On Tue, Jul 25, 2023 at 08:39:17AM -0400, Michael S. Tsirkin wrote:
On Tue, Jul 25, 2023 at 02:28:02PM +0200, Stefano Garzarella wrote:On Tue, Jul 25, 2023 at 12:16:11PM +0300, Arseniy Krasnov wrote: > > > On 25.07.2023 11:46, Arseniy Krasnov wrote: > > > > > > On 25.07.2023 11:43, Stefano Garzarella wrote: > > > On Fri, Jul 21, 2023 at 08:09:03AM +0300, Arseniy Krasnov wrote: > > > > > > > > > > > > On 21.07.2023 00:42, Arseniy Krasnov wrote: > > > > > This adds handling of MSG_ZEROCOPY flag on transmission path: if this > > > > > flag is set and zerocopy transmission is possible (enabled in socket > > > > > options and transport allows zerocopy), then non-linear skb will be > > > > > created and filled with the pages of user's buffer. Pages of user's > > > > > buffer are locked in memory by 'get_user_pages()'. Second thing that > > > > > this patch does is replace type of skb owning: instead of calling > > > > > 'skb_set_owner_sk_safe()' it calls 'skb_set_owner_w()'. Reason of this > > > > > change is that '__zerocopy_sg_from_iter()' increments 'sk_wmem_alloc' > > > > > of socket, so to decrease this field correctly proper skb destructor is > > > > > needed: 'sock_wfree()'. This destructor is set by 'skb_set_owner_w()'. > > > > > > > > > > Signed-off-by: Arseniy Krasnov <AVKrasnov@xxxxxxxxxxxxxx> > > > > > --- > > > > > Changelog: > > > > > v5(big patchset) -> v1: > > > > > * Refactorings of 'if' conditions. > > > > > * Remove extra blank line. > > > > > * Remove 'frag_off' field unneeded init. > > > > > * Add function 'virtio_transport_fill_skb()' which fills both linear > > > > > and non-linear skb with provided data. > > > > > v1 -> v2: > > > > > * Use original order of last four arguments in 'virtio_transport_alloc_skb()'. > > > > > v2 -> v3: > > > > > * Add new transport callback: 'msgzerocopy_check_iov'. It checks that > > > > > provided 'iov_iter' with data could be sent in a zerocopy mode. > > > > > If this callback is not set in transport - transport allows to send > > > > > any 'iov_iter' in zerocopy mode. Otherwise - if callback returns 'true' > > > > > then zerocopy is allowed. Reason of this callback is that in case of > > > > > G2H transmission we insert whole skb to the tx virtio queue and such > > > > > skb must fit to the size of the virtio queue to be sent in a single > > > > > iteration (may be tx logic in 'virtio_transport.c' could be reworked > > > > > as in vhost to support partial send of current skb). This callback > > > > > will be enabled only for G2H path. For details pls see comment > > > > > 'Check that tx queue...' below. > > > > > > > > > > include/net/af_vsock.h | 3 + > > > > > net/vmw_vsock/virtio_transport.c | 39 ++++ > > > > > net/vmw_vsock/virtio_transport_common.c | 257 ++++++++++++++++++------ > > > > > 3 files changed, 241 insertions(+), 58 deletions(-) > > > > > > > > > > diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h > > > > > index 0e7504a42925..a6b346eeeb8e 100644 > > > > > --- a/include/net/af_vsock.h > > > > > +++ b/include/net/af_vsock.h > > > > > @@ -177,6 +177,9 @@ struct vsock_transport { > > > > > > > > > > /* Read a single skb */ > > > > > int (*read_skb)(struct vsock_sock *, skb_read_actor_t); > > > > > + > > > > > + /* Zero-copy. */ > > > > > + bool (*msgzerocopy_check_iov)(const struct iov_iter *); > > > > > }; > > > > > > > > > > /**** CORE ****/ > > > > > diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c > > > > > index 7bbcc8093e51..23cb8ed638c4 100644 > > > > > --- a/net/vmw_vsock/virtio_transport.c > > > > > +++ b/net/vmw_vsock/virtio_transport.c > > > > > @@ -442,6 +442,43 @@ static void virtio_vsock_rx_done(struct virtqueue *vq) > > > > > queue_work(virtio_vsock_workqueue, &vsock->rx_work); > > > > > } > > > > > > > > > > +static bool > > > > > virtio_transport_msgzerocopy_check_iov(const struct > > > > > iov_iter *iov) > > > > > +{ > > > > > + struct virtio_vsock *vsock; > > > > > + bool res = false; > > > > > + > > > > > + rcu_read_lock(); > > > > > + > > > > > + vsock = rcu_dereference(the_virtio_vsock); > > > > > + if (vsock) { Just noted, what about the following to reduce the indentation? if (!vsock) { goto out; }no {} pls
ooops, true, too much QEMU code today, but luckily checkpatch would have spotted it ;-)
... ... out: rcu_read_unlock(); return res;indentation is quite modest here. Not sure goto is worth it.
It's a pattern we follow a lot in this file, and I find the early return/goto more readable. Anyway, I don't have a strong opinion, it's fine the way it is now, actually we don't have too many indentations for now in this function. Thanks, Stefano _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
