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Subject[PATCH 4/5] selftests: cgroup: Add task migration tests
Date
Add two new tests that verify that thread and threadgroup migrations
work as expected.

Signed-off-by: Michal Koutný <mkoutny@suse.com>
---
tools/testing/selftests/cgroup/Makefile | 2 +-
tools/testing/selftests/cgroup/cgroup_util.c | 26 ++++
tools/testing/selftests/cgroup/cgroup_util.h | 2 +
tools/testing/selftests/cgroup/test_core.c | 146 +++++++++++++++++++
4 files changed, 175 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/cgroup/Makefile b/tools/testing/selftests/cgroup/Makefile
index 8d369b6a2069..1c9179400be0 100644
--- a/tools/testing/selftests/cgroup/Makefile
+++ b/tools/testing/selftests/cgroup/Makefile
@@ -1,5 +1,5 @@
# SPDX-License-Identifier: GPL-2.0
-CFLAGS += -Wall
+CFLAGS += -Wall -pthread

all:

diff --git a/tools/testing/selftests/cgroup/cgroup_util.c b/tools/testing/selftests/cgroup/cgroup_util.c
index f6573eac1365..8f7131dcf1ff 100644
--- a/tools/testing/selftests/cgroup/cgroup_util.c
+++ b/tools/testing/selftests/cgroup/cgroup_util.c
@@ -158,6 +158,22 @@ long cg_read_key_long(const char *cgroup, const char *control, const char *key)
return atol(ptr + strlen(key));
}

+long cg_read_lc(const char *cgroup, const char *control)
+{
+ char buf[PAGE_SIZE];
+ const char delim[] = "\n";
+ char *line;
+ long cnt = 0;
+
+ if (cg_read(cgroup, control, buf, sizeof(buf)))
+ return -1;
+
+ for (line = strtok(buf, delim); line; line = strtok(NULL, delim))
+ cnt++;
+
+ return cnt;
+}
+
int cg_write(const char *cgroup, const char *control, char *buf)
{
char path[PATH_MAX];
@@ -424,3 +440,13 @@ ssize_t proc_read_text(int pid, bool thread, const char *item, char *buf, size_t

return read_text(path, buf, size);
}
+
+int proc_read_strstr(int pid, bool thread, const char *item, const char *needle)
+{
+ char buf[PAGE_SIZE];
+
+ if (proc_read_text(pid, thread, item, buf, sizeof(buf)) < 0)
+ return -1;
+
+ return strstr(buf, needle) ? 0 : -1;
+}
diff --git a/tools/testing/selftests/cgroup/cgroup_util.h b/tools/testing/selftests/cgroup/cgroup_util.h
index 27ff21d82af1..49c54fbdb229 100644
--- a/tools/testing/selftests/cgroup/cgroup_util.h
+++ b/tools/testing/selftests/cgroup/cgroup_util.h
@@ -30,6 +30,7 @@ extern int cg_read_strstr(const char *cgroup, const char *control,
const char *needle);
extern long cg_read_long(const char *cgroup, const char *control);
long cg_read_key_long(const char *cgroup, const char *control, const char *key);
+extern long cg_read_lc(const char *cgroup, const char *control);
extern int cg_write(const char *cgroup, const char *control, char *buf);
extern int cg_run(const char *cgroup,
int (*fn)(const char *cgroup, void *arg),
@@ -48,3 +49,4 @@ extern int set_oom_adj_score(int pid, int score);
extern int cg_wait_for_proc_count(const char *cgroup, int count);
extern int cg_killall(const char *cgroup);
extern ssize_t proc_read_text(int pid, bool thread, const char *item, char *buf, size_t size);
+extern int proc_read_strstr(int pid, bool thread, const char *item, const char *needle);
diff --git a/tools/testing/selftests/cgroup/test_core.c b/tools/testing/selftests/cgroup/test_core.c
index 79053a4f4783..c5ca669feb2b 100644
--- a/tools/testing/selftests/cgroup/test_core.c
+++ b/tools/testing/selftests/cgroup/test_core.c
@@ -5,6 +5,9 @@
#include <unistd.h>
#include <stdio.h>
#include <errno.h>
+#include <signal.h>
+#include <string.h>
+#include <pthread.h>

#include "../kselftest.h"
#include "cgroup_util.h"
@@ -354,6 +357,147 @@ static int test_cgcore_internal_process_constraint(const char *root)
return ret;
}

