On Wed, 19 Aug 2009 01:31:29 am Amit Shah wrote:
> This helper returns 1 if a call to add_buf will not fail
> with -ENOSPC.
>
> This will help callers that do
>
> while(1) {
> alloc()
> if (add_buf()) {
> free();
> break;
> }
> }
>
> This will result in one less alloc/free exercise.
Hi Amit,
This is what I have in my tree; similar motivation. I didn't
adapt virtio_net like you did tho.
virtio: make add_buf return capacity remaining
This API change means that virtio_net can tell how much capacity
remains for buffers. It's necessarily fuzzy, since
VIRTIO_RING_F_INDIRECT_DESC means we can fit any number of descriptors
in one, *if* we can kmalloc.
Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Dinesh Subhraveti <dineshs@xxxxxxxxxx>
---
drivers/block/virtio_blk.c | 2 +-
drivers/char/hw_random/virtio-rng.c | 2 +-
drivers/char/virtio_console.c | 4 ++--
drivers/net/virtio_net.c | 8 ++++----
drivers/virtio/virtio_balloon.c | 2 +-
drivers/virtio/virtio_ring.c | 6 +++++-
include/linux/virtio.h | 2 +-
net/9p/trans_virtio.c | 2 +-
8 files changed, 16 insertions(+), 12 deletions(-)
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -139,7 +139,7 @@ static bool do_req(struct request_queue
}
}
- if (vblk->vq->vq_ops->add_buf(vblk->vq, vblk->sg, out, in, vbr)) {
+ if (vblk->vq->vq_ops->add_buf(vblk->vq, vblk->sg, out, in, vbr) < 0) {
mempool_free(vbr, vblk->pool);
return false;
}
diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c
--- a/drivers/char/hw_random/virtio-rng.c
+++ b/drivers/char/hw_random/virtio-rng.c
@@ -51,7 +51,7 @@ static void register_buffer(void)
sg_init_one(&sg, random_data+data_left, RANDOM_DATA_SIZE-data_left);
/* There should always be room for one buffer. */
- if (vq->vq_ops->add_buf(vq, &sg, 0, 1, random_data) != 0)
+ if (vq->vq_ops->add_buf(vq, &sg, 0, 1, random_data) < 0)
BUG();
vq->vq_ops->kick(vq);
}
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -65,7 +65,7 @@ static int put_chars(u32 vtermno, const
/* add_buf wants a token to identify this buffer: we hand it any
* non-NULL pointer, since there's only ever one buffer. */
- if (out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, (void *)1) == 0) {
+ if (out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, (void *)1) >= 0) {
/* Tell Host to go! */
out_vq->vq_ops->kick(out_vq);
/* Chill out until it's done with the buffer. */
@@ -85,7 +85,7 @@ static void add_inbuf(void)
sg_init_one(sg, inbuf, PAGE_SIZE);
/* We should always be able to add one buffer to an empty queue. */
- if (in_vq->vq_ops->add_buf(in_vq, sg, 0, 1, inbuf) != 0)
+ if (in_vq->vq_ops->add_buf(in_vq, sg, 0, 1, inbuf) < 0)
BUG();
in_vq->vq_ops->kick(in_vq);
}
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -300,7 +300,7 @@ static void try_fill_recv_maxbufs(struct
skb_queue_head(&vi->recv, skb);
err = vi->rvq->vq_ops->add_buf(vi->rvq, sg, 0, num, skb);
- if (err) {
+ if (err < 0) {
skb_unlink(skb, &vi->recv);
trim_pages(vi, skb);
kfree_skb(skb);
@@ -349,7 +349,7 @@ static void try_fill_recv(struct virtnet
skb_queue_head(&vi->recv, skb);
err = vi->rvq->vq_ops->add_buf(vi->rvq, sg, 0, 1, skb);
- if (err) {
+ if (err < 0) {
skb_unlink(skb, &vi->recv);
kfree_skb(skb);
break;
@@ -480,7 +480,7 @@ again:
/* Put new one in send queue and do transmit */
__skb_queue_head(&vi->send, skb);
- if (likely(xmit_skb(vi, skb) == 0)) {
+ if (likely(xmit_skb(vi, skb) >= 0)) {
vi->svq->vq_ops->kick(vi->svq);
/* Don't wait up for transmitted skbs to be freed. */
skb_orphan(skb);
@@ -577,7 +577,7 @@ static bool virtnet_send_command(struct
sg_set_buf(&sg[i + 1], sg_virt(s), s->length);
sg_set_buf(&sg[out + in - 1], &status, sizeof(status));
- BUG_ON(vi->cvq->vq_ops->add_buf(vi->cvq, sg, out, in, vi));
+ BUG_ON(vi->cvq->vq_ops->add_buf(vi->cvq, sg, out, in, vi) < 0);
vi->cvq->vq_ops->kick(vi->cvq);
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -84,7 +84,7 @@ static void tell_host(struct virtio_ball
init_completion(&vb->acked);
/* We should always be able to add one buffer to an empty queue. */
- if (vq->vq_ops->add_buf(vq, &sg, 1, 0, vb) != 0)
+ if (vq->vq_ops->add_buf(vq, &sg, 1, 0, vb) < 0)
BUG();
vq->vq_ops->kick(vq);
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -213,7 +213,11 @@ add_head:
pr_debug("Added buffer head %i to %p\n", head, vq);
END_USE(vq);
- return 0;
+
+ /* If we're indirect, we can fit many (assuming not OOM). */
+ if (vq->indirect)
+ return vq->num_free ? vq->vring.num : 0;
+ return vq->num_free;
}
static void vring_kick(struct virtqueue *_vq)
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -34,7 +34,7 @@ struct virtqueue {
* out_num: the number of sg readable by other side
* in_num: the number of sg which are writable (after readable ones)
* data: the token identifying the buffer.
- * Returns 0 or an error.
+ * Returns remaining capacity of queue (sg segments) or a negative error.
* @kick: update after add_buf
* vq: the struct virtqueue
* After one or more add_buf calls, invoke this to kick the other side.
diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
--- a/net/9p/trans_virtio.c
+++ b/net/9p/trans_virtio.c
@@ -203,7 +203,7 @@ p9_virtio_request(struct p9_client *clie
req->status = REQ_STATUS_SENT;
- if (chan->vq->vq_ops->add_buf(chan->vq, chan->sg, out, in, req->tc)) {
+ if (chan->vq->vq_ops->add_buf(chan->vq, chan->sg, out, in, req->tc) < 0) {
P9_DPRINTK(P9_DEBUG_TRANS,
"9p debug: virtio rpc add_buf returned failure");
return -EIO;
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