thread_map.c

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// SPDX-License-Identifier: GPL-2.0
#include <dirent.h>
#include <errno.h>
#include <limits.h>
#include <stdbool.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include "string2.h"
#include "strlist.h"
#include <string.h>
#include <api/fs/fs.h>
#include "asm/bug.h"
#include "thread_map.h"
#include "util.h"
#include "debug.h"
#include "event.h"

/* Skip "." and ".." directories */
static int filter(const struct dirent *dir)
{
    if (dir->d_name[0] == '.')
        return 0;
    else
        return 1;
}

static void thread_map__reset(struct thread_map *map, int start, int nr)
{
    size_t size = (nr - start) * sizeof(map->map[0]);

    memset(&map->map[start], 0, size);
    map->err_thread = -1;
}

static struct thread_map *thread_map__realloc(struct thread_map *map, int nr)
{
    size_t size = sizeof(*map) + sizeof(map->map[0]) * nr;
    int start = map ? map->nr : 0;

    map = realloc(map, size);
    /*
     * We only realloc to add more items, let's reset new items.
     */
    if (map)
        thread_map__reset(map, start, nr);

    return map;
}

#define thread_map__alloc(__nr) thread_map__realloc(NULL, __nr)

struct thread_map *thread_map__new_by_pid(pid_t pid)
{
    struct thread_map *threads;
    char name[256];
    int items;
    struct dirent **namelist = NULL;
    int i;

    sprintf(name, "/proc/%d/task", pid);
    items = scandir(name, &namelist, filter, NULL);
    if (items <= 0)
        return NULL;

    threads = thread_map__alloc(items);
    if (threads != NULL) {
        for (i = 0; i < items; i++)
            thread_map__set_pid(threads, i, atoi(namelist[i]->d_name));
        threads->nr = items;
        refcount_set(&threads->refcnt, 1);
    }

    for (i=0; i<items; i++)
        zfree(&namelist[i]);
    free(namelist);

    return threads;
}

struct thread_map *thread_map__new_by_tid(pid_t tid)
{
    struct thread_map *threads = thread_map__alloc(1);

    if (threads != NULL) {
        thread_map__set_pid(threads, 0, tid);
        threads->nr = 1;
        refcount_set(&threads->refcnt, 1);
    }

    return threads;
}

static struct thread_map *__thread_map__new_all_cpus(uid_t uid)
{
    DIR *proc;
    int max_threads = 32, items, i;
    char path[NAME_MAX + 1 + 6];
    struct dirent *dirent, **namelist = NULL;
    struct thread_map *threads = thread_map__alloc(max_threads);

    if (threads == NULL)
        goto out;

    proc = opendir("/proc");
    if (proc == NULL)
        goto out_free_threads;

    threads->nr = 0;
    refcount_set(&threads->refcnt, 1);

    while ((dirent = readdir(proc)) != NULL) {
        char *end;
        bool grow = false;
        pid_t pid = strtol(dirent->d_name, &end, 10);

        if (*end) /* only interested in proper numerical dirents */
            continue;

        snprintf(path, sizeof(path), "/proc/%s", dirent->d_name);

        if (uid != UINT_MAX) {
            struct stat st;

            if (stat(path, &st) != 0 || st.st_uid != uid)
                continue;
        }

        snprintf(path, sizeof(path), "/proc/%d/task", pid);
        items = scandir(path, &namelist, filter, NULL);
        if (items <= 0)
            goto out_free_closedir;

        while (threads->nr + items >= max_threads) {
            max_threads *= 2;
            grow = true;
        }

        if (grow) {
            struct thread_map *tmp;

            tmp = thread_map__realloc(threads, max_threads);
            if (tmp == NULL)
                goto out_free_namelist;

            threads = tmp;
        }

        for (i = 0; i < items; i++) {
            thread_map__set_pid(threads, threads->nr + i,
                        atoi(namelist[i]->d_name));
        }

        for (i = 0; i < items; i++)
            zfree(&namelist[i]);
        free(namelist);

        threads->nr += items;
    }

out_closedir:
    closedir(proc);
out:
    return threads;