+static void *dummy_thread_fn(void *arg)
+{
+ return (void *)(size_t)pause();
+}
+
+/*
+ * Test threadgroup migration.
+ * All threads of a process are migrated together.
+ */
+static int test_cgcore_proc_migration(const char *root)
+{
+ int ret = KSFT_FAIL;
+ int t, c_threads, n_threads = 13;
+ char *src = NULL, *dst = NULL;
+ pthread_t threads[n_threads];
+
+ src = cg_name(root, "cg_src");
+ dst = cg_name(root, "cg_dst");
+ if (!src || !dst)
+ goto cleanup;
+
+ if (cg_create(src))
+ goto cleanup;
+ if (cg_create(dst))
+ goto cleanup;
+
+ if (cg_enter_current(src))
+ goto cleanup;
+
+ for (c_threads = 0; c_threads < n_threads; ++c_threads) {
+ if (pthread_create(&threads[c_threads], NULL, dummy_thread_fn, NULL))
+ goto cleanup;
+ }
+
+ cg_enter_current(dst);
+ if (cg_read_lc(dst, "cgroup.threads") != n_threads + 1)
+ goto cleanup;
+
+ ret = KSFT_PASS;
+
+cleanup:
+ for (t = 0; t < c_threads; ++t) {
+ pthread_cancel(threads[t]);
+ }
+
+ for (t = 0; t < c_threads; ++t) {
+ pthread_join(threads[t], NULL);
+ }
+
+ cg_enter_current(root);
+
+ if (dst)
+ cg_destroy(dst);
+ if (src)
+ cg_destroy(src);
+ free(dst);
+ free(src);
+ return ret;
+}
+
+static void *migrating_thread_fn(void *arg)
+{
+ int g, i, n_iterations = 1000;
+ char **grps = arg;
+ char lines[3][PATH_MAX];
+
+ for (g = 1; g < 3; ++g)
+ snprintf(lines[g], sizeof(lines[g]), "0::%s", grps[g] + strlen(grps[0]));
+
+ for (i = 0; i < n_iterations; ++i) {
+ cg_enter_current_thread(grps[(i % 2) + 1]);
+
+ if (proc_read_strstr(0, 1, "cgroup", lines[(i % 2) + 1]))
+ return (void *)-1;
+ }
+ return NULL;
+}
+
+/*
+ * Test single thread migration.
+ * Threaded cgroups allow successful migration of a thread.
+ */
+static int test_cgcore_thread_migration(const char *root)
+{
+ int ret = KSFT_FAIL;
+ char *dom = NULL;
+ char line[PATH_MAX];
+ char *grps[3] = { (char *)root, NULL, NULL };
+ pthread_t thr;
+ void *retval;
+
+ dom = cg_name(root, "cg_dom");
+ grps[1] = cg_name(root, "cg_dom/cg_src");
+ grps[2] = cg_name(root, "cg_dom/cg_dst");
+ if (!grps[1] || !grps[2] || !dom)
+ goto cleanup;
+
+ if (cg_create(dom))
+ goto cleanup;
+ if (cg_create(grps[1]))
+ goto cleanup;
+ if (cg_create(grps[2]))
+ goto cleanup;
+
+ if (cg_write(grps[1], "cgroup.type", "threaded"))
+ goto cleanup;
+ if (cg_write(grps[2], "cgroup.type", "threaded"))
+ goto cleanup;
+
+ if (cg_enter_current(grps[1]))
+ goto cleanup;
+
+ if (pthread_create(&thr, NULL, migrating_thread_fn, grps))
+ goto cleanup;
+
+ if (pthread_join(thr, &retval))
+ goto cleanup;
+
+ if (retval)
+ goto cleanup;
+
+ snprintf(line, sizeof(line), "0::%s", grps[1] + strlen(grps[0]));
+ if (proc_read_strstr(0, 1, "cgroup", line))
+ goto cleanup;
+
+ ret = KSFT_PASS;
+
+cleanup:
+ cg_enter_current(root);
+ if (grps[2])
+ cg_destroy(grps[2]);
+ if (grps[1])
+ cg_destroy(grps[1]);
+ if (dom)
+ cg_destroy(dom);
+ free(grps[2]);
+ free(grps[1]);
+ free(dom);
+ return ret;
+}
+
#define T(x) { x, #x }
struct corecg_test {
int (*fn)(const char *root);
@@ -366,6 +510,8 @@ struct corecg_test {
T(test_cgcore_parent_becomes_threaded),
T(test_cgcore_invalid_domain),
T(test_cgcore_populated),
+ T(test_cgcore_proc_migration),
+ T(test_cgcore_thread_migration),
};
#undef T

--
2.21.0
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