From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: virtio-dev-return-5241-cohuck=redhat.com@lists.oasis-open.org Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 169D7985C1A for ; Thu, 3 Jan 2019 16:28:34 +0000 (UTC) Date: Thu, 3 Jan 2019 11:28:28 -0500 From: "Michael S. Tsirkin" Message-ID: <20190103112627-mutt-send-email-mst@kernel.org> References: <20190103160804.21438-1-cohuck@redhat.com> <20190103160804.21438-3-cohuck@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190103160804.21438-3-cohuck@redhat.com> Subject: [virtio-dev] Re: [PATCH 2/2] virtio: document virtio_config_ops restrictions To: Cornelia Huck Cc: Jason Wang , virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, virtio-dev@lists.oasis-open.org, Wei Wang , Halil Pasic List-ID: On Thu, Jan 03, 2019 at 05:08:04PM +0100, Cornelia Huck wrote: > Some transports (e.g. virtio-ccw) implement virtio operations that > seem to be a simple read/write as something more involved that > cannot be done from an atomic context. > > Give at least a hint about that. > > Signed-off-by: Cornelia Huck > --- > include/linux/virtio_config.h | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h > index 7087ef946ba7..987b6491b946 100644 > --- a/include/linux/virtio_config.h > +++ b/include/linux/virtio_config.h > @@ -12,6 +12,11 @@ struct irq_affinity; > > /** > * virtio_config_ops - operations for configuring a virtio device > + * Note: Do not assume that a transport implements all of the operations > + * getting/setting a value as a simple read/write! Generally speaking, > + * any of @get/@set, @get_status/@set_status, or @get_features/ > + * @finalize_features are NOT safe to be called from an atomic > + * context. > * @get: read the value of a configuration field > * vdev: the virtio_device > * offset: the offset of the configuration field Then might_sleep in virtio_cread/virtio_cwrite and friends would be appropriate? I guess we'll need to fix balloon first. > -- > 2.17.2 --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org