Re: [igt-dev] [PATCH i-g-t v2 3/4] lib/igt_kmod: add compatibility for KUnit

[Isabella Basso]

Hi, Janusz,

> Am 09/09/2022 um 12:18 PM schrieb Janusz Krzysztofik <janusz.krzysztofik@xxxxxxxxxxxxxxx>:
> 
> Hi Isabella,
> 
> On Monday, 29 August 2022 02:09:19 CEST Isabella Basso wrote:
>> This adds functions for both executing the tests as well as parsing (K)TAP
>> kmsg output, as per the KTAP spec [1].
>> 
>> [1] https://www.kernel.org/doc/html/latest/dev-tools/ktap.html
>> 
>> Signed-off-by: Isabella Basso <isabbasso@xxxxxxxxxx>
>> ---
>> lib/igt_kmod.c | 290 +++++++++++++++++++++++++++++++++++++++++++++++++
>> lib/igt_kmod.h |   2 +
>> 2 files changed, 292 insertions(+)
>> 
>> diff --git a/lib/igt_kmod.c b/lib/igt_kmod.c
>> index 97cac7f5..93cdfcc5 100644
>> --- a/lib/igt_kmod.c
>> +++ b/lib/igt_kmod.c
>> @@ -25,6 +25,7 @@
>> #include <signal.h>
>> #include <errno.h>
>> #include <sys/utsname.h>
>> +#include <limits.h>
>> 
>> #include "igt_aux.h"
>> #include "igt_core.h"
>> @@ -32,6 +33,8 @@
>> #include "igt_sysfs.h"
>> #include "igt_taints.h"
>> 
>> +#define BUF_LEN 4096
>> +
>> /**
>>  * SECTION:igt_kmod
>>  * @short_description: Wrappers around libkmod for module loading/unloading
>> @@ -713,6 +716,293 @@ void igt_kselftest_get_tests(struct kmod_module *kmod,
>> 	kmod_module_info_free_list(pre);
>> }
>> 
>> +/**
>> + * lookup_value:
>> + * @haystack: the string to search in
>> + * @needle: the string to search for
>> + *
>> + * Returns: the value of the needle in the haystack, or -1 if not found.
>> + */
>> +static long lookup_value(const char *haystack, const char *needle)
>> +{
>> +	const char *needle_rptr;
>> +	char *needle_end;
>> +	long num;
>> +
>> +	needle_rptr = strcasestr(haystack, needle);
>> +
>> +	if (needle_rptr == NULL)
>> +		return -1;
>> +
>> +	/* skip search string and whitespaces after it */
>> +	needle_rptr += strlen(needle);
>> +
>> +	num = strtol(needle_rptr, &needle_end, 10);
>> +
>> +	if (needle_rptr == needle_end)
>> +		return -1;
>> +
>> +	if (num == LONG_MIN || num == LONG_MAX)
>> +		return 0;
>> +
>> +	return num > 0 ? num : 0;
>> +}
>> +
>> +static int find_next_tap_subtest(char *record, char *test_name,
>> +				 bool is_subtest)
>> +{
>> +	const char *name_lookup_str,
>> +	      *lend, *version_rptr, *name_rptr;
>> +	long test_count;
>> +
>> +	name_lookup_str = "test: ";
>> +
>> +	version_rptr = strcasestr(record, "TAP version ");
>> +	name_rptr = strcasestr(record, name_lookup_str);
>> +
>> +	/*
>> +	 * total test count will almost always appear as 0..N at the beginning
>> +	 * of a run, so we use it as indication of a run
>> +	 */
>> +	test_count = lookup_value(record, "..");
>> +
>> +	/* no count found, so this is probably not starting a (sub)test */
>> +	if (test_count < 0) {
>> +		if (name_rptr != NULL) {
>> +			if (test_name[0] == '\0')
>> +				strncpy(test_name,
>> +					name_rptr + strlen(name_lookup_str),
>> +					BUF_LEN);
>> +			else if (strcmp(test_name, name_rptr + strlen(name_lookup_str)) == 0)
>> +				return 0;
>> +			else
>> +				test_name[0] = '\0';
>> +
>> +		}
>> +		return -1;
>> +	}
>> +
>> +	/*
>> +	 * "(K)TAP version XX" should be the first line on all (sub)tests as per
>> +	 * https://www.kernel.org/doc/html/latest/dev-tools/ktap.html#version-lines
>> +	 * but actually isn't, as it currently depends on whoever writes the
>> +	 * test to print this info
>> +	 */
>> +	if (version_rptr == NULL)
>> +		igt_info("Missing test version string\n");
>> +
>> +	if (name_rptr == NULL) {
>> +		/* we have to keep track of the name string, as it might be
>> +		 * contained in a line read previously */
>> +		if (test_name[0] == '\0') {
>> +			igt_info("Missing test name string\n");
>> +
>> +			if (is_subtest)
>> +				igt_info("Running %ld subtests...\n", test_count);
>> +			else
>> +				igt_info("Running %ld tests...\n", test_count);
>> +		} else {
>> +			lend = strchrnul(test_name, '\n');
>> +
>> +			if (*lend == '\0') {
>> +				if (is_subtest)
