[PATCH v2 1/6] kunit: Replace fixed-size log with dynamically-extending buffer

From: Richard Fitzgerald
Date: Tue Aug 08 2023 - 12:13:57 EST

Re-implement the log buffer as a list of buffer fragments that can
be extended as the size of the log info grows.

When using parameterization the test case can run many times and create
a large amount of log. It's not really practical to keep increasing the
size of the fixed buffer every time a test needs more space. And a big
fixed buffer wastes memory.

The original char *log pointer is replaced by a pointer to a list of
struct kunit_log_frag, each containing a fixed-size buffer.

kunit_log_append() now attempts to append to the last kunit_log_frag in
the list. If there isn't enough space it will append a new kunit_log_frag
to the list. This simple implementation does not attempt to completely
fill the buffer in every kunit_log_frag.

The 'log' member of kunit_suite, kunit_test_case and kunit_suite must be a
pointer because the API of kunit_log() requires that is the same type in
all three structs. As kunit.log is a pointer to the 'log' of the current
kunit_case, it must be a pointer in the other two structs.

The existing kunit-test.c log tests have been updated to build against the
new fragmented log implementation.

Signed-off-by: Richard Fitzgerald <rf@xxxxxxxxxxxxxxxxxxxxx>
---
include/kunit/test.h | 25 +++++++++++-----
lib/kunit/debugfs.c | 65 ++++++++++++++++++++++++++++++++++--------
lib/kunit/kunit-test.c | 29 +++++++++++++------
lib/kunit/test.c | 63 ++++++++++++++++++++++++++++------------
4 files changed, 136 insertions(+), 46 deletions(-)

diff --git a/include/kunit/test.h b/include/kunit/test.h
index 011e0d6bb506..ef8e09aafe1b 100644
--- a/include/kunit/test.h
+++ b/include/kunit/test.h
@@ -33,8 +33,8 @@ DECLARE_STATIC_KEY_FALSE(kunit_running);

struct kunit;

-/* Size of log associated with test. */
-#define KUNIT_LOG_SIZE 2048
+/* Size of log buffer fragments. */
+#define KUNIT_LOG_FRAGMENT_SIZE (256 - sizeof(struct list_head))

/* Maximum size of parameter description string. */
#define KUNIT_PARAM_DESC_SIZE 128
@@ -85,6 +85,11 @@ struct kunit_attributes {
enum kunit_speed speed;
};

+struct kunit_log_frag {
+ struct list_head list;
+ char buf[KUNIT_LOG_FRAGMENT_SIZE];
+};
+
/**
* struct kunit_case - represents an individual test case.
*
@@ -132,7 +137,7 @@ struct kunit_case {
/* private: internal use only. */
enum kunit_status status;
char *module_name;
- char *log;
+ struct list_head *log;
};

static inline char *kunit_status_to_ok_not_ok(enum kunit_status status)
@@ -252,7 +257,7 @@ struct kunit_suite {
/* private: internal use only */
char status_comment[KUNIT_STATUS_COMMENT_SIZE];
struct dentry *debugfs;
- char *log;
+ struct list_head *log;
int suite_init_err;
};

@@ -272,7 +277,7 @@ struct kunit {

/* private: internal use only. */
const char *name; /* Read only after initialization! */
- char *log; /* Points at case log after initialization */
+ struct list_head *log; /* Points at case log after initialization */
struct kunit_try_catch try_catch;
/* param_value is the current parameter value for a test case. */
const void *param_value;
@@ -304,7 +309,7 @@ static inline void kunit_set_failure(struct kunit *test)

bool kunit_enabled(void);

-void kunit_init_test(struct kunit *test, const char *name, char *log);
+void kunit_init_test(struct kunit *test, const char *name, struct list_head *log);

int kunit_run_tests(struct kunit_suite *suite);

@@ -317,6 +322,12 @@ int __kunit_test_suites_init(struct kunit_suite * const * const suites, int num_

void __kunit_test_suites_exit(struct kunit_suite **suites, int num_suites);

