Re: [PATCH v3 1/7] kunit: Replace fixed-size log with dynamically-extending buffer

Rae Moar
2023-08-09T21:10:29Z

On Wed, Aug 9, 2023 at 11:54 AM Richard Fitzgerald
<rf@opensource.cirrus.com> wrote:
>
> 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. If the test fails the new function
> get_concatenated_log() constructs a single contiguous string from the
> log fragments so that the whole log can be emitted in the failure
> message.

Hello!

All the tests now pass for me and this patch now looks good to me. I
have tested it and it seems to be working well.

I just have a few nits below. But I am overall happy with this patch.

Reviewed-by: Rae Moar <rmoar@google.com>

-Rae

>
> Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
> ---
> include/kunit/test.h | 25 +++++++++++-----
> lib/kunit/debugfs.c | 65 ++++++++++++++++++++++++++++++++++--------
> lib/kunit/kunit-test.c | 48 +++++++++++++++++++++++++------
> lib/kunit/test.c | 63 ++++++++++++++++++++++++++++------------
> 4 files changed, 155 insertions(+), 46 deletions(-)
>
> diff --git a/include/kunit/test.h b/include/kunit/test.h
> index d33114097d0d..cb5082efc91c 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 +85,17 @@ struct kunit_attributes {
> enum kunit_speed speed;
> };
>
> +struct kunit_log_frag {
> + struct list_head list;
> + char buf[KUNIT_LOG_FRAGMENT_SIZE];
> +};
> +
> +static inline void kunit_init_log_frag(struct kunit_log_frag *frag)
> +{
> + INIT_LIST_HEAD(&frag->list);
> + frag->buf[0] = '\0';
> +}
> +
> /**
> * struct kunit_case - represents an individual test case.
> *
> @@ -132,7 +143,7 @@ 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 +263,7 @@ 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;
> };
>
> @@ -278,7 +289,7 @@ 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 */

To respond to some of the comments from the previous version, I am
fine with the list_head being a pointer considering there can only be
one list_head in this struct definition.

> struct kunit_try_catch try_catch;
> /* param_value is the current parameter value for a test case. */
> const void *param_value;
> @@ -314,7 +325,7 @@ const char *kunit_filter_glob(void);
> char *kunit_filter(void);
> char *kunit_filter_action(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);
>
> @@ -472,7 +483,7 @@ 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..a199f83bac67 100644
> --- a/lib/kunit/kunit-test.c
> +++ b/lib/kunit/kunit-test.c
> @@ -530,12 +530,37 @@ static struct kunit_suite kunit_resource_test_suite = {
> .test_cases = kunit_resource_test_cases,
> };
>
> +static char *get_concatenated_log(struct kunit *test, const struct list_head *log)
> +{
> + struct kunit_log_frag *frag;
> + size_t len = 0;
> + char *p;

I wonder if we could change the name of p to be a bit more
descriptive. Maybe concat_log?

> +
> + list_for_each_entry(frag, log, list)
> + len += strlen(frag->buf);
> +
> + len++; /* for terminating '\0' */
> + p = kunit_kzalloc(test, len, GFP_KERNEL);
> +
> + list_for_each_entry(frag, log, list)
> + strlcat(p, frag->buf, len);
> +
> + return p;
> +}
> +
> 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);

This section of the test is pretty dense. I would love to see at least
one comment in this section. Maybe it could be here and say something
like:
"/* Allocate, initialize, and then add the first fragment of 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 +568,17 @@ 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);

This test passes when CONFIG_KUNIT_DEBUGFS=n while most of the other
tests are skipped. Should this test be skipped instead?

I'm assuming since the assert/expect statements at the beginning are
run even if CONFIG_KUNIT_DEBUGFS=n, this test should not be skipped
but I just wanted to check.

> #endif
> @@ -558,11 +586,15 @@ 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) {

This is a small nit but I would prefer that the if statements to
decide whether CONFIG_KUNIT_DEBUGFS is enabled were uniform. So I
would prefer that we choose between if (test->log) and #ifdef
CONFIG_KUNIT_DEBUGFS. I think we originally chose to use if
(test->log) here to avoid the compile-time #ifdef.

> - 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",
> + get_concatenated_log(test, test->log));
> + 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 49698a168437..dfe51bc2b387 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)

I would love to see just a short comment describing kunit_log_extend
to prevent confusion with kunit_log_append.

> +{
> + 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
>