[ovs-dev] [PATCH V3 14/24] datapath: don't call pad_packet if not necessary

[Greg Rose]

From: Tonghao Zhang <xiangxia.m....@gmail.com>

Upstream commit:
    commit 61ca533c0e94104c35fcb7858a23ec9a05d78143
    Author: Tonghao Zhang <xiangxia.m....@gmail.com>
    Date:   Thu Nov 14 23:51:08 2019 +0800

    net: openvswitch: don't call pad_packet if not necessary

    The nla_put_u16/nla_put_u32 makes sure that
    *attrlen is align. The call tree is that:

    nla_put_u16/nla_put_u32
      -> nla_put                attrlen = sizeof(u16) or sizeof(u32)
      -> __nla_put              attrlen
      -> __nla_reserve  attrlen
      -> skb_put(skb, nla_total_size(attrlen))

    nla_total_size returns the total length of attribute
    including padding.

    Cc: Joe Stringer <j...@ovn.org>
    Cc: William Tu <u9012...@gmail.com>
    Signed-off-by: Tonghao Zhang <xiangxia.m....@gmail.com>
    Acked-by: Pravin B Shelar <pshe...@ovn.org>
    Signed-off-by: David S. Miller <da...@davemloft.net>

Cc: Tonghao Zhang <xiangxia.m....@gmail.com>
Reviewed-by: Tonghao Zhang <xiangxia.m....@gmail.com>
Signed-off-by: Greg Rose <gvrose8...@gmail.com>
---
 datapath/datapath.c | 22 ++++++++--------------
 1 file changed, 8 insertions(+), 14 deletions(-)

diff --git a/datapath/datapath.c b/datapath/datapath.c
index f04ce210c..b9ac67635 100644
--- a/datapath/datapath.c
+++ b/datapath/datapath.c
@@ -512,23 +512,17 @@ static int queue_userspace_packet(struct datapath *dp, 
struct sk_buff *skb,
        }
 
        /* Add OVS_PACKET_ATTR_MRU */
-       if (upcall_info->mru) {
-               if (nla_put_u16(user_skb, OVS_PACKET_ATTR_MRU,
-                               upcall_info->mru)) {
-                       err = -ENOBUFS;
-                       goto out;
-               }
-               pad_packet(dp, user_skb);
+       if (upcall_info->mru &&
+           nla_put_u16(user_skb, OVS_PACKET_ATTR_MRU, upcall_info->mru)) {
+               err = -ENOBUFS;
+               goto out;
        }
 
        /* Add OVS_PACKET_ATTR_LEN when packet is truncated */
-       if (cutlen > 0) {
-               if (nla_put_u32(user_skb, OVS_PACKET_ATTR_LEN,
-                               skb->len)) {
-                       err = -ENOBUFS;
-                       goto out;
-               }
-               pad_packet(dp, user_skb);
+       if (cutlen > 0 &&
+           nla_put_u32(user_skb, OVS_PACKET_ATTR_LEN, skb->len)) {
+               err = -ENOBUFS;
+               goto out;
        }
 
        /* Add OVS_PACKET_ATTR_HASH */
-- 
2.17.1

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