>> +					igt_info("Executing %ld subtests in: %s\n",
>> +						 test_count, test_name);
>> +				else
>> +					igt_info("Executing %ld tests in: %s\n",
>> +						 test_count, test_name);
>> +				return test_count;
>> +			}
>> +
>> +			if (is_subtest)
>> +				igt_info("Executing %ld subtests in: %.*s\n",
>> +					 test_count, (int)(lend - test_name),
>> +					 test_name);
>> +			else
>> +				igt_info("Executing %ld tests in: %.*s\n",
>> +					 test_count, (int)(lend - test_name),
>> +					 test_name);
>> +			test_name[0] = '\0';
>> +		}
>> +	} else {
>> +		name_rptr += strlen(name_lookup_str);
>> +		lend = strchrnul(name_rptr, '\n');
>> +		/*
>> +		 * as the test count comes after the test name we need not check
>> +		 * for a long line again
>> +		 */
>> +		if (is_subtest)
>> +			igt_info("Executing %ld subtests in: %.*s\n",
>> +				 test_count, (int)(lend - name_rptr),
>> +				 name_rptr);
>> +		else
>> +			igt_info("Executing %ld tests in: %.*s\n",
>> +				 test_count, (int)(lend - name_rptr),
>> +				 name_rptr);
>> +	}
>> +
>> +	return test_count;
>> +}
>> +
>> +static void parse_kmsg_for_tap(const char *lstart, char *lend,
>> +			       int *sublevel, bool *failed_tests)
>> +{
>> +	const char *nok_rptr, *comment_start, *value_parse_start;
>> +
>> +	nok_rptr = strstr(lstart, "not ok ");
>> +	if (nok_rptr != NULL) {
>> +		igt_warn("kmsg> %.*s\n",
>> +			 (int)(lend - lstart), lstart);
>> +		*failed_tests = true;
>> +		return;
>> +	}
>> +
>> +	comment_start = strchrnul(lstart, '#');
>> +
>> +	/* check if we're still in a subtest */
>> +	if (*comment_start != '\0') {
>> +		comment_start++;
>> +		value_parse_start = comment_start;
>> +
>> +		if (lookup_value(value_parse_start, "fail: ") > 0) {
>> +			igt_warn("kmsg> %.*s\n",
>> +				 (int)(lend - comment_start), comment_start);
>> +			*failed_tests = true;
>> +			(*sublevel)--;
>> +			return;
>> +		}
>> +	}
>> +
>> +	igt_info("kmsg> %.*s\n",
>> +		 (int)(lend - lstart), lstart);
>> +}
>> +
>> +static void igt_kunit_subtests(int fd, char *record,
>> +			       int *sublevel, bool *failed_tests)
> 
> This function looks like nothing but a KTAP parser.  It doesn't perform any 
> operations required for execution of kunit tests.  Shouldn't we better name it 
> like igt_ktap_parser or something like that?  Besides, I would move that 
> parser code to a separate source file.
> 
>> +{
>> +	char test_name[BUF_LEN + 1], *lend;
>> +
>> +	lend = NULL;
>> +	test_name[0] = '\0';
>> +	test_name[BUF_LEN] = '\0';
>> +
>> +	while (*sublevel >= 0) {
>> +		const char *lstart;
>> +		ssize_t r;
>> +
>> +		if (lend != NULL && *lend != '\0')
>> +			lseek(fd, (int) (lend - record), SEEK_CUR);
>> +
>> +		r = read(fd, record, BUF_LEN);
>> +
>> +		if (r <= 0) {
>> +			switch (errno) {
>> +			case EINTR:
>> +				continue;
>> +			case EPIPE:
>> +				igt_warn("kmsg truncated: too many messages. \
>> +					 You may want to increase log_buf_len \
>> +					 in your boot options\n");
>> +				continue;
>> +			case !EAGAIN:
>> +				igt_warn("kmsg truncated: unknown error (%m)\n");something 
> 
> If the intention here is to display this warning only in other cases but 
> EAGAIN error then that won't work as intended.
> 
>> +				*sublevel = -1;
> 
> Shouldn't *sublevel be also set to -1 in all cases but EINTR and EPIPE, 
> whether EAGAIN or anything else?
> 
> Other than that, please use /* fallthrough */ marking if you intentionally 
> omit break;
> 
>> +			default:
>> +				break;
>> +			}
>> +			break;
>> +		}
>> +
>> +		lend = strchrnul(record, '\n');
>> +
>> +		/* in case line > 4096 */
>> +		if (*lend == '\0')
>> +			continue;
> 
> That means we are free to ignore initial fragments of lines exceeding 4096 
> characters, but still will be looking at trailing fragments of those lines.  
> This approach seems sub-optimal to me.  Wouldn't it be more convenient if we 
> used line buffered I/O instead of read()?
> 
>> +
>> +		if (find_next_tap_subtest(record, test_name, *sublevel > 0) != -1)
