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    Subject[RESEND PATCH bpf-next v9 4/5] selftests/bpf: extend cgroup helpers
    From
    From: Yosry Ahmed <yosryahmed@google.com>

    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: Yosry Ahmed <yosryahmed@google.com>
    Signed-off-by: Hao Luo <haoluo@google.com>
    ---
    tools/testing/selftests/bpf/cgroup_helpers.c | 202 +++++++++++++++----
    tools/testing/selftests/bpf/cgroup_helpers.h | 19 +-
    2 files changed, 174 insertions(+), 47 deletions(-)

    diff --git a/tools/testing/selftests/bpf/cgroup_helpers.c b/tools/testing/selftests/bpf/cgroup_helpers.c
    index 9d59c3990ca8..e914cc45b766 100644
    --- a/tools/testing/selftests/bpf/cgroup_helpers.c
    +++ b/tools/testing/selftests/bpf/cgroup_helpers.c
    @@ -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);
    - fd = open(path, O_RDONLY);
    - if (fd < 0) {
    - log_err("Opening cgroup.controllers: %s", path);
    - return 1;
    - }
    -
    - len = read(fd, buf, sizeof(buf) - 1);
    - if (len < 0) {
    + /* 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, enable, sizeof(enable) - 1);
    + if (len < 0) {
    + close(fd);
    + log_err("Reading cgroup.controllers: %s", path);
    + return 1;
    + } else if (len == 0) { /* No controllers to enable */
    + close(fd);
    + return 0;
    + }
    + enable[len] = 0;
    close(fd);
    - log_err("Reading cgroup.controllers: %s", path);
    - return 1;
    + } else {
    + strncpy(enable, controllers, sizeof(enable));
    }
    - buf[len] = 0;
    - close(fd);
    -
    - /* No controllers available? We're probably on cgroup v1. */
    - if (len == 0)
    - return 0;

    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, 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_cgroup_path(cgroup_path, path);
    + 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;
    diff --git a/tools/testing/selftests/bpf/cgroup_helpers.h b/tools/testing/selftests/bpf/cgroup_helpers.h
    index fcc9cb91b211..3358734356ab 100644
    --- a/tools/testing/selftests/bpf/cgroup_helpers.h
    +++ b/tools/testing/selftests/bpf/cgroup_helpers.h
    @@ -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);
    @@ -26,4 +33,4 @@ int join_classid(void);
    int setup_classid_environment(void);
    void cleanup_classid_environment(void);

    -#endif /* __CGROUP_HELPERS_H */
    \ No newline at end of file
    +#endif /* __CGROUP_HELPERS_H */
    --
    2.37.1.595.g718a3a8f04-goog
    \
     
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      Last update: 2022-08-25 01:33    [W:3.255 / U:0.008 seconds]
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