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Date: Thu, 24 Apr 2014 00:45:58 +0300
From: Dan Carpenter <dan.carpenter@...cle.com>
To: "K. Y. Srinivasan" <kys@...rosoft.com>
Cc: davem@...emloft.net, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org, devel@...uxdriverproject.org,
olaf@...fle.de, apw@...onical.com, jasowang@...hat.com
Subject: Re: [PATCH V1 net-next 1/1] hyperv: Enable sendbuf mechanism on the
send path
TLDR; Style nits and we should return -ENOMEM on error instead of
success.
On Wed, Apr 23, 2014 at 02:24:45PM -0700, K. Y. Srinivasan wrote:
> We send packets using a copy-free mechanism (this is the Guest to Host transport
> via VMBUS). While this is obviously optimal for large packets,
> it may not be optimal for small packets. Hyper-V host supports
> a second mechanism for sending packets that is "copy based". We implement that
> mechanism in this patch.
>
> In this version of the patch I have addressed a comment from David Miller.
>
> With this patch (and all of the other offload and VRSS patches), we are now able
> to almost saturate a 10G interface between Linux VMs on Hyper-V
> on different hosts - close to 9 Gbps as measured via iperf.
>
> Signed-off-by: K. Y. Srinivasan <kys@...rosoft.com>
> Reviewed-by: Haiyang Zhang <haiyangz@...rosoft.com>
> ---
> drivers/net/hyperv/hyperv_net.h | 14 +++
> drivers/net/hyperv/netvsc.c | 226 +++++++++++++++++++++++++++++++++++++--
> drivers/net/hyperv/netvsc_drv.c | 3 +-
> 3 files changed, 234 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
> index d1f7826..4b7df5a 100644
> --- a/drivers/net/hyperv/hyperv_net.h
> +++ b/drivers/net/hyperv/hyperv_net.h
> @@ -140,6 +140,8 @@ struct hv_netvsc_packet {
> void *send_completion_ctx;
> void (*send_completion)(void *context);
>
> + u32 send_buf_index;
> +
> /* This points to the memory after page_buf */
> struct rndis_message *rndis_msg;
>
> @@ -582,6 +584,9 @@ struct nvsp_message {
>
> #define NETVSC_RECEIVE_BUFFER_SIZE (1024*1024*16) /* 16MB */
> #define NETVSC_RECEIVE_BUFFER_SIZE_LEGACY (1024*1024*15) /* 15MB */
> +#define NETVSC_SEND_BUFFER_SIZE (1024 * 1024) /* 1MB */
> +#define NETVSC_INVALID_INDEX -1
> +
>
> #define NETVSC_RECEIVE_BUFFER_ID 0xcafe
>
> @@ -607,6 +612,15 @@ struct netvsc_device {
> u32 recv_section_cnt;
> struct nvsp_1_receive_buffer_section *recv_section;
>
> + /* Send buffer allocated by us */
> + void *send_buf;
> + u32 send_buf_size;
> + u32 send_buf_gpadl_handle;
> + u32 send_section_cnt;
> + u32 send_section_size;
> + unsigned long *send_section_map;
> + int map_words;
> +
> /* Used for NetVSP initialization protocol */
> struct completion channel_init_wait;
> struct nvsp_message channel_init_pkt;
> diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
> index bbee446..c041f63 100644
> --- a/drivers/net/hyperv/netvsc.c
> +++ b/drivers/net/hyperv/netvsc.c
> @@ -28,6 +28,7 @@
> #include <linux/slab.h>
> #include <linux/netdevice.h>
> #include <linux/if_ether.h>
> +#include <asm/sync_bitops.h>
>
> #include "hyperv_net.h"
>
> @@ -80,7 +81,7 @@ get_in_err:
> }
>
>
> -static int netvsc_destroy_recv_buf(struct netvsc_device *net_device)
> +static int netvsc_destroy_buf(struct netvsc_device *net_device)
> {
> struct nvsp_message *revoke_packet;
> int ret = 0;
> @@ -146,10 +147,62 @@ static int netvsc_destroy_recv_buf(struct netvsc_device *net_device)
> net_device->recv_section = NULL;
> }
>
> + /* Deal with the send buffer we may have setup.