out_free_threads:
    free(threads);
    return NULL;

out_free_namelist:
    for (i = 0; i < items; i++)
        zfree(&namelist[i]);
    free(namelist);

out_free_closedir:
    zfree(&threads);
    goto out_closedir;
}

struct thread_map *thread_map__new_all_cpus(void)
{
    return __thread_map__new_all_cpus(UINT_MAX);
}

struct thread_map *thread_map__new_by_uid(uid_t uid)
{
    return __thread_map__new_all_cpus(uid);
}

struct thread_map *thread_map__new(pid_t pid, pid_t tid, uid_t uid)
{
    if (pid != -1)
        return thread_map__new_by_pid(pid);

    if (tid == -1 && uid != UINT_MAX)
        return thread_map__new_by_uid(uid);

    return thread_map__new_by_tid(tid);
}

static struct thread_map *thread_map__new_by_pid_str(const char *pid_str)
{
    struct thread_map *threads = NULL, *nt;
    char name[256];
    int items, total_tasks = 0;
    struct dirent **namelist = NULL;
    int i, j = 0;
    pid_t pid, prev_pid = INT_MAX;
    char *end_ptr;
    struct str_node *pos;
    struct strlist_config slist_config = { .dont_dupstr = true, };
    struct strlist *slist = strlist__new(pid_str, &slist_config);

    if (!slist)
        return NULL;

    strlist__for_each_entry(pos, slist) {
        pid = strtol(pos->s, &end_ptr, 10);

        if (pid == INT_MIN || pid == INT_MAX ||
            (*end_ptr != '\0' && *end_ptr != ','))
            goto out_free_threads;

        if (pid == prev_pid)
            continue;

        sprintf(name, "/proc/%d/task", pid);
        items = scandir(name, &namelist, filter, NULL);
        if (items <= 0)
            goto out_free_threads;

        total_tasks += items;
        nt = thread_map__realloc(threads, total_tasks);
        if (nt == NULL)
            goto out_free_namelist;

        threads = nt;

        for (i = 0; i < items; i++) {
            thread_map__set_pid(threads, j++, atoi(namelist[i]->d_name));
            zfree(&namelist[i]);
        }
        threads->nr = total_tasks;
        free(namelist);
    }

out:
    strlist__delete(slist);
    if (threads)
        refcount_set(&threads->refcnt, 1);
    return threads;

out_free_namelist:
    for (i = 0; i < items; i++)
        zfree(&namelist[i]);
    free(namelist);

out_free_threads:
    zfree(&threads);
    goto out;
}

struct thread_map *thread_map__new_dummy(void)
{
    struct thread_map *threads = thread_map__alloc(1);

    if (threads != NULL) {
        thread_map__set_pid(threads, 0, -1);
        threads->nr = 1;
        refcount_set(&threads->refcnt, 1);
    }
    return threads;
}

struct thread_map *thread_map__new_by_tid_str(const char *tid_str)
{
    struct thread_map *threads = NULL, *nt;
    int ntasks = 0;
    pid_t tid, prev_tid = INT_MAX;
    char *end_ptr;
    struct str_node *pos;
    struct strlist_config slist_config = { .dont_dupstr = true, };
    struct strlist *slist;

    /* perf-stat expects threads to be generated even if tid not given */
    if (!tid_str)
        return thread_map__new_dummy();

    slist = strlist__new(tid_str, &slist_config);
    if (!slist)
        return NULL;

    strlist__for_each_entry(pos, slist) {
        tid = strtol(pos->s, &end_ptr, 10);

        if (tid == INT_MIN || tid == INT_MAX ||
            (*end_ptr != '\0' && *end_ptr != ','))
            goto out_free_threads;

        if (tid == prev_tid)
            continue;

        ntasks++;
        nt = thread_map__realloc(threads, ntasks);

        if (nt == NULL)
            goto out_free_threads;

        threads = nt;
        thread_map__set_pid(threads, ntasks - 1, tid);
        threads->nr = ntasks;
    }
out:
    if (threads)
        refcount_set(&threads->refcnt, 1);
    return threads;

out_free_threads:
    zfree(&threads);
    strlist__delete(slist);
    goto out;
}

struct thread_map *thread_map__new_str(const char *pid, const char *tid,
                       uid_t uid, bool all_threads)
{
    if (pid)
        return thread_map__new_by_pid_str(pid);

    if (!tid && uid != UINT_MAX)
        return thread_map__new_by_uid(uid);

    if (all_threads)
        return thread_map__new_all_cpus();

    return thread_map__new_by_tid_str(tid);
}

static void thread_map__delete(struct thread_map *threads)
{
    if (threads) {
        int i;

