netdev - Re: [PATCH v8 3/5] mac80211_hwsim: add PMSR request support via virtio

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Date:   Mon, 6 Mar 2023 18:12:02 +0100
From:   Simon Horman <simon.horman@...igine.com>
To:     Jaewan Kim <jaewan@...gle.com>
Cc:     gregkh@...uxfoundation.org, johannes@...solutions.net,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        kernel-team@...roid.com, adelva@...gle.com
Subject: Re: [PATCH v8 3/5] mac80211_hwsim: add PMSR request support via
 virtio

On Thu, Mar 02, 2023 at 04:03:08PM +0000, Jaewan Kim wrote:
> PMSR (a.k.a. peer measurement) is generalized measurement between two
> Wi-Fi devices. And currently FTM (a.k.a. fine time measurement or flight
> time measurement) is the one and only measurement. FTM is measured by
> RTT (a.k.a. round trip time) of packets between two Wi-Fi devices.
> 
> Add necessary functionalities for mac80211_hwsim to start PMSR request by
> passthrough the request to wmediumd via virtio. mac80211_hwsim can't
> measure RTT for real because mac80211_hwsim the software simulator and
> packets are sent almost immediately for real. This change expect wmediumd
> to