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SubjectRe: [RFC v1 08/14] bus1: implement peer management context
On Wed, Oct 26, 2016 at 9:18 PM, David Herrmann <dh.herrmann@gmail.com> wrote:
> + /* initialize constant fields */
> + peer->id = atomic64_inc_return(&peer_ids);
> + peer->flags = 0;
> + peer->cred = get_cred(current_cred());
> + peer->pid_ns = get_pid_ns(task_active_pid_ns(current));
> + peer->user = user;
> + peer->debugdir = NULL;
> + init_waitqueue_head(&peer->waitq);
> + bus1_active_init(&peer->active);
> +
> + /* initialize data section */
> + mutex_init(&peer->data.lock);
> +
> + /* initialize peer-private section */
> + mutex_init(&peer->local.lock);
> +
> + if (!IS_ERR_OR_NULL(bus1_debugdir)) {

How can bus1_debugdir contain an error code? AFACT it is either a
valid dentry or NULL.

> + char idstr[22];
> +
> + snprintf(idstr, sizeof(idstr), "peer-%llx", peer->id);
> +
> + peer->debugdir = debugfs_create_dir(idstr, bus1_debugdir);
> + if (!peer->debugdir) {
> + pr_err("cannot create debugfs dir for peer %llx\n",
> + peer->id);
> + } else if (!IS_ERR_OR_NULL(peer->debugdir)) {
> + bus1_debugfs_create_atomic_x("active", S_IRUGO,
> + peer->debugdir,
> + &peer->active.count);
> + }
> + }
> +
> + bus1_active_activate(&peer->active);

This is a no-nop since bus1_active_init() set ->count to BUS1_ACTIVE_NEW.

> + return peer;
> +}
> +
> +static int bus1_peer_disconnect(struct bus1_peer *peer)
> +{
> + bus1_active_deactivate(&peer->active);
> + bus1_active_drain(&peer->active, &peer->waitq);
> +
> + if (!bus1_active_cleanup(&peer->active, &peer->waitq,
> + NULL, NULL))
> + return -ESHUTDOWN;
> +
> + return 0;
> +}
> +
> +/**
> + * bus1_peer_free() - destroy peer
> + * @peer: peer to destroy, or NULL
> + *
> + * Destroy a peer object that was previously allocated via bus1_peer_new().
> + * This synchronously waits for any outstanding operations on this peer to
> + * finish, then releases all linked resources and deallocates the peer in an
> + * rcu-delayed manner.
> + *
> + * If NULL is passed, this is a no-op.
> + *
> + * Return: NULL is returned.

What about making the function of type void?

> +struct bus1_peer *bus1_peer_free(struct bus1_peer *peer)
> +{
> + if (!peer)
> + return NULL;
> +
> + /* disconnect from environment */
> + bus1_peer_disconnect(peer);
> +
> + /* deinitialize peer-private section */
> + mutex_destroy(&peer->local.lock);
> +
> + /* deinitialize data section */
> + mutex_destroy(&peer->data.lock);
> +
> + /* deinitialize constant fields */
> + debugfs_remove_recursive(peer->debugdir);
> + bus1_active_deinit(&peer->active);
> + peer->user = bus1_user_unref(peer->user);
> + put_pid_ns(peer->pid_ns);
> + put_cred(peer->cred);
> + kfree_rcu(peer, rcu);
> +
> + return NULL;
> +}

--
Thanks,
//richard

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