[PATCH v2 -mmotm 3/4] cgroups: Add simple listener of cgroup events to documentation

Li Zefan lizf at cn.fujitsu.com
Tue Feb 23 19:30:20 PST 2010


> +	ret = dprintf(event_control, "%d %d %s", efd, cfd, argv[2]);

I found it won't return negative value for invalid input, though
errno is set properly.

try:
# ./cgroup_event_listner /cgroup/cgroup.procs abc

while strace shows write() does return -1:

# strace ./cgroup_event_listner /cgroup/cgroup.procs abc
...
write(6, "7 5 abc"..., 7)               = -1 EINVAL (Invalid argument)

> +	if (ret == -1) {
> +		perror("Cannot write to cgroup.event_control");
> +		goto out;
> +	}


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