> + * If we got a send section size, it means we received a
> + * SendsendBufferComplete msg (ie sent
> + * NvspMessage1TypeSendReceiveBuffer msg) therefore, we need
> + * to send a revoke msg here
> + */
> + if (net_device->send_section_size) {
> + /* Send the revoke receive buffer */
> + revoke_packet = &net_device->revoke_packet;
> + memset(revoke_packet, 0, sizeof(struct nvsp_message));
> +
> + revoke_packet->hdr.msg_type =
> + NVSP_MSG1_TYPE_REVOKE_SEND_BUF;
This fits in 80 characters.
revoke_packet->hdr.msg_type = NVSP_MSG1_TYPE_REVOKE_SEND_BUF;
> + revoke_packet->msg.v1_msg.revoke_recv_buf.id = 0;
> +
> + ret = vmbus_sendpacket(net_device->dev->channel,
> + revoke_packet,
> + sizeof(struct nvsp_message),
> + (unsigned long)revoke_packet,
> + VM_PKT_DATA_INBAND, 0);
> + /* If we failed here, we might as well return and
> + * have a leak rather than continue and a bugchk
> + */
> + if (ret != 0) {
I have never been a big fan of these double negative conditions. It's
simpler and more normal style to say: "if (ret) { ". There are some
cases where it makes sense to compare against zero. For example, if you
are dealing with a variable as a number then you would say
"if (x == 0) ... else if (x == 1) ". Also for strcmp() then you should
use == 0 and != 0. But for error codes it's better it's more idiomatic
to just say "if (ret) ".
> + netdev_err(ndev, "unable to send "
> + "revoke send buffer to netvsp\n");
> + return ret;
> + }
> + }
> + /* Teardown the gpadl on the vsp end */
> + if (net_device->send_buf_gpadl_handle) {
> + ret = vmbus_teardown_gpadl(net_device->dev->channel,
> + net_device->send_buf_gpadl_handle);
> +
> + /* If we failed here, we might as well return and have a leak
> + * rather than continue and a bugchk
> + */
> + if (ret != 0) {
> + netdev_err(ndev,
> + "unable to teardown send buffer's gpadl\n");
> + return ret;
> + }
> + net_device->recv_buf_gpadl_handle = 0;
> + }
> + if (net_device->send_buf) {
> + /* Free up the receive buffer */
> + free_pages((unsigned long)net_device->send_buf,
> + get_order(net_device->send_buf_size));
> + net_device->send_buf = NULL;
> + }
> + kfree(net_device->send_section_map);
> +
> return ret;
This patch doesn't introduce this, but it's better to say:
return 0;
That is more clear so you don't have to back trace and verify what
"ret" is.
> }
>
> -static int netvsc_init_recv_buf(struct hv_device *device)
> +static int netvsc_init_buf(struct hv_device *device)
> {
> int ret = 0;
> int t;
> @@ -248,10 +301,90 @@ static int netvsc_init_recv_buf(struct hv_device *device)
> goto cleanup;
> }
>
> + /* Now setup the send buffer.
> + */
> + net_device->send_buf =
> + (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO,
> + get_order(net_device->send_buf_size));
> + if (!net_device->send_buf) {
> + netdev_err(ndev, "unable to allocate send "
> + "buffer of size %d\n", net_device->send_buf_size);
This string actually fits into 80 characters fine as-is.
netdev_err(ndev, "unable to allocate send buffer of size %d\n",
net_device->send_buf_size);
> + ret = -ENOMEM;
> + goto cleanup;
> + }
> +
> + /* Establish the gpadl handle for this buffer on this
> + * channel. Note: This call uses the vmbus connection rather
> + * than the channel to establish the gpadl handle.
> + */
> + ret = vmbus_establish_gpadl(device->channel, net_device->send_buf,
> + net_device->send_buf_size,
> + &net_device->send_buf_gpadl_handle);
> + if (ret != 0) {
> + netdev_err(ndev,
> + "unable to establish send buffer's gpadl\n");
Same. Just put it on one line.
netdev_err(ndev, "unable to establish send buffer's gpadl\n");
> + goto cleanup;
> + }
> +
> + /* Notify the NetVsp of the gpadl handle */
> + init_packet = &net_device->channel_init_pkt;
> + memset(init_packet, 0, sizeof(struct nvsp_message));
> + init_packet->hdr.msg_type = NVSP_MSG1_TYPE_SEND_SEND_BUF;
> + init_packet->msg.v1_msg.send_recv_buf.gpadl_handle =
> + net_device->send_buf_gpadl_handle;
> + init_packet->msg.v1_msg.send_recv_buf.id = 0;
> +
> + /* Send the gpadl notification request */
> + ret = vmbus_sendpacket(device->channel, init_packet,
> + sizeof(struct nvsp_message),
> + (unsigned long)init_packet,
> + VM_PKT_DATA_INBAND,
> + VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
> + if (ret != 0) {
> + netdev_err(ndev,
> + "unable to send send buffer's gpadl to netvsp\n");
> + goto cleanup;
> + }
> +
> + t = wait_for_completion_timeout(&net_device->channel_init_wait, 5*HZ);
> + BUG_ON(t == 0);
Is there no way to just return an error code here? We may as well use
wait_for_completion() without the timeout if we're just going to call
BUG_ON() anyway.
