On Wed, Nov 28, 2012 at 02:29:08AM -0800, Anton Vorontsov wrote:
> +static int mpc_pre_destroy(struct cgroup *cg)
> +{
> + struct mpc_state *mpc = cg2mpc(cg);
> + int ret = 0;
> +
> + mutex_lock(&mpc->lock);
> +
> + if (mpc->eventfd)
> + ret = -EBUSY;
cgroup_rmdir() will unregister all events for you. No need to handle it
here.
> +
> + mutex_unlock(&mpc->lock);
> +
> + return ret;
> +}
> +static int mpc_register_level_event(struct cgroup *cg, struct cftype *cft,
> + struct eventfd_ctx *eventfd,
> + const char *args)
> +{
> + struct mpc_state *mpc = cg2mpc(cg);
> + int i;
> + int ret;
> +
> + mutex_lock(&mpc->lock);
> +
> + /*
> + * It's easy to implement multiple thresholds, but so far we don't
> + * need it.
> + */
> + if (mpc->eventfd) {
> + ret = -EBUSY;
> + goto out_unlock;
> + }
One user which listen for one threashold per cgroup?
I think it's wrong. It's essensial for API to serve multiple users.
> +
> + ret = -EINVAL;
> + for (i = 0; i < VMPRESSURE_NUM_LEVELS; i++) {
> + if (strcmp(vmpressure_str_levels[i], args))
> + continue;
> + mpc->eventfd = eventfd;
> + mpc->thres = i;
> + ret = 0;
> + break;
> + }
> +out_unlock:
> + mutex_unlock(&mpc->lock);
> +
> + return ret;
> +}
--
Kirill A. Shutemov
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