add new system file

hc

2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c

 kernel/tools/testing/selftests/bpf/cgroup_helpers.c
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@@ -34,6 +34,60 @@
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 		 CGROUP_WORK_DIR, path)
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 /**
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+ * enable_all_controllers() - Enable all available cgroup v2 controllers
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+ *
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+ * Enable all available cgroup v2 controllers in order to increase
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+ * the code coverage.
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+ *
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+ * If successful, 0 is returned.
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+ */
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+static int enable_all_controllers(char *cgroup_path)
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+{
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+	char path[PATH_MAX + 1];
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+	char buf[PATH_MAX];
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+	char *c, *c2;
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+	int fd, cfd;
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+	ssize_t len;
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+
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+	snprintf(path, sizeof(path), "%s/cgroup.controllers", cgroup_path);
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+	fd = open(path, O_RDONLY);
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+	if (fd < 0) {
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+		log_err("Opening cgroup.controllers: %s", path);
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+		return 1;
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+	}
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+
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+	len = read(fd, buf, sizeof(buf) - 1);
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+	if (len < 0) {
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+		close(fd);
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+		log_err("Reading cgroup.controllers: %s", path);
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+		return 1;
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+	}
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+	buf[len] = 0;
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+	close(fd);
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+
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+	/* No controllers available? We're probably on cgroup v1. */
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+	if (len == 0)
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+		return 0;
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+
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+	snprintf(path, sizeof(path), "%s/cgroup.subtree_control", cgroup_path);
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+	cfd = open(path, O_RDWR);
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+	if (cfd < 0) {
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+		log_err("Opening cgroup.subtree_control: %s", path);
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+		return 1;
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+	}
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+
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+	for (c = strtok_r(buf, " ", &c2); c; c = strtok_r(NULL, " ", &c2)) {
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+		if (dprintf(cfd, "+%s\n", c) <= 0) {
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+			log_err("Enabling controller %s: %s", c, path);
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+			close(cfd);
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+			return 1;
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+		}
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+	}
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+	close(cfd);
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+	return 0;
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+}
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+
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+/**
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  * setup_cgroup_environment() - Setup the cgroup environment
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  *
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  * After calling this function, cleanup_cgroup_environment should be called
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@@ -70,6 +124,9 @@
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 		log_err("mkdir cgroup work dir");
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 		return 1;
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 	}
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+
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+	if (enable_all_controllers(cgroup_workdir))
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+		return 1;
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 	return 0;
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 }
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@@ -155,7 +212,7 @@
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  * This function creates a cgroup under the top level workdir and returns the
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  * file descriptor. It is idempotent.
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  *
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- * On success, it returns the file descriptor. On failure it returns 0.
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+ * On success, it returns the file descriptor. On failure it returns -1.
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  * If there is a failure, it prints the error to stderr.
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  */
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 int create_and_get_cgroup(const char *path)
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@@ -166,13 +223,13 @@
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 	format_cgroup_path(cgroup_path, path);
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 	if (mkdir(cgroup_path, 0777) && errno != EEXIST) {
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 		log_err("mkdiring cgroup %s .. %s", path, cgroup_path);
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-		return 0;
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+		return -1;
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 	}
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 	fd = open(cgroup_path, O_RDONLY);
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 	if (fd < 0) {
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 		log_err("Opening Cgroup");
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-		return 0;
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+		return -1;
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 	}
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 	return fd;
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@@ -233,3 +290,26 @@
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 	free(fhp);
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 	return ret;
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 }
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+
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+int cgroup_setup_and_join(const char *path) {
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+	int cg_fd;
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+
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+	if (setup_cgroup_environment()) {
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+		fprintf(stderr, "Failed to setup cgroup environment\n");
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+		return -EINVAL;
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+	}
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+
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+	cg_fd = create_and_get_cgroup(path);
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+	if (cg_fd < 0) {
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+		fprintf(stderr, "Failed to create test cgroup\n");
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+		cleanup_cgroup_environment();
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+		return cg_fd;
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+	}
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+
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+	if (join_cgroup(path)) {
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+		fprintf(stderr, "Failed to join cgroup\n");
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+		cleanup_cgroup_environment();
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+		return -EINVAL;
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+	}
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+	return cg_fd;
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+}