> +
> + /* Check the response */
> + if (init_packet->msg.v1_msg.
> + send_send_buf_complete.status != NVSP_STAT_SUCCESS) {
Better to break it up like this:
if (init_packet->msg.v1_msg.send_send_buf_complete.status !=
NVSP_STAT_SUCCESS) {
There has to be a better name for "send_send_buf_complete"...
> + netdev_err(ndev, "Unable to complete send buffer "
> + "initialization with NetVsp - status %d\n",
> + init_packet->msg.v1_msg.
> + send_recv_buf_complete.status);
> + ret = -EINVAL;
> + goto cleanup;
> + }
> +
> + /* Parse the response */
> + net_device->send_section_size = init_packet->msg.
> + v1_msg.send_send_buf_complete.section_size;
> +
> + /* Section count is simply the size divided by the section size.
> + */
> + net_device->send_section_cnt =
> + net_device->send_buf_size/net_device->send_section_size;
> +
> + dev_info(&device->device, "Send section size: %d, Section count:%d\n",
> + net_device->send_section_size, net_device->send_section_cnt);
> +
> + /* Setup state for managing the send buffer. */
> + net_device->map_words = DIV_ROUND_UP(net_device->send_section_cnt,
> + BITS_PER_LONG);
> +
> + net_device->send_section_map =
> + kzalloc(net_device->map_words * sizeof(ulong), GFP_KERNEL);
Use kcalloc().
net_device->send_section_map = kcalloc(net_device->map_words,
sizeof(ulong), GFP_KERNEL);
> + if (net_device->send_section_map == NULL)
> + goto cleanup;
Set "ret = -ENOMEM;"
> +
> goto exit;
>
These bunny hops are super annoying. Just return success here. Why
does code have to be all tangled up?
> cleanup:
> - netvsc_destroy_recv_buf(net_device);
> + netvsc_destroy_buf(net_device);
>
> exit:
> return ret;
> @@ -369,8 +502,9 @@ static int netvsc_connect_vsp(struct hv_device *device)
> net_device->recv_buf_size = NETVSC_RECEIVE_BUFFER_SIZE_LEGACY;
> else
> net_device->recv_buf_size = NETVSC_RECEIVE_BUFFER_SIZE;
> + net_device->send_buf_size = NETVSC_SEND_BUFFER_SIZE;
>
> - ret = netvsc_init_recv_buf(device);
> + ret = netvsc_init_buf(device);
>
> cleanup:
> return ret;
> @@ -378,7 +512,7 @@ cleanup:
>
> static void netvsc_disconnect_vsp(struct netvsc_device *net_device)
> {
> - netvsc_destroy_recv_buf(net_device);
> + netvsc_destroy_buf(net_device);
> }
>
> /*
> @@ -440,6 +574,12 @@ static inline u32 hv_ringbuf_avail_percent(
> return avail_write * 100 / ring_info->ring_datasize;
> }
>
> +static inline void netvsc_free_send_slot(struct netvsc_device *net_device,
> + u32 index)
> +{
> + sync_change_bit(index, net_device->send_section_map);
> +}
> +
> static void netvsc_send_completion(struct netvsc_device *net_device,
> struct hv_device *device,
> struct vmpacket_descriptor *packet)
> @@ -447,6 +587,7 @@ static void netvsc_send_completion(struct netvsc_device *net_device,
> struct nvsp_message *nvsp_packet;
> struct hv_netvsc_packet *nvsc_packet;
> struct net_device *ndev;
> + u32 send_index;
>
> ndev = net_device->ndev;
>
> @@ -477,6 +618,9 @@ static void netvsc_send_completion(struct netvsc_device *net_device,
>
> /* Notify the layer above us */
> if (nvsc_packet) {
> + send_index = nvsc_packet->send_buf_index;
> + if (send_index != NETVSC_INVALID_INDEX)
> + netvsc_free_send_slot(net_device, send_index);
> q_idx = nvsc_packet->q_idx;
> channel = nvsc_packet->channel;
> nvsc_packet->send_completion(nvsc_packet->
> @@ -504,6 +648,52 @@ static void netvsc_send_completion(struct netvsc_device *net_device,
>
> }
>
> +static u32 netvsc_get_next_send_section(struct netvsc_device *net_device)
> +{
> + unsigned long index;
