Commit 434992bb authored by Yosry Ahmed's avatar Yosry Ahmed Committed by Alexei Starovoitov
Browse files

selftests/bpf: extend cgroup helpers 



This patch extends bpf selft cgroup_helpers [ID] n various ways:
- Add enable_controllers() that allows tests to enable all or a
  subset of controllers for a specific cgroup.
- Add join_cgroup_parent(). The cgroup workdir is based on the pid,
  therefore a spawned child cannot join the same cgroup hierarchy of the
  test through join_cgroup(). join_cgroup_parent() is used in child
  processes to join a cgroup under the parent's workdir.
- Add write_cgroup_file() and write_cgroup_file_parent() (similar to
  join_cgroup_parent() above).
- Add get_root_cgroup() for tests that need to do checks on root cgroup.
- Distinguish relative and absolute cgroup paths in function arguments.
  Now relative paths are called relative_path, and absolute paths are
  called cgroup_path.

Signed-off-by: default avatarYosry Ahmed <yosryahmed@google.com>
Signed-off-by: default avatarHao Luo <haoluo@google.com>
Link: https://lore.kernel.org/r/20220824233117.1312810-5-haoluo@google.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent a319185b

tools/testing/selftests/bpf/cgroup_helpers.c

+161 −41
Original line number Diff line number Diff line
@@ -33,49 +33,52 @@ 
#define CGROUP_MOUNT_DFLT		"/sys/fs/cgroup"

#define NETCLS_MOUNT_PATH		CGROUP_MOUNT_DFLT "/net_cls"

#define CGROUP_WORK_DIR			"/cgroup-test-work-dir"

#define format_cgroup_path(buf, path) \



#define format_cgroup_path_pid(buf, path, pid) \

	snprintf(buf, sizeof(buf), "%s%s%d%s", CGROUP_MOUNT_PATH, \

	CGROUP_WORK_DIR, getpid(), path)

	CGROUP_WORK_DIR, pid, path)



#define format_cgroup_path(buf, path) \

	format_cgroup_path_pid(buf, path, getpid())



#define format_parent_cgroup_path(buf, path) \

	format_cgroup_path_pid(buf, path, getppid())



#define format_classid_path(buf)				\

	snprintf(buf, sizeof(buf), "%s%s", NETCLS_MOUNT_PATH,	\

		 CGROUP_WORK_DIR)



/**

 * enable_all_controllers() - Enable all available cgroup v2 controllers

 *

 * Enable all available cgroup v2 controllers in order to increase

 * the code coverage.

 *

 * If successful, 0 is returned.

 */

static int enable_all_controllers(char *cgroup_path)

static int __enable_controllers(const char *cgroup_path, const char *controllers)

{

	char path[PATH_MAX + 1];

	char buf[PATH_MAX];

	char enable[PATH_MAX + 1];

	char *c, *c2;

	int fd, cfd;

	ssize_t len;



	snprintf(path, sizeof(path), "%s/cgroup.controllers", cgroup_path);

	/* If not controllers are passed, enable all available controllers */

	if (!controllers) {

		snprintf(path, sizeof(path), "%s/cgroup.controllers",

			 cgroup_path);

		fd = open(path, O_RDONLY);

		if (fd < 0) {

			log_err("Opening cgroup.controllers: %s", path);

			return 1;

		}



	len = read(fd, buf, sizeof(buf) - 1);

		len = read(fd, enable, sizeof(enable) - 1);

		if (len < 0) {

			close(fd);

			log_err("Reading cgroup.controllers: %s", path);

			return 1;

	}

	buf[len] = 0;

		} else if (len == 0) { /* No controllers to enable */

			close(fd);



	/* No controllers available? We're probably on cgroup v1. */

	if (len == 0)

			return 0;

		}

		enable[len] = 0;

		close(fd);

	} else {

		strncpy(enable, controllers, sizeof(enable));

	}



	snprintf(path, sizeof(path), "%s/cgroup.subtree_control", cgroup_path);

	cfd = open(path, O_RDWR);
@@ -84,7 +87,7 @@ static int enable_all_controllers(char *cgroup_path) 
		return 1;

