Messages in this thread | | | Date | Fri, 17 Feb 2023 10:43:38 +0800 | Subject | Re: [PATCH net-next v1 3/3] net/mlx5e: TC, Add support for VxLAN GBP encap/decap flows offload | From | Gavin Li <> |
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On 2/16/2023 11:19 PM, Alexander Lobakin wrote: > External email: Use caution opening links or attachments > > > From: Gavin Li <gavinl@nvidia.com> > Date: Thu, 16 Feb 2023 16:40:33 +0800 > >> On 2/16/2023 1:01 AM, Alexander Lobakin wrote: >>> External email: Use caution opening links or attachments >>> >>> >>> From: Gavin Li <gavinl@nvidia.com> >>> Date: Wed, 15 Feb 2023 16:30:04 +0800 >>> >>>> On 2/15/2023 11:36 AM, Gavin Li wrote: >>>>> External email: Use caution opening links or attachments >>>>> >>>>> >>>>> On 2/14/2023 11:26 PM, Alexander Lobakin wrote: >>>>>> External email: Use caution opening links or attachments >>>>>> >>>>>> >>>>>> From: Gavin Li <gavinl@nvidia.com> >>>>>> Date: Tue, 14 Feb 2023 15:41:37 +0200 >>> [...] >>> >>>>>>> @@ -96,6 +99,70 @@ static int mlx5e_gen_ip_tunnel_header_vxlan(char >>>>>>> buf[], >>>>>>> udp->dest = tun_key->tp_dst; >>>>>>> vxh->vx_flags = VXLAN_HF_VNI; >>>>>>> vxh->vx_vni = vxlan_vni_field(tun_id); >>>>>>> + if (tun_key->tun_flags & TUNNEL_VXLAN_OPT) { >>>>>>> + md = ip_tunnel_info_opts((struct ip_tunnel_info >>>>>>> *)e->tun_info); >>>>>>> + vxlan_build_gbp_hdr(vxh, tun_key->tun_flags, >>>>>>> + (struct vxlan_metadata *)md); >>>>>> Maybe constify both ip_tunnel_info_opts() and vxlan_build_gbp_hdr() >>>>>> arguments instead of working around by casting away? >>>>> ACK. Sorry for the confusion---I misunderstood the comment. >>>> This ip_tunnel_info_opts is tricky to use const to annotate the arg >>>> because it will have to cast from const to non-const again upon >>>> returning. >>> It's okay to cast away for the `void *` returned. >>> Alternatively, use can convert it to a macro and use >>> __builtin_choose_expr() or _Generic to return const or non-const >>> depending on whether the argument is constant. That's what was recently >>> done for container_of() IIRC. >> I've fixed vxlan_build_gbp_hdr in V2. For ip_tunnel_info_opts, it's >> confusing to me. >> >> It would be as below after constifying the parameter. >> >> static inline void *ip_tunnel_info_opts(const struct ip_tunnel_info *info) >> { >> return (void *)(info + 1); >> } >> Is there any value gained by this change? > You wouldn't need to W/A it each time in each driver, just do it once in > the inline itself. > I did it once in __skb_header_pointer()[0] to be able to pass data > pointer as const to optimize code a bit and point out explicitly that > the function doesn't modify the packet anyhow, don't see any reason to > not do the same here. > Or, as I said, you can use macros + __builtin_choose_expr() or _Generic. > container_of_const() uses the latter[1]. A __builtin_choose_expr() > variant could rely on the __same_type() macro to check whether the > pointer passed from the driver const or not. ACK > >>>>>>> + } >>>>>>> + >>>>>>> + return 0; >>>>>>> +} >>> [...] >>> >>> Thanks, >>> Olek > [0] > https://elixir.bootlin.com/linux/v6.2-rc8/source/include/linux/skbuff.h#L3992 > [1] > https://elixir.bootlin.com/linux/v6.2-rc8/source/include/linux/container_of.h#L33 > > Thanks, > Olek
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