[PATCH i-g-t v2] lib/kunit: Read results from debugfs

[Janusz Krzysztofik <janusz.krzysztofik@linux.intel.com>]

KUnit can provide KTAP reports from test modules via debugfs files, one
per test suite.  Using that source of test results instead of extracting
them from dmesg, where they may be interleaved with other kernel messages,
seems more easy to handle and less error prone.  Switch to it.

If KUnit debugfs support is found not configured then fall back to legacy
processing path.

v2: Check validity of debugfs argument before calling kunit_get_tests()
    (Kamil),
  - replace multiple openat() + fdopen/fdopendir(), each followed by an
    error check, with less expensive fopen/opendir() of file/dir pathname
    components concatentated to a local buffer, protected from buffer
    overflow or truncation with a single check for enough buffer space
    (Lucas),
  - avoid confusing 'if' statement condition (Lucas).

Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik@linux.intel.com>
Cc: Kamil Konieczny <kamil.konieczny@linux.intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
---
 lib/igt_kmod.c | 131 +++++++++++++++++++++++++++++++++++--------------
 1 file changed, 94 insertions(+), 37 deletions(-)

diff --git a/lib/igt_kmod.c b/lib/igt_kmod.c
index 1ec9c8a602..243785873d 100644
--- a/lib/igt_kmod.c
+++ b/lib/igt_kmod.c
@@ -28,6 +28,7 @@
 #include <limits.h>
 #include <pthread.h>
 #include <signal.h>
+#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/stat.h>
@@ -39,6 +40,7 @@
 
 #include "igt_aux.h"
 #include "igt_core.h"
+#include "igt_debugfs.h"
 #include "igt_kmod.h"
 #include "igt_ktap.h"
 #include "igt_sysfs.h"
@@ -864,6 +866,19 @@ static int open_parameters(const char *module_name)
 	return open(path, O_RDONLY);
 }
 
+static void kunit_debugfs_path(char *kunit_path)
+{
+	const char *debugfs_path = igt_debugfs_mount();
+
+	if (igt_debug_on(!debugfs_path))
+		return;
+
+	if (igt_debug_on(strlen(debugfs_path) + strlen("/kunit/") >= PATH_MAX))
+		return;
+
+	strcpy(stpcpy(kunit_path, debugfs_path), "/kunit/");
+}
+
 static bool kunit_set_filtering(const char *filter_glob, const char *filter,
 				const char *filter_action)
 {
@@ -1071,21 +1086,41 @@ static void kunit_results_free(struct igt_list_head *results,
 	free(*suite_name);
 }
 
-static int kunit_get_results(struct igt_list_head *results, int kmsg_fd,
-			     struct igt_ktap_results **ktap)
+static int kunit_get_results(struct igt_list_head *results, const char *debugfs_path,
+			     const char *suite, struct igt_ktap_results **ktap)
 {
+	char results_path[PATH_MAX];
+	FILE *results_stream;
+	char *buf = NULL;
+	size_t size = 0;
+	ssize_t len;
 	int err;
 
+	if (igt_debug_on(strlen(debugfs_path) + strlen(suite) + strlen("/results") >= PATH_MAX))
+		return -ENOSPC;
+
+	strcpy(stpcpy(stpcpy(results_path, debugfs_path), suite), "/results");
+	results_stream = fopen(results_path, "r");
+	if (igt_debug_on(!results_stream))
+		return -errno;
+
 	*ktap = igt_ktap_alloc(results);
-	if (igt_debug_on(!*ktap))
-		return -ENOMEM;
+	if (igt_debug_on(!*ktap)) {
+		err = -ENOMEM;
+		goto out_fclose;
+	}
 
-	do
-		igt_debug_on((err = kunit_kmsg_result_get(results, NULL, kmsg_fd, *ktap),
-			      err && err != -EINPROGRESS));
-	while (err == -EINPROGRESS);
+	while (len = getline(&buf, &size, results_stream), len > 0) {
+		err = igt_ktap_parse(buf, *ktap);
+		if (err != -EINPROGRESS)
+			break;
+	}
+
+	free(buf);
 
 	igt_ktap_free(ktap);
+out_fclose:
+	fclose(results_stream);
 
 	return err;
 }
@@ -1101,7 +1136,13 @@ static void __igt_kunit_legacy(struct igt_ktest *tst,
 	pthread_mutexattr_t attr;
 	IGT_LIST_HEAD(results);
 	unsigned long taints;
-	int ret;
+	int flags, ret;
+
+	igt_skip_on_f(tst->kmsg < 0, "Could not open /dev/kmsg\n");
+
+	igt_skip_on((flags = fcntl(tst->kmsg, F_GETFL, 0), flags < 0));
+	igt_skip_on_f(fcntl(tst->kmsg, F_SETFL, flags & ~O_NONBLOCK) == -1,
+		      "Could not set /dev/kmsg to blocking mode\n");
 
 	igt_skip_on(lseek(tst->kmsg, 0, SEEK_END) < 0);
 
@@ -1224,30 +1265,17 @@ static void __igt_kunit_legacy(struct igt_ktest *tst,
 	igt_skip_on_f(ret, "KTAP parser failed\n");
 }
 