	}



	for (c = strtok_r(buf, " ", &c2); c; c = strtok_r(NULL, " ", &c2)) {

	for (c = strtok_r(enable, " ", &c2); c; c = strtok_r(NULL, " ", &c2)) {

		if (dprintf(cfd, "+%s\n", c) <= 0) {

			log_err("Enabling controller %s: %s", c, path);

			close(cfd);
@@ -95,6 +98,87 @@ static int enable_all_controllers(char *cgroup_path) 
	return 0;

}



/**

 * enable_controllers() - Enable cgroup v2 controllers

 * @relative_path: The cgroup path, relative to the workdir

 * @controllers: List of controllers to enable in cgroup.controllers format

 *

 *

 * Enable given cgroup v2 controllers, if @controllers is NULL, enable all

 * available controllers.

 *

 * If successful, 0 is returned.

 */

int enable_controllers(const char *relative_path, const char *controllers)

{

	char cgroup_path[PATH_MAX + 1];



	format_cgroup_path(cgroup_path, relative_path);

	return __enable_controllers(cgroup_path, controllers);

}



static int __write_cgroup_file(const char *cgroup_path, const char *file,

			       const char *buf)

{

	char file_path[PATH_MAX + 1];

	int fd;



	snprintf(file_path, sizeof(file_path), "%s/%s", cgroup_path, file);

	fd = open(file_path, O_RDWR);

	if (fd < 0) {

		log_err("Opening %s", file_path);

		return 1;

	}



	if (dprintf(fd, "%s", buf) <= 0) {

		log_err("Writing to %s", file_path);

		close(fd);

		return 1;

	}

	close(fd);

	return 0;

}



/**

 * write_cgroup_file() - Write to a cgroup file

 * @relative_path: The cgroup path, relative to the workdir

 * @file: The name of the file in cgroupfs to write to

 * @buf: Buffer to write to the file

 *

 * Write to a file in the given cgroup's directory.

 *

 * If successful, 0 is returned.

 */

int write_cgroup_file(const char *relative_path, const char *file,

		      const char *buf)

{

	char cgroup_path[PATH_MAX - 24];



	format_cgroup_path(cgroup_path, relative_path);

	return __write_cgroup_file(cgroup_path, file, buf);

}



/**

 * write_cgroup_file_parent() - Write to a cgroup file in the parent process

 *                              workdir

 * @relative_path: The cgroup path, relative to the parent process workdir

 * @file: The name of the file in cgroupfs to write to

 * @buf: Buffer to write to the file

 *

 * Write to a file in the given cgroup's directory under the parent process

 * workdir.

 *

 * If successful, 0 is returned.

 */

int write_cgroup_file_parent(const char *relative_path, const char *file,

			     const char *buf)

{

	char cgroup_path[PATH_MAX - 24];



	format_parent_cgroup_path(cgroup_path, relative_path);

	return __write_cgroup_file(cgroup_path, file, buf);

}



/**

 * setup_cgroup_environment() - Setup the cgroup environment

 *
@@ -133,7 +217,9 @@ int setup_cgroup_environment(void) 
		return 1;

	}



	if (enable_all_controllers(cgroup_workdir))

	/* Enable all available controllers to increase test coverage */

	if (__enable_controllers(CGROUP_MOUNT_PATH, NULL) ||

	    __enable_controllers(cgroup_workdir, NULL))

		return 1;



	return 0;
@@ -173,7 +259,7 @@ static int join_cgroup_from_top(const char *cgroup_path) 


/**

 * join_cgroup() - Join a cgroup

 * @path: The cgroup path, relative to the workdir, to join

 * @relative_path: The cgroup path, relative to the workdir, to join

 *

 * This function expects a cgroup to already be created, relative to the cgroup

 * work dir, and it joins it. For example, passing "/my-cgroup" as the path
@@ -182,11 +268,27 @@ static int join_cgroup_from_top(const char *cgroup_path) 
 *

 * On success, it returns 0, otherwise on failure it returns 1.

 */

int join_cgroup(const char *path)

int join_cgroup(const char *relative_path)

{

	char cgroup_path[PATH_MAX + 1];



	format_cgroup_path(cgroup_path, path);

	format_cgroup_path(cgroup_path, relative_path);

	return join_cgroup_from_top(cgroup_path);

}



/**

 * join_parent_cgroup() - Join a cgroup in the parent process workdir

 * @relative_path: The cgroup path, relative to parent process workdir, to join

 *

 * See join_cgroup().