+static inline void kunit_init_log_frag(struct kunit_log_frag *frag)
+{
+ INIT_LIST_HEAD(&frag->list);
+ frag->buf[0] = '\0';
+}
+
#if IS_BUILTIN(CONFIG_KUNIT)
int kunit_run_all_tests(void);
#else
@@ -451,7 +462,7 @@ static inline void *kunit_kcalloc(struct kunit *test, size_t n, size_t size, gfp

void kunit_cleanup(struct kunit *test);

-void __printf(2, 3) kunit_log_append(char *log, const char *fmt, ...);
+void __printf(2, 3) kunit_log_append(struct list_head *log, const char *fmt, ...);

/**
* kunit_mark_skipped() - Marks @test_or_suite as skipped
diff --git a/lib/kunit/debugfs.c b/lib/kunit/debugfs.c
index 22c5c496a68f..a26b6d31bd2f 100644
--- a/lib/kunit/debugfs.c
+++ b/lib/kunit/debugfs.c
@@ -5,6 +5,7 @@
*/

#include <linux/debugfs.h>
+#include <linux/list.h>
#include <linux/module.h>

#include <kunit/test.h>
@@ -37,14 +38,15 @@ void kunit_debugfs_init(void)
debugfs_rootdir = debugfs_create_dir(KUNIT_DEBUGFS_ROOT, NULL);
}

-static void debugfs_print_result(struct seq_file *seq,
- struct kunit_suite *suite,
- struct kunit_case *test_case)
+static void debugfs_print_log(struct seq_file *seq, const struct list_head *log)
{
- if (!test_case || !test_case->log)
+ struct kunit_log_frag *frag;
+
+ if (!log)
return;

- seq_printf(seq, "%s", test_case->log);
+ list_for_each_entry(frag, log, list)
+ seq_puts(seq, frag->buf);
}

/*
@@ -69,10 +71,9 @@ static int debugfs_print_results(struct seq_file *seq, void *v)
seq_printf(seq, KUNIT_SUBTEST_INDENT "1..%zd\n", kunit_suite_num_test_cases(suite));

kunit_suite_for_each_test_case(suite, test_case)
- debugfs_print_result(seq, suite, test_case);
+ debugfs_print_log(seq, test_case->log);

- if (suite->log)
- seq_printf(seq, "%s", suite->log);
+ debugfs_print_log(seq, suite->log);

seq_printf(seq, "%s %d %s\n",
kunit_status_to_ok_not_ok(success), 1, suite->name);
@@ -100,14 +101,53 @@ static const struct file_operations debugfs_results_fops = {
.release = debugfs_release,
};

+static struct list_head *kunit_debugfs_alloc_log(void)
+{
+ struct list_head *log;
+ struct kunit_log_frag *frag;
+
+ log = kzalloc(sizeof(*log), GFP_KERNEL);
+ if (!log)
+ return NULL;
+
+ INIT_LIST_HEAD(log);
+
+ frag = kmalloc(sizeof(*frag), GFP_KERNEL);
+ if (!frag) {
+ kfree(log);
+ return NULL;
+ }
+
+ kunit_init_log_frag(frag);
+ list_add_tail(&frag->list, log);
+
+ return log;
+}
+
+static void kunit_debugfs_free_log(struct list_head *log)
+{
+ struct kunit_log_frag *frag, *n;
+
+ if (!log)
+ return;
+
+ list_for_each_entry_safe(frag, n, log, list) {
+ list_del(&frag->list);
+ kfree(frag);
+ }
+
+ kfree(log);
+}
+
void kunit_debugfs_create_suite(struct kunit_suite *suite)
{
struct kunit_case *test_case;