> + u32 max_words = net_device->map_words;
> + unsigned long *map_addr = (unsigned long *)net_device->send_section_map;
> + u32 section_cnt = net_device->send_section_cnt;
> + int ret_val = NETVSC_INVALID_INDEX;
> + int i;
> + int prev_val;
> +
> + for (i = 0; i < max_words; i++) {
> + if (!~(map_addr[i]))
> + continue;
> + index = ffz(map_addr[i]);
> + prev_val = sync_test_and_set_bit(index, &map_addr[i]);
> + if (prev_val)
> + continue;
> + if ((index + (i * BITS_PER_LONG)) >= section_cnt)
> + break;
> + ret_val = (index + (i * BITS_PER_LONG));
> + break;
> + }
> + return ret_val;
> +}
> +
> +u32 netvsc_copy_to_send_buf(struct netvsc_device *net_device,
> + unsigned int section_index,
> + struct hv_netvsc_packet *packet)
> +{
> + char *start = net_device->send_buf;
> + char *dest = (start + (section_index * net_device->send_section_size));
> + int i;
> + u32 msg_size = 0;
> +
> + for (i = 0; i < packet->page_buf_cnt; i++) {
> + char *src = phys_to_virt(packet->page_buf[i].pfn << PAGE_SHIFT);
> + u32 offset = packet->page_buf[i].offset;
> + u32 len = packet->page_buf[i].len;
> +
> + memcpy(dest, (src + offset), len);
> + msg_size += len;
> + dest += len;
> + }
> + return msg_size;
> +}
> +
> int netvsc_send(struct hv_device *device,
> struct hv_netvsc_packet *packet)
> {
> @@ -513,6 +703,10 @@ int netvsc_send(struct hv_device *device,
> struct net_device *ndev;
> struct vmbus_channel *out_channel = NULL;
> u64 req_id;
> + unsigned int section_index = NETVSC_INVALID_INDEX;
> + u32 msg_size = 0;
> + struct sk_buff *skb;
> +
>
Don't put consecutive blank lines.
> net_device = get_outbound_net_device(device);
> if (!net_device)
> @@ -528,10 +722,26 @@ int netvsc_send(struct hv_device *device,
> sendMessage.msg.v1_msg.send_rndis_pkt.channel_type = 1;
> }
>
> - /* Not using send buffer section */
> + /* Attempt to send via sendbuf */
> + if (packet->total_data_buflen < net_device->send_section_size) {
> + section_index = netvsc_get_next_send_section(net_device);
> + if (section_index != NETVSC_INVALID_INDEX) {
> + msg_size = netvsc_copy_to_send_buf(net_device,
> + section_index,
> + packet);
> + skb = (struct sk_buff *)
> + (unsigned long)packet->send_completion_tid;
> + if (skb)
> + dev_kfree_skb_any(skb);
> + packet->page_buf_cnt = 0;
> + }
> + }
> + packet->send_buf_index = section_index;
> +
> +
Don't put consective blank lines.
regards,
dan carpenter
> sendMessage.msg.v1_msg.send_rndis_pkt.send_buf_section_index =
> - 0xFFFFFFFF;
> - sendMessage.msg.v1_msg.send_rndis_pkt.send_buf_section_size = 0;
> + section_index;
> + sendMessage.msg.v1_msg.send_rndis_pkt.send_buf_section_size = msg_size;
>
> if (packet->send_completion)
> req_id = (ulong)packet;
> diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
> index c76b665..939e3af 100644
> --- a/drivers/net/hyperv/netvsc_drv.c
> +++ b/drivers/net/hyperv/netvsc_drv.c
> @@ -236,10 +236,11 @@ static void netvsc_xmit_completion(void *context)
> struct hv_netvsc_packet *packet = (struct hv_netvsc_packet *)context;
> struct sk_buff *skb = (struct sk_buff *)
> (unsigned long)packet->send_completion_tid;
> + u32 index = packet->send_buf_index;
>
> kfree(packet);
>
> - if (skb)
> + if (skb && (index == NETVSC_INVALID_INDEX))
> dev_kfree_skb_any(skb);
> }
>
> --
> 1.7.4.1
>
> _______________________________________________
> devel mailing list
> devel@...uxdriverproject.org
> http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
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