
KUNIT_CASE(kunit_resource_test_static),
diff --git a/lib/kunit/resource.c b/lib/kunit/resource.c
index b8bced246217..09ec392d2323 100644
--- a/lib/kunit/resource.c
+++ b/lib/kunit/resource.c
@@ -98,11 +98,15 @@ EXPORT_SYMBOL_GPL(kunit_alloc_and_get_resource);
void kunit_remove_resource(struct kunit *test, struct kunit_resource *res)
{
unsigned long flags;
+ bool was_linked;
spin_lock_irqsave(&test->lock, flags);
- list_del(&res->node);
+ was_linked = !list_empty(&res->node);
+ list_del_init(&res->node);
spin_unlock_irqrestore(&test->lock, flags);
- kunit_put_resource(res);
+
+ if (was_linked)
+ kunit_put_resource(res);
}
EXPORT_SYMBOL_GPL(kunit_remove_resource);
--
2.35.1.1094.g7c7d902a7c-goog
Currently if opening /dev/null fails to open then file pointer fp
is null and further access to fp via fprintf will cause a null
pointer dereference. Fix this by returning a negative error value
when a null fp is detected.
Detected using cppcheck static analysis:
tools/testing/selftests/resctrl/fill_buf.c:124:6: note: Assuming
that condition '!fp' is not redundant
if (!fp)
^
tools/testing/selftests/resctrl/fill_buf.c:126:10: note: Null
pointer dereference
fprintf(fp, "Sum: %d ", ret);
Fixes: a2561b12fe39 ("selftests/resctrl: Add built in benchmark")
Signed-off-by: Colin Ian King <colin.i.king(a)gmail.com>
---
V2: Add cppcheck analysis information
---
tools/testing/selftests/resctrl/fill_buf.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/resctrl/fill_buf.c b/tools/testing/selftests/resctrl/fill_buf.c
index 51e5cf22632f..56ccbeae0638 100644
--- a/tools/testing/selftests/resctrl/fill_buf.c
+++ b/tools/testing/selftests/resctrl/fill_buf.c
@@ -121,8 +121,10 @@ static int fill_cache_read(unsigned char *start_ptr, unsigned char *end_ptr,
/* Consume read result so that reading memory is not optimized out. */
fp = fopen("/dev/null", "w");
- if (!fp)
+ if (!fp) {
perror("Unable to write to /dev/null");
+ return -1;
+ }
fprintf(fp, "Sum: %d ", ret);
fclose(fp);
--
2.35.1
Hello,
The aim of this series is to print a message to let users know a possible
cause of failure, if the result of MBM&CMT tests is failed on Intel CPU.
In order to detect Intel vendor, I extended AMD vendor detect function.
Difference from v4:
- Fixed the typos.
- Changed "get_vendor() != ARCH_AMD" to "get_vendor() == ARCH_INTEL".
- Reorder the declarations based on line length from longest to shortest.
https://lore.kernel.org/lkml/20220316055940.292550-1-tan.shaopeng@jp.fujits… [PATCH v4]
This patch series is based on v5.17.
Shaopeng Tan (2):
selftests/resctrl: Extend CPU vendor detection
selftests/resctrl: Print a message if the result of MBM&CMT tests is
failed on Intel CPU
tools/testing/selftests/resctrl/cat_test.c | 2 +-
tools/testing/selftests/resctrl/resctrl.h | 5 ++-
.../testing/selftests/resctrl/resctrl_tests.c | 45 +++++++++++++------
tools/testing/selftests/resctrl/resctrlfs.c | 2 +-
4 files changed, 37 insertions(+), 17 deletions(-)
--
2.27.0