>> +			(*sublevel)++;
>> +
>> +		if (*sublevel > 0) {
>> +			lstart = strchrnul(record, ';');
>> +
>> +			if (*lstart == '\0') {
>> +				igt_warn("kmsg truncated: output malformed (%m)\n");
>> +				igt_fail(IGT_EXIT_FAILURE);
>> +			}
>> +
>> +			lstart++;
>> +			while (isspace(*lstart))
>> +				lstart++;
>> +
>> +			parse_kmsg_for_tap(lstart, lend, sublevel, failed_tests);
>> +		}
>> +	}
>> +
>> +	if (*failed_tests || *sublevel < 0)
>> +		igt_fail(IGT_EXIT_FAILURE);
>> +	else
>> +		igt_success();
>> +}
>> +
>> +/**
>> + * igt_kunit:
>> + * @module_name: the name of the module
>> + * @opts: options to load the module
>> + *
>> + * Loads the kunit module, parses its dmesg output, then unloads it
>> + */
>> +void igt_kunit(const char *module_name, const char *opts)
>> +{
>> +	struct igt_ktest tst;
>> +	char record[BUF_LEN + 1];
>> +	bool failed_tests = false;
>> +	int sublevel = 0;
>> +
>> +	record[BUF_LEN] = '\0';
>> +
>> +	/* get normalized module name */
>> +	if (igt_ktest_init(&tst, module_name) != 0) {
>> +		igt_warn("Unable to initialize ktest for %s\n", module_name);
>> +		return;
>> +	}
>> +
>> +	if (igt_ktest_begin(&tst) != 0) {
> 
> Since igt_ktest_begin() as is calls igt_require() then it may be used only 
> from inside an igt_fixture or igt_subtest block.  If the intention is to call
> igt_kunit() from an igt_subtest block, unlike igt_kselftest() which has 
> igt_fixture and igt_subtest blocks placed in its body, please document that.
> 
>> +		igt_warn("Unable to begin ktest for %s\n", module_name);
>> +
>> +		igt_ktest_fini(&tst);
>> +		return;
>> +	}
>> +
>> +	if (tst.kmsg < 0) {
>> +		igt_warn("Could not open /dev/kmsg");
>> +		goto unload;
>> +	}
>> +
>> +	if (lseek(tst.kmsg, 0, SEEK_END)) {
>> +		igt_warn("Could not seek the end of /dev/kmsg");
>> +		goto unload;
>> +	}
>> +
>> +	/* The kunit module is required for running any kunit tests */
>> +	if (igt_kmod_load("kunit", NULL) != 0) {
>> +		igt_warn("Unable to load kunit module\n");
>> +		goto unload;
>> +	}
>> +
>> +	if (igt_kmod_load(module_name, opts) != 0) {
>> +		igt_warn("Unable to load %s module\n", module_name);
>> +		goto unload;
>> +	}
>> +
>> +	igt_kunit_subtests(tst.kmsg, record, &sublevel, &failed_tests);
> 
> What's the point of passing that many temporary variable pointers to 
> igt_kunit_subtests() if we are not interested here in content of any of those 
> variables after the function returns?  That function could perfectly use its 
> own local variables for storing that data.
> 
> Besides, my comment about not using igt_require() outside of igt_fixture or 
> igt_subtest blocks also applies to igt_fail() and igt_success() called from
> igt_kunit_subtests().
> 
> Anyway, related to my comment about naming that function a parser, I think the 
> best approach would be for that parser to return a generic set of results from 
> kunit execution, then we could feed that data into an IGT specific handler 
> that would convert them to IGT results (SUCCESS, FAIL, or SKIP) as if returned 
> by a set of IGT dynamic subtests.

That sounds like a good idea to me, I might take some extra time before v3 to
do that, though. I’ll also look into your other suggestions carefully.

Thanks a lot for the review!

Cheers,
--
Isabella Basso

> Thanks,
> Janusz
> 
>> +unload:
>> +	igt_kmod_unload("kunit", 0);
>> +
>> +	igt_ktest_end(&tst);
>> +
>> +	igt_ktest_fini(&tst);
>> +}
>> +
>> static int open_parameters(const char *module_name)
>> {
>> 	char path[256];
>> diff --git a/lib/igt_kmod.h b/lib/igt_kmod.h
>> index ceb10cd0..737143c1 100644
>> --- a/lib/igt_kmod.h
>> +++ b/lib/igt_kmod.h
>> @@ -45,6 +45,8 @@ int __igt_i915_driver_unload(char **whom);
>> int igt_amdgpu_driver_load(const char *opts);
>> int igt_amdgpu_driver_unload(void);
>> 
>> +void igt_kunit(const char *module_name, const char *opts);
>> +
>> void igt_kselftests(const char *module_name,
>> 		    const char *module_options,
>> 		    const char *result_option,
>>