RE: [PATCH rtw-next 2/2] wifi: rtw88: usb: only let the frames a dozing station needs use the after-DTIM queue

[Ping-Ke Shih]

Mehmet Fide <mehmet.fide@xxxxxxxxx> wrote:
> From: Mehmet Fide <mehmet.fide@xxxxxxxxxxxxxxxxxx>
> 
> With the budget in place the high queue can no longer take the chip
> down, but ordinary chatter still competes with the frames a sleeping
> station actually needs. mac80211 marks every broadcast and multicast
> frame with IEEE80211_TX_CTL_SEND_AFTER_DTIM while a station dozes,
> mDNS and SSDP included, so under normal traffic the budget is spent on
> frames nobody waits for.
> 
> Do what the vendor driver does with its default "allow special" high
> queue filter: admit only ARP, EAPOL and DHCP to the after-DTIM path,
> the frames a station coming out of power save has to see; everything
> else goes out on its access category queue at line rate. Encrypted
> group frames carry the IV between the header and the SNAP header, so
> the parser accounts for hw_key->iv_len. With the filter in place the
> page pool stays at 1803 through the same 180 second storm, a DHCP
> flood still takes the after-DTIM path (and is then held by the budget),
> and join/ping cycling without power save is unchanged (10/10).
> 
> Signed-off-by: Mehmet Fide <mehmet.fide@xxxxxxxxxxxxxxxxxx>
> ---
>  drivers/net/wireless/realtek/rtw88/usb.c | 42 +++++++++++++++++++++++-
>  1 file changed, 41 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/realtek/rtw88/usb.c b/drivers/net/wireless/realtek/rtw88/usb.c
> index 80965e5ea778..dd65b304b2c7 100644
> --- a/drivers/net/wireless/realtek/rtw88/usb.c
> +++ b/drivers/net/wireless/realtek/rtw88/usb.c
> @@ -5,6 +5,9 @@
>  #include <linux/module.h>
>  #include <linux/usb.h>
>  #include <linux/mutex.h>
> +#include <linux/ip.h>
> +#include <linux/udp.h>
> +#include <linux/unaligned.h>

The existing is messed already. But could please put them in increasing
alphabet order? (only apply the part of '#include <linux/*')

>  #include "main.h"
>  #include "debug.h"
>  #include "mac.h"
> @@ -562,6 +565,43 @@ static int rtw_usb_write_data_h2c(struct rtw_dev *rtwdev, u8 *buf, u32 size)
>         return rtw_usb_write_data(rtwdev, &pkt_info, buf);
>  }
> 
> +static bool rtw_usb_bmc_needs_dtim(struct sk_buff *skb)
> +{
> +       struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
> +       struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
> +       unsigned int hdrlen = ieee80211_hdrlen(hdr->frame_control);
> +       unsigned int paylen = sizeof(rfc1042_header) + sizeof(__be16);

In reverse X'mas tree order. If you want keep 'struct' and 'unsigned int'
together individually. We can have

	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
	unsigned int paylen = sizeof(rfc1042_header) + sizeof(__be16);
	unsigned int hdrlen = ieee80211_hdrlen(hdr->frame_control);


> +       const struct udphdr *udp;
> +       const struct iphdr *ip;
> +       const u8 *snap;
> +       __be16 proto;
> +
> +       if (info->control.hw_key)
> +               hdrlen += info->control.hw_key->iv_len;
> +
> +       if (skb->len < hdrlen + paylen)
> +               return false;
> +
> +       snap = skb->data + hdrlen;
> +       proto = get_unaligned((__be16 *)(snap + sizeof(rfc1042_header)));
> +
> +       if (proto == htons(ETH_P_ARP) || proto == htons(ETH_P_PAE))

Can we just 'skb->protocol == htons(ETH_P_ARP)' ?

> +               return true;
> +
> +       if (proto != htons(ETH_P_IP) || skb->len < hdrlen + paylen + sizeof(*ip))
> +               return false;
> +
> +       ip = (const struct iphdr *)(snap + paylen);
> +       if (ip->protocol != IPPROTO_UDP)
> +               return false;
> +
> +       udp = (const struct udphdr *)((const u8 *)ip + ip->ihl * 4);
> +       if (skb->len < (unsigned int)((const u8 *)udp - skb->data) + sizeof(*udp))
> +               return false;

udphdr = udp_hdr(skb); ?

reference to rtw89_core_tx_btc_spec_pkt_notify().

> +
> +       return udp->dest == htons(67) || udp->dest == htons(68);
> +}
> +
>  #define RTW_USB_HIQ_RATE       10
>  #define RTW_USB_HIQ_BURST      16
> 
> @@ -605,7 +645,7 @@ static u8 rtw_usb_tx_queue_mapping_to_qsel(struct rtw_usb *rtwusb,
>         else if (is_broadcast_ether_addr(hdr->addr1) ||
>                  is_multicast_ether_addr(hdr->addr1))
>                 qsel = (info->flags & IEEE80211_TX_CTL_SEND_AFTER_DTIM) &&
> -                      rtw_usb_hiq_take(rtwusb) ?
> +                      rtw_usb_bmc_needs_dtim(skb) && rtw_usb_hiq_take(rtwusb) ?
>                        TX_DESC_QSEL_HIGH : skb->priority;
>         else if (skb_get_queue_mapping(skb) <= IEEE80211_AC_BK)
>                 qsel = skb->priority;
> --
> 2.54.0