This is a note to let you know that I've just added the patch titled
hv_netvsc: use skb_get_hash() instead of a homegrown implementation
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
hv_netvsc-use-skb_get_hash-instead-of-a-homegrown-implementation.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 757647e10e55c01fb7a9c4356529442e316a7c72 Mon Sep 17 00:00:00 2001
From: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
Date: Mon, 25 Jan 2016 16:00:41 +0100
Subject: hv_netvsc: use skb_get_hash() instead of a homegrown implementation
From: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
commit 757647e10e55c01fb7a9c4356529442e316a7c72 upstream.
Recent changes to 'struct flow_keys' (e.g commit d34af823ff40 ("net: Add
VLAN ID to flow_keys")) introduced a performance regression in netvsc
driver. Is problem is, however, not the above mentioned commit but the
fact that netvsc_set_hash() function did some assumptions on the struct
flow_keys data layout and this is wrong.
Get rid of netvsc_set_hash() by switching to skb_get_hash(). This change
will also imply switching to Jenkins hash from the currently used Toeplitz
but it seems there is no good excuse for Toeplitz to stay.
Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
Acked-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/net/hyperv/netvsc_drv.c | 67 +---------------------------------------
1 file changed, 3 insertions(+), 64 deletions(-)
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -197,65 +197,6 @@ static void *init_ppi_data(struct rndis_
return ppi;
}
-union sub_key {
- u64 k;
- struct {
- u8 pad[3];
- u8 kb;
- u32 ka;
- };
-};
-
-/* Toeplitz hash function
- * data: network byte order
- * return: host byte order
- */
-static u32 comp_hash(u8 *key, int klen, void *data, int dlen)
-{
- union sub_key subk;
- int k_next = 4;
- u8 dt;
- int i, j;
- u32 ret = 0;
-
- subk.k = 0;
- subk.ka = ntohl(*(u32 *)key);
-
- for (i = 0; i < dlen; i++) {
- subk.kb = key[k_next];
- k_next = (k_next + 1) % klen;
- dt = ((u8 *)data)[i];
- for (j = 0; j < 8; j++) {
- if (dt & 0x80)
- ret ^= subk.ka;
- dt <<= 1;
- subk.k <<= 1;
- }
- }
-
- return ret;
-}
-
-static bool netvsc_set_hash(u32 *hash, struct sk_buff *skb)
-{
- struct flow_keys flow;
- int data_len;
-
- if (!skb_flow_dissect_flow_keys(skb, &flow, 0) ||
- !(flow.basic.n_proto == htons(ETH_P_IP) ||
- flow.basic.n_proto == htons(ETH_P_IPV6)))
- return false;
-
- if (flow.basic.ip_proto == IPPROTO_TCP)
- data_len = 12;
- else
- data_len = 8;
-
- *hash = comp_hash(netvsc_hash_key, HASH_KEYLEN, &flow, data_len);
-
- return true;
-}
-
static u16 netvsc_select_queue(struct net_device *ndev, struct sk_buff *skb,
void *accel_priv, select_queue_fallback_t fallback)
{
@@ -268,11 +209,9 @@ static u16 netvsc_select_queue(struct ne
if (nvsc_dev == NULL || ndev->real_num_tx_queues <= 1)
return 0;
- if (netvsc_set_hash(&hash, skb)) {
- q_idx = nvsc_dev->send_table[hash % VRSS_SEND_TAB_SIZE] %
- ndev->real_num_tx_queues;
- skb_set_hash(skb, hash, PKT_HASH_TYPE_L3);
- }
+ hash = skb_get_hash(skb);
+ q_idx = nvsc_dev->send_table[hash % VRSS_SEND_TAB_SIZE] %
+ ndev->real_num_tx_queues;
return q_idx;
}
Patches currently in stable-queue which might be from vkuznets@xxxxxxxxxx are
queue-4.4/drivers-hv-balloon-don-t-crash-when-memory-is-added-in-non-sorted-order.patch
queue-4.4/drivers-hv-avoid-vfree-on-crash.patch
queue-4.4/hv_netvsc-use-skb_get_hash-instead-of-a-homegrown-implementation.patch