        WARN_ONCE(refcount_read(&threads->refcnt) != 0,
              "thread map refcnt unbalanced\n");
        for (i = 0; i < threads->nr; i++)
            free(thread_map__comm(threads, i));
        free(threads);
    }
}

struct thread_map *thread_map__get(struct thread_map *map)
{
    if (map)
        refcount_inc(&map->refcnt);
    return map;
}

void thread_map__put(struct thread_map *map)
{
    if (map && refcount_dec_and_test(&map->refcnt))
        thread_map__delete(map);
}

size_t thread_map__fprintf(struct thread_map *threads, FILE *fp)
{
    int i;
    size_t printed = fprintf(fp, "%d thread%s: ",
                 threads->nr, threads->nr > 1 ? "s" : "");
    for (i = 0; i < threads->nr; ++i)
        printed += fprintf(fp, "%s%d", i ? ", " : "", thread_map__pid(threads, i));

    return printed + fprintf(fp, "\n");
}

static int get_comm(char **comm, pid_t pid)
{
    char *path;
    size_t size;
    int err;

    if (asprintf(&path, "%s/%d/comm", procfs__mountpoint(), pid) == -1)
        return -ENOMEM;

    err = filename__read_str(path, comm, &size);
    if (!err) {
        /*
         * We're reading 16 bytes, while filename__read_str
         * allocates data per BUFSIZ bytes, so we can safely
         * mark the end of the string.
         */
        (*comm)[size] = 0;
        rtrim(*comm);
    }

    free(path);
    return err;
}

static void comm_init(struct thread_map *map, int i)
{
    pid_t pid = thread_map__pid(map, i);
    char *comm = NULL;

    /* dummy pid comm initialization */
    if (pid == -1) {
        map->map[i].comm = strdup("dummy");
        return;
    }

    /*
     * The comm name is like extra bonus ;-),
     * so just warn if we fail for any reason.
     */
    if (get_comm(&comm, pid))
        pr_warning("Couldn't resolve comm name for pid %d\n", pid);

    map->map[i].comm = comm;
}

void thread_map__read_comms(struct thread_map *threads)
{
    int i;

    for (i = 0; i < threads->nr; ++i)
        comm_init(threads, i);
}

static void thread_map__copy_event(struct thread_map *threads,
                   struct thread_map_event *event)
{
    unsigned i;

    threads->nr = (int) event->nr;

    for (i = 0; i < event->nr; i++) {
        thread_map__set_pid(threads, i, (pid_t) event->entries[i].pid);
        threads->map[i].comm = strndup(event->entries[i].comm, 16);
    }

    refcount_set(&threads->refcnt, 1);
}

struct thread_map *thread_map__new_event(struct thread_map_event *event)
{
    struct thread_map *threads;

    threads = thread_map__alloc(event->nr);
    if (threads)
        thread_map__copy_event(threads, event);

    return threads;
}

bool thread_map__has(struct thread_map *threads, pid_t pid)
{
    int i;

    for (i = 0; i < threads->nr; ++i) {
        if (threads->map[i].pid == pid)
            return true;
    }

    return false;
}

int thread_map__remove(struct thread_map *threads, int idx)
{
    int i;

    if (threads->nr < 1)
        return -EINVAL;

    if (idx >= threads->nr)
        return -EINVAL;

    /*
     * Free the 'idx' item and shift the rest up.
     */
    free(threads->map[idx].comm);

    for (i = idx; i < threads->nr - 1; i++)
        threads->map[i] = threads->map[i + 1];

    threads->nr--;
    return 0;
}