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-rw-r--r--tools/cgroup/.gitignore1
-rw-r--r--tools/cgroup/Makefile11
-rw-r--r--tools/cgroup/cgroup_event_listener.c82
3 files changed, 94 insertions, 0 deletions
diff --git a/tools/cgroup/.gitignore b/tools/cgroup/.gitignore
new file mode 100644
index 00000000000..633cd9b874f
--- /dev/null
+++ b/tools/cgroup/.gitignore
@@ -0,0 +1 @@
+cgroup_event_listener
diff --git a/tools/cgroup/Makefile b/tools/cgroup/Makefile
new file mode 100644
index 00000000000..b4286196b76
--- /dev/null
+++ b/tools/cgroup/Makefile
@@ -0,0 +1,11 @@
+# Makefile for cgroup tools
+
+CC = $(CROSS_COMPILE)gcc
+CFLAGS = -Wall -Wextra
+
+all: cgroup_event_listener
+%: %.c
+ $(CC) $(CFLAGS) -o $@ $^
+
+clean:
+ $(RM) cgroup_event_listener
diff --git a/tools/cgroup/cgroup_event_listener.c b/tools/cgroup/cgroup_event_listener.c
new file mode 100644
index 00000000000..4eb5507205c
--- /dev/null
+++ b/tools/cgroup/cgroup_event_listener.c
@@ -0,0 +1,82 @@
+/*
+ * cgroup_event_listener.c - Simple listener of cgroup events
+ *
+ * Copyright (C) Kirill A. Shutemov <kirill@shutemov.name>
+ */
+
+#include <assert.h>
+#include <err.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>"
+
+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)
+ errx(1, "%s", USAGE_STR);
+
+ cfd = open(argv[1], O_RDONLY);
+ if (cfd == -1)
+ err(1, "Cannot open %s", argv[1]);
+
+ ret = snprintf(event_control_path, PATH_MAX, "%s/cgroup.event_control",
+ dirname(argv[1]));
+ if (ret >= PATH_MAX)
+ errx(1, "Path to cgroup.event_control is too long");
+
+ event_control = open(event_control_path, O_WRONLY);
+ if (event_control == -1)
+ err(1, "Cannot open %s", event_control_path);
+
+ efd = eventfd(0, 0);
+ if (efd == -1)
+ err(1, "eventfd() failed");
+
+ ret = snprintf(line, LINE_MAX, "%d %d %s", efd, cfd, argv[2]);
+ if (ret >= LINE_MAX)
+ errx(1, "Arguments string is too long");
+
+ ret = write(event_control, line, strlen(line) + 1);
+ if (ret == -1)
+ err(1, "Cannot write to cgroup.event_control");
+
+ while (1) {
+ uint64_t result;
+
+ ret = read(efd, &result, sizeof(result));
+ if (ret == -1) {
+ if (errno == EINTR)
+ continue;
+ err(1, "Cannot read from eventfd");
+ }
+ assert(ret == sizeof(result));
+
+ ret = access(event_control_path, W_OK);
+ if ((ret == -1) && (errno == ENOENT)) {
+ puts("The cgroup seems to have removed.");
+ break;
+ }
+
+ if (ret == -1)
+ err(1, "cgroup.event_control is not accessible any more");
+
+ printf("%s %s: crossed\n", argv[1], argv[2]);
+ }
+
+ return 0;
+}