-static void kunit_get_tests_timeout(int signal)
-{
-	igt_skip("Timed out while trying to extract a list of KUnit test cases from /dev/kmsg\n");
-}
-
 static bool kunit_get_tests(struct igt_list_head *tests,
 			    struct igt_ktest *tst,
 			    const char *suite,
 			    const char *opts,
+			    const char *debugfs_path,
+			    DIR **debugfs_dir,
 			    struct igt_ktap_results **ktap)
 {
-	struct sigaction sigalrm = { .sa_handler = kunit_get_tests_timeout, },
-			 *saved;
 	struct igt_ktap_result *r, *rn;
+	struct dirent *subdir;
 	unsigned long taints;
-	int flags, err;
-
-	igt_skip_on_f(tst->kmsg < 0, "Could not open /dev/kmsg\n");
-
-	igt_skip_on((flags = fcntl(tst->kmsg, F_GETFL, 0), flags < 0));
-	igt_skip_on_f(fcntl(tst->kmsg, F_SETFL, flags & ~O_NONBLOCK) == -1,
-		      "Could not set /dev/kmsg to blocking mode\n");
-
-	igt_skip_on(lseek(tst->kmsg, 0, SEEK_END) < 0);
 
 	/*
 	 * To get a list of test cases provided by a kunit test module, ask the
@@ -1260,19 +1288,41 @@ static bool kunit_get_tests(struct igt_list_head *tests,
 	if (igt_debug_on(!kunit_set_filtering(suite, "module=none", "skip")))
 		return false;
 
+	*debugfs_dir = opendir(debugfs_path);
+	if (!*debugfs_dir)
+		return false;
+
+	if (!suite) {
+		seekdir(*debugfs_dir, 2);	/* directory itself and its parent */
+		errno = 0;
+		igt_skip_on_f(readdir(*debugfs_dir) || errno,
+			      "Require empty KUnit debugfs directory\n");
+		rewinddir(*debugfs_dir);
+	}
+
 	igt_skip_on(modprobe(tst->kmod, opts));
 	igt_skip_on(igt_kernel_tainted(&taints));
 
-	igt_skip_on(sigaction(SIGALRM, &sigalrm, saved));
-	alarm(10);
+	while (subdir = readdir(*debugfs_dir), subdir) {
+		if (!(subdir->d_type & DT_DIR))
+			continue;
 
-	err = kunit_get_results(tests, tst->kmsg, ktap);
+		if (!strcmp(subdir->d_name, ".") || !strcmp(subdir->d_name, ".."))
+			continue;
 
-	alarm(0);
-	igt_debug_on(sigaction(SIGALRM, saved, NULL));
+		if (suite && strcmp(subdir->d_name, suite))
+			continue;
 
-	igt_skip_on_f(err,
-		      "KTAP parser failed while getting a list of test cases\n");
+		igt_warn_on_f(kunit_get_results(tests, debugfs_path, subdir->d_name, ktap),
+			      "parsing KTAP report from test suite \"%s\" failed\n",
+			      subdir->d_name);
+
+		if (suite)
+			break;
+	}
+
+	closedir(*debugfs_dir);
+	*debugfs_dir = NULL;
 
 	igt_list_for_each_entry_safe(r, rn, tests, link)
 		igt_require_f(r->code == IGT_EXIT_SKIP,
@@ -1287,6 +1337,7 @@ static void __igt_kunit(struct igt_ktest *tst,
 			const char *subtest,
 			const char *suite,
 			const char *opts,
+			const char *debugfs_path,
 			struct igt_list_head *tests,
 			struct igt_ktap_results **ktap)
 {
@@ -1307,8 +1358,6 @@ static void __igt_kunit(struct igt_ktest *tst,
 
 			igt_skip_on(igt_kernel_tainted(&taints));
 
-			igt_fail_on(lseek(tst->kmsg, 0, SEEK_END) == -1 && errno);
-
 			igt_assert_lt(snprintf(glob, sizeof(glob), "%s.%s",
 					       t->suite_name, t->case_name),
 				      sizeof(glob));
@@ -1317,7 +1366,8 @@ static void __igt_kunit(struct igt_ktest *tst,
 			igt_assert_eq(modprobe(tst->kmod, opts), 0);
 			igt_assert_eq(igt_kernel_tainted(&taints), 0);
 
-			igt_assert_eq(kunit_get_results(&results, tst->kmsg, ktap), 0);
+			igt_assert_eq(kunit_get_results(&results, debugfs_path,
+							t->suite_name, ktap), 0);
 
 			for (i = 0; i < 2; i++) {
 				kunit_result_free(&r, &suite_name, &case_name);
@@ -1385,9 +1435,11 @@ static void __igt_kunit(struct igt_ktest *tst,
  */
 void igt_kunit(const char *module_name, const char *suite, const char *opts)
 {
+	char debugfs_path[PATH_MAX] = { '\0', };
 	struct igt_ktest tst = { .kmsg = -1, };
 	struct igt_ktap_results *ktap = NULL;
 	const char *subtest = suite;
+	DIR *debugfs_dir = NULL;
 	IGT_LIST_HEAD(tests);
 
 	/*
@@ -1435,10 +1487,12 @@ void igt_kunit(const char *module_name, const char *suite, const char *opts)
 		 *	 LTS kernels not capable of using KUnit filters for
 		 *	 listing test cases in KTAP format, with igt_require.
 		 */
-		if (!kunit_get_tests(&tests, &tst, suite, opts, &ktap))
+		kunit_debugfs_path(debugfs_path);
+		if (!*debugfs_path ||
+		    !kunit_get_tests(&tests, &tst, suite, opts, debugfs_path, &debugfs_dir, &ktap))
 			__igt_kunit_legacy(&tst, subtest, opts);
 		else
-			__igt_kunit(&tst, subtest, suite, opts, &tests, &ktap);
+			__igt_kunit(&tst, subtest, suite, opts, debugfs_path, &tests, &ktap);
 	}
 
 	igt_fixture {
@@ -1448,6 +1502,9 @@ void igt_kunit(const char *module_name, const char *suite, const char *opts)
 
 		kunit_results_free(&tests, &suite_name, &case_name);
 
+		if (debugfs_dir)
+			closedir(debugfs_dir);
+
 		igt_ktest_end(&tst);
 	}
 
-- 
2.44.0