On Feb 7, 2008 7:37 AM, Pavel Emelyanov <xemul@xxxxxxxxxx> wrote:
> The Documentation/cgroups.txt file contains the info on how
> to write some controller for cgroups subsystem, but even with
> this, one need to write quite a lot of code before developing
> the core (or copy-n-paste it from some other place).
Good idea.
> +
> +static ssize_t foo_bar_read(struct cgroup *cg, struct cftype *cft,
> + struct file *file, char __user *userbuf,
> + size_t nbytes, loff_t *ppos)
> +{
> + struct foo_cgroup *foo;
> +
> + foo = foo_from_cgroup(cg);
> +
> + /*
> + * produce some output
> + */
> +
> + return nbytes;
> +}
> +
> +static ssize_t foo_bar_write(struct cgroup *cg, struct cftype *cft,
> + struct file *file, const char __user *userbuf,
> + size_t nbytes, loff_t *ppos)
> +{
> + struct foo_cgroup *foo;
> +
> + foo = foo_from_cgroup(cg);
> +
> + /*
> + * read and tune the foo
> + */
> +
> + return nbytes;
> +}
> +
> +static struct cftype foo_files[] = {
> + {
> + .name = "bar",
> + .read = foo_bar_read,
> + .write = foo_bar_write,
> + },
> +};
Can you structure this example so as to encourage people to use the
more formatted read/write routines, such as read_int64 and
write_int64?
> +
> +static struct cgroup_subsys_state *foo_create(struct cgroup_subsys *cs,
> + struct cgroup *cg)
> +{
> + struct foo_cgroup *foo;
> +
Maybe add a comment here that mentions that if your cgroup needs very
early initialization, you can check for cg->parent being NULL, and
return a statically-constructed structure here. (And set
foo_subsys.early_init = 1)
Paul
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