/* Allocate logs before creating debugfs representation. */
- suite->log = kzalloc(KUNIT_LOG_SIZE, GFP_KERNEL);
+ suite->log = kunit_debugfs_alloc_log();
+
kunit_suite_for_each_test_case(suite, test_case)
- test_case->log = kzalloc(KUNIT_LOG_SIZE, GFP_KERNEL);
+ test_case->log = kunit_debugfs_alloc_log();

suite->debugfs = debugfs_create_dir(suite->name, debugfs_rootdir);

@@ -121,7 +161,8 @@ void kunit_debugfs_destroy_suite(struct kunit_suite *suite)
struct kunit_case *test_case;

debugfs_remove_recursive(suite->debugfs);
- kfree(suite->log);
+ kunit_debugfs_free_log(suite->log);
+
kunit_suite_for_each_test_case(suite, test_case)
- kfree(test_case->log);
+ kunit_debugfs_free_log(test_case->log);
}
diff --git a/lib/kunit/kunit-test.c b/lib/kunit/kunit-test.c
index 83d8e90ca7a2..54dc011c8980 100644
--- a/lib/kunit/kunit-test.c
+++ b/lib/kunit/kunit-test.c
@@ -533,9 +533,16 @@ static struct kunit_suite kunit_resource_test_suite = {
static void kunit_log_test(struct kunit *test)
{
struct kunit_suite suite;
+ struct kunit_log_frag *frag;

- suite.log = kunit_kzalloc(test, KUNIT_LOG_SIZE, GFP_KERNEL);
+ suite.log = kunit_kzalloc(test, sizeof(*suite.log), GFP_KERNEL);
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, suite.log);
+ INIT_LIST_HEAD(suite.log);
+ frag = kunit_kmalloc(test, sizeof(*frag), GFP_KERNEL);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, frag);
+ kunit_init_log_frag(frag);
+ KUNIT_EXPECT_EQ(test, frag->buf[0], '\0');
+ list_add_tail(&frag->list, suite.log);

kunit_log(KERN_INFO, test, "put this in log.");
kunit_log(KERN_INFO, test, "this too.");
@@ -543,14 +550,17 @@ static void kunit_log_test(struct kunit *test)
kunit_log(KERN_INFO, &suite, "along with this.");

#ifdef CONFIG_KUNIT_DEBUGFS
+ frag = list_first_entry(test->log, struct kunit_log_frag, list);
KUNIT_EXPECT_NOT_ERR_OR_NULL(test,
- strstr(test->log, "put this in log."));
+ strstr(frag->buf, "put this in log."));
KUNIT_EXPECT_NOT_ERR_OR_NULL(test,
- strstr(test->log, "this too."));
+ strstr(frag->buf, "this too."));
+
+ frag = list_first_entry(suite.log, struct kunit_log_frag, list);
KUNIT_EXPECT_NOT_ERR_OR_NULL(test,
- strstr(suite.log, "add to suite log."));
+ strstr(frag->buf, "add to suite log."));
KUNIT_EXPECT_NOT_ERR_OR_NULL(test,
- strstr(suite.log, "along with this."));
+ strstr(frag->buf, "along with this."));
#else
KUNIT_EXPECT_NULL(test, test->log);
#endif
@@ -558,11 +568,14 @@ static void kunit_log_test(struct kunit *test)

static void kunit_log_newline_test(struct kunit *test)
{
+ struct kunit_log_frag *frag;
+
kunit_info(test, "Add newline\n");
if (test->log) {
- KUNIT_ASSERT_NOT_NULL_MSG(test, strstr(test->log, "Add newline\n"),
- "Missing log line, full log:\n%s", test->log);
- KUNIT_EXPECT_NULL(test, strstr(test->log, "Add newline\n\n"));
+ frag = list_first_entry(test->log, struct kunit_log_frag, list);
+ KUNIT_ASSERT_NOT_NULL_MSG(test, strstr(frag->buf, "Add newline\n"),
+ "Missing log line, full log:\n%s", frag->buf);
+ KUNIT_EXPECT_NULL(test, strstr(frag->buf, "Add newline\n\n"));
} else {
kunit_skip(test, "only useful when debugfs is enabled");
}
diff --git a/lib/kunit/test.c b/lib/kunit/test.c
index cb9797fa6303..bdb361741214 100644
--- a/lib/kunit/test.c
+++ b/lib/kunit/test.c
@@ -11,6 +11,7 @@
#include <kunit/test-bug.h>
#include <kunit/attributes.h>
#include <linux/kernel.h>
+#include <linux/list.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/panic.h>
@@ -114,46 +115,66 @@ static void kunit_print_test_stats(struct kunit *test,
* already present.
* @log: The log to add the newline to.
*/
-static void kunit_log_newline(char *log)
+static void kunit_log_newline(struct kunit_log_frag *frag)
{
int log_len, len_left;

