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authorGreg Thelen <gthelen@google.com>2013-01-04 13:05:17 -0800
committerTejun Heo <tj@kernel.org>2013-01-07 09:41:28 -0800
commit92e015b1cfc24e3cb072385f25171b8599cc7ef3 (patch)
tree465c64f5b337dcdec22adb6cb4aa82c5fe410bca /tools/cgroup
parent12a9d2fef1d35770d3cdc2cd1faabb83c45bc0fa (diff)
downloadkernel-92e015b1cfc24e3cb072385f25171b8599cc7ef3.tar.gz
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>
Diffstat (limited to 'tools/cgroup')
-rw-r--r--tools/cgroup/.gitignore1
-rw-r--r--tools/cgroup/Makefile11
-rw-r--r--tools/cgroup/cgroup_event_listener.c110
3 files changed, 122 insertions, 0 deletions
diff --git a/tools/cgroup/.gitignore b/tools/cgroup/.gitignore
new file mode 100644
index 000000000000..633cd9b874f9
--- /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 000000000000..b4286196b763
--- /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 000000000000..3e082f96dc12
--- /dev/null
+++ b/tools/cgroup/cgroup_event_listener.c
@@ -0,0 +1,110 @@
+/*
+ * 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);
+}