cgroups: move cgroup_event_listener.c to tools/cgroup

Move the cgroup_event_listener.c tool from Documentation into the new
tools/cgroup directory.

This change involves wiring cgroup_event_listener.c into the tools/
make system so that is can be built with:
  $ make tools/cgroup

Signed-off-by: Greg Thelen <gthelen@google.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

3 files changed, 1 insertions, 114 deletions

diff --git a/Documentation/cgroups/00-INDEX b/Documentation/cgroups/00-INDEX
index f78b90a35ad0..f5635a09c3f6 100644
--- a/Documentation/cgroups/00-INDEX
+++ b/Documentation/cgroups/00-INDEX
@@ -4,8 +4,6 @@ blkio-controller.txt
         - Description for Block IO Controller, implementation and usage details.
 cgroups.txt
         - Control Groups definition, implementation details, examples and API.
-cgroup_event_listener.c
-        - A user program for cgroup listener.
 cpuacct.txt
         - CPU Accounting Controller; account CPU usage for groups of tasks.
 cpusets.txt
diff --git a/Documentation/cgroups/cgroup_event_listener.c b/Documentation/cgroups/cgroup_event_listener.c
deleted file mode 100644
index 3e082f96dc12..000000000000
--- a/Documentation/cgroups/cgroup_event_listener.c
+++ /dev/null
@@ -1,110 +0,0 @@
-/*
- * cgroup_event_listener.c - Simple listener of cgroup events
- *
- * Copyright (C) Kirill A. Shutemov <kirill@shutemov.name>
- */
-
-#include <assert.h>
-#include <errno.h>
-#include <fcntl.h>
-#include <libgen.h>
-#include <limits.h>
-#include <stdio.h>
-#include <string.h>
-#include <unistd.h>
-
-#include <sys/eventfd.h>
-
-#define USAGE_STR "Usage: cgroup_event_listener <path-to-control-file> <args>\n"
-
-int main(int argc, char **argv)
-{
-        int efd = -1;
-        int cfd = -1;
-        int event_control = -1;
-        char event_control_path[PATH_MAX];
-        char line[LINE_MAX];
-        int ret;
-
-        if (argc != 3) {
-                fputs(USAGE_STR, stderr);
-                return 1;
-        }
-
-        cfd = open(argv[1], O_RDONLY);
-        if (cfd == -1) {
-                fprintf(stderr, "Cannot open %s: %s\n", argv[1],
-                                strerror(errno));
-                goto out;
-        }
-
-        ret = snprintf(event_control_path, PATH_MAX, "%s/cgroup.event_control",
-                        dirname(argv[1]));
-        if (ret >= PATH_MAX) {
-                fputs("Path to cgroup.event_control is too long\n", stderr);
-                goto out;
-        }
-
-        event_control = open(event_control_path, O_WRONLY);
-        if (event_control == -1) {
-                fprintf(stderr, "Cannot open %s: %s\n", event_control_path,
-                                strerror(errno));
-                goto out;
-        }
-
-        efd = eventfd(0, 0);
-        if (efd == -1) {
-                perror("eventfd() failed");
-                goto out;
-        }
-
-        ret = snprintf(line, LINE_MAX, "%d %d %s", efd, cfd, argv[2]);
-        if (ret >= LINE_MAX) {
-                fputs("Arguments string is too long\n", stderr);
-                goto out;
-        }
-
-        ret = write(event_control, line, strlen(line) + 1);
-        if (ret == -1) {
-                perror("Cannot write to cgroup.event_control");
-                goto out;
-        }
-
-        while (1) {
-                uint64_t result;
-
-                ret = read(efd, &result, sizeof(result));
-                if (ret == -1) {
-                        if (errno == EINTR)
-                                continue;
-                        perror("Cannot read from eventfd");
-                        break;
-                }
-                assert(ret == sizeof(result));
-
-                ret = access(event_control_path, W_OK);
-                if ((ret == -1) && (errno == ENOENT)) {
-                                puts("The cgroup seems to have removed.");
-                                ret = 0;
-                                break;
-                }
-
-                if (ret == -1) {
-                        perror("cgroup.event_control "
-                                        "is not accessible any more");
-                        break;
-                }
-
-                printf("%s %s: crossed\n", argv[1], argv[2]);
-        }
-
-out:
-        if (efd >= 0)
-                close(efd);
-        if (event_control >= 0)
-                close(event_control);
-        if (cfd >= 0)
-                close(cfd);
-
-        return (ret != 0);
-}
diff --git a/Documentation/cgroups/memcg_test.txt b/Documentation/cgroups/memcg_test.txt
index fc8fa97a09ac..ce94a83a7d9a 100644
--- a/Documentation/cgroups/memcg_test.txt
+++ b/Documentation/cgroups/memcg_test.txt
@@ -399,8 +399,7 @@ Under below explanation, we assume CONFIG_MEM_RES_CTRL_SWAP=y.
 
  9.10 Memory thresholds
         Memory controller implements memory thresholds using cgroups notification
-        API. You can use Documentation/cgroups/cgroup_event_listener.c to test
-        it.
+        API. You can use tools/cgroup/cgroup_event_listener.c to test it.
 
         (Shell-A) Create cgroup and run event listener
         # mkdir /cgroup/A