Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1670968 > unrolled thread

Re: [PATCH v4 13/18] xen/pvcalls: implement release command

Back to article view | Back to linux.kernel

This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by below is the oldest one visible, not the original post.

Contents

  Re: [PATCH v4 13/18] xen/pvcalls: implement release command Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-06-20 19:20 +0200
    Re: [PATCH v4 13/18] xen/pvcalls: implement release command Stefano Stabellini <sstabellini@kernel.org> - 2017-06-21 23:40 +0200

#1670968 — Re: [PATCH v4 13/18] xen/pvcalls: implement release command

> +
> +static int pvcalls_back_release_passive(struct xenbus_device *dev,
> +					struct pvcalls_fedata *fedata,
> +					struct sockpass_mapping *mappass)
> +{
> +	if (mappass->sock->sk != NULL) {
> +		write_lock_bh(&mappass->sock->sk->sk_callback_lock);
> +		mappass->sock->sk->sk_user_data = NULL;
> +		mappass->sock->sk->sk_data_ready = mappass->saved_data_ready;
> +		write_unlock_bh(&mappass->sock->sk->sk_callback_lock);
> +	}
> +	down(&fedata->socket_lock);
> +	radix_tree_delete(&fedata->socketpass_mappings, mappass->id);
> +	sock_release(mappass->sock);
> +	flush_workqueue(mappass->wq);
> +	destroy_workqueue(mappass->wq);
> +	kfree(mappass);
> +	up(&fedata->socket_lock);

Can you raise the semaphore earlier, once the mapping is deleted from
the tree?

Also, why are you not locking the tree in pvcalls_back_accept()?

-boris

[toc] | [next] | [standalone]

#1672080

On Tue, 20 Jun 2017, Boris Ostrovsky wrote:
> > +
> > +static int pvcalls_back_release_passive(struct xenbus_device *dev,
> > +					struct pvcalls_fedata *fedata,
> > +					struct sockpass_mapping *mappass)
> > +{
> > +	if (mappass->sock->sk != NULL) {
> > +		write_lock_bh(&mappass->sock->sk->sk_callback_lock);
> > +		mappass->sock->sk->sk_user_data = NULL;
> > +		mappass->sock->sk->sk_data_ready = mappass->saved_data_ready;
> > +		write_unlock_bh(&mappass->sock->sk->sk_callback_lock);
> > +	}
> > +	down(&fedata->socket_lock);
> > +	radix_tree_delete(&fedata->socketpass_mappings, mappass->id);
> > +	sock_release(mappass->sock);
> > +	flush_workqueue(mappass->wq);
> > +	destroy_workqueue(mappass->wq);
> > +	kfree(mappass);
> > +	up(&fedata->socket_lock);
> 
> Can you raise the semaphore earlier, once the mapping is deleted from
> the tree?

Yes, I think it can.

> Also, why are you not locking the tree in pvcalls_back_accept()?

Good point! Although socket_lock is used to protect insertions and
deletions to socketpass_mappings and socket_mappings, many of the sites
that only access socket_mappings and socketpass_mappings without making
modifications are left unprotected at the moment. I'll fix that, and to
do it I'll move radix_tree_delete out of pvcalls_back_release_passive.

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web