[PATCH net-next 1/8] skb: report completion status for zero copy skbs
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2012-10-29 15:49:37
Subsystem:
networking [general], the rest, virtio host (vhost) · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds, "Michael S. Tsirkin", Jason Wang
Even if skb is marked for zero copy, net core might still decide to copy it later which is somewhat slower than a copy in user context: besides copying the data we need to pin/unpin the pages. Add a parameter reporting such cases through zero copy callback: if this happens a lot, device can take this into account and switch to copying in user context. This patch updates all users but ignores the passed value for now: it will be used by follow-up patches. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- drivers/vhost/vhost.c | 2 +- drivers/vhost/vhost.h | 2 +- include/linux/skbuff.h | 4 +++- net/core/skbuff.c | 4 ++-- 4 files changed, 7 insertions(+), 5 deletions(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 99ac2cb..92308b6 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c@@ -1600,7 +1600,7 @@ void vhost_ubuf_put_and_wait(struct vhost_ubuf_ref *ubufs) kfree(ubufs); } -void vhost_zerocopy_callback(struct ubuf_info *ubuf) +void vhost_zerocopy_callback(struct ubuf_info *ubuf, int zerocopy_status) { struct vhost_ubuf_ref *ubufs = ubuf->ctx; struct vhost_virtqueue *vq = ubufs->vq;
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 1125af3..eb7263c3 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h@@ -191,7 +191,7 @@ bool vhost_enable_notify(struct vhost_dev *, struct vhost_virtqueue *); int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log, unsigned int log_num, u64 len); -void vhost_zerocopy_callback(struct ubuf_info *); +void vhost_zerocopy_callback(struct ubuf_info *, int); int vhost_zerocopy_signal_used(struct vhost_virtqueue *vq); #define vq_err(vq, fmt, ...) do { \
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 6a2c34e..8bac11b 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h@@ -235,11 +235,13 @@ enum { /* * The callback notifies userspace to release buffers when skb DMA is done in * lower device, the skb last reference should be 0 when calling this. + * The zerocopy_status argument is 0 if zero copy transmit occurred, + * 1 on successful data copy; < 0 on out of memory error. * The ctx field is used to track device context. * The desc field is used to track userspace buffer index. */ struct ubuf_info { - void (*callback)(struct ubuf_info *); + void (*callback)(struct ubuf_info *, int zerocopy_status); void *ctx; unsigned long desc; };
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 6e04b1f..eb31f6e 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c@@ -519,7 +519,7 @@ static void skb_release_data(struct sk_buff *skb) uarg = skb_shinfo(skb)->destructor_arg; if (uarg->callback) - uarg->callback(uarg); + uarg->callback(uarg, 0); } if (skb_has_frag_list(skb))
@@ -797,7 +797,7 @@ int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask) for (i = 0; i < num_frags; i++) skb_frag_unref(skb, i); - uarg->callback(uarg); + uarg->callback(uarg, 1); /* skb frags point to kernel buffers */ for (i = num_frags - 1; i >= 0; i--) {
--
MST