 *

 * On success, it returns 0, otherwise on failure it returns 1.

 */

int join_parent_cgroup(const char *relative_path)

{

	char cgroup_path[PATH_MAX + 1];



	format_parent_cgroup_path(cgroup_path, relative_path);

	return join_cgroup_from_top(cgroup_path);

}
@@ -212,9 +314,27 @@ void cleanup_cgroup_environment(void) 
	nftw(cgroup_workdir, nftwfunc, WALK_FD_LIMIT, FTW_DEPTH | FTW_MOUNT);

}



/**

 * get_root_cgroup() - Get the FD of the root cgroup

 *

 * On success, it returns the file descriptor. On failure, it returns -1.

 * If there is a failure, it prints the error to stderr.

 */

int get_root_cgroup(void)

{

	int fd;



	fd = open(CGROUP_MOUNT_PATH, O_RDONLY);

	if (fd < 0) {

		log_err("Opening root cgroup");

		return -1;

	}

	return fd;

}



/**

 * create_and_get_cgroup() - Create a cgroup, relative to workdir, and get the FD

 * @path: The cgroup path, relative to the workdir, to join

 * @relative_path: The cgroup path, relative to the workdir, to join

 *

 * This function creates a cgroup under the top level workdir and returns the

 * file descriptor. It is idempotent.
@@ -222,14 +342,14 @@ void cleanup_cgroup_environment(void) 
 * On success, it returns the file descriptor. On failure it returns -1.

 * If there is a failure, it prints the error to stderr.

 */

int create_and_get_cgroup(const char *path)

int create_and_get_cgroup(const char *relative_path)

{

	char cgroup_path[PATH_MAX + 1];

	int fd;



	format_cgroup_path(cgroup_path, path);

	format_cgroup_path(cgroup_path, relative_path);

	if (mkdir(cgroup_path, 0777) && errno != EEXIST) {

		log_err("mkdiring cgroup %s .. %s", path, cgroup_path);

		log_err("mkdiring cgroup %s .. %s", relative_path, cgroup_path);

		return -1;

	}
@@ -244,13 +364,13 @@ int create_and_get_cgroup(const char *path) 


/**

 * get_cgroup_id() - Get cgroup id for a particular cgroup path

 * @path: The cgroup path, relative to the workdir, to join

 * @relative_path: The cgroup path, relative to the workdir, to join

 *

 * On success, it returns the cgroup id. On failure it returns 0,

 * which is an invalid cgroup id.

 * If there is a failure, it prints the error to stderr.

 */

unsigned long long get_cgroup_id(const char *path)

unsigned long long get_cgroup_id(const char *relative_path)

{

	int dirfd, err, flags, mount_id, fhsize;

	union {
@@ -261,7 +381,7 @@ unsigned long long get_cgroup_id(const char *path) 
	struct file_handle *fhp, *fhp2;

	unsigned long long ret = 0;



	format_cgroup_path(cgroup_workdir, path);

	format_cgroup_path(cgroup_workdir, relative_path);



	dirfd = AT_FDCWD;

	flags = 0;

tools/testing/selftests/bpf/cgroup_helpers.h

+13 −6
Original line number Diff line number Diff line
@@ -10,11 +10,18 @@ 
	__FILE__, __LINE__, clean_errno(), ##__VA_ARGS__)



/* cgroupv2 related */

int cgroup_setup_and_join(const char *path);

int create_and_get_cgroup(const char *path);

unsigned long long get_cgroup_id(const char *path);



int join_cgroup(const char *path);

int enable_controllers(const char *relative_path, const char *controllers);

int write_cgroup_file(const char *relative_path, const char *file,

		      const char *buf);

int write_cgroup_file_parent(const char *relative_path, const char *file,

			     const char *buf);

int cgroup_setup_and_join(const char *relative_path);

int get_root_cgroup(void);

int create_and_get_cgroup(const char *relative_path);

unsigned long long get_cgroup_id(const char *relative_path);



int join_cgroup(const char *relative_path);

int join_parent_cgroup(const char *relative_path);



int setup_cgroup_environment(void);

void cleanup_cgroup_environment(void);