- log_len = strlen(log);
- len_left = KUNIT_LOG_SIZE - log_len - 1;
+ log_len = strlen(frag->buf);
+ len_left = sizeof(frag->buf) - log_len - 1;

- if (log_len > 0 && log[log_len - 1] != '\n')
- strncat(log, "\n", len_left);
+ if (log_len > 0 && frag->buf[log_len - 1] != '\n')
+ strncat(frag->buf, "\n", len_left);
}

-/*
- * Append formatted message to log, size of which is limited to
- * KUNIT_LOG_SIZE bytes (including null terminating byte).
- */
-void kunit_log_append(char *log, const char *fmt, ...)
+static struct kunit_log_frag *kunit_log_extend(struct list_head *log)
+{
+ struct kunit_log_frag *frag;
+
+ frag = kmalloc(sizeof(*frag), GFP_KERNEL);
+ if (!frag)
+ return NULL;
+
+ kunit_init_log_frag(frag);
+ list_add_tail(&frag->list, log);
+
+ return frag;
+}
+
+/* Append formatted message to log, extending the log buffer if necessary. */
+void kunit_log_append(struct list_head *log, const char *fmt, ...)
{
va_list args;
+ struct kunit_log_frag *frag;
int len, log_len, len_left;

if (!log)
return;

- log_len = strlen(log);
- len_left = KUNIT_LOG_SIZE - log_len - 1;
- if (len_left <= 0)
- return;
+ frag = list_last_entry(log, struct kunit_log_frag, list);
+ log_len = strlen(frag->buf);
+ len_left = sizeof(frag->buf) - log_len - 1;

/* Evaluate length of line to add to log */
va_start(args, fmt);
len = vsnprintf(NULL, 0, fmt, args) + 1;
va_end(args);

+ if (len > len_left) {
+ frag = kunit_log_extend(log);
+ if (!frag)
+ return;
+
+ len_left = sizeof(frag->buf) - 1;
+ log_len = 0;
+ }
+
/* Print formatted line to the log */
va_start(args, fmt);
- vsnprintf(log + log_len, min(len, len_left), fmt, args);
+ vsnprintf(frag->buf + log_len, min(len, len_left), fmt, args);
va_end(args);

/* Add newline to end of log if not already present. */
- kunit_log_newline(log);
+ kunit_log_newline(frag);
}
EXPORT_SYMBOL_GPL(kunit_log_append);

@@ -359,14 +380,18 @@ void __kunit_do_failed_assertion(struct kunit *test,
}
EXPORT_SYMBOL_GPL(__kunit_do_failed_assertion);

-void kunit_init_test(struct kunit *test, const char *name, char *log)
+void kunit_init_test(struct kunit *test, const char *name, struct list_head *log)
{
spin_lock_init(&test->lock);
INIT_LIST_HEAD(&test->resources);
test->name = name;
test->log = log;
- if (test->log)
- test->log[0] = '\0';
+ if (test->log) {
+ struct kunit_log_frag *frag = list_first_entry(test->log,
+ struct kunit_log_frag,
+ list);
+ frag->buf[0] = '\0';
+ }
test->status = KUNIT_SUCCESS;
test->status_comment[0] = '\0';
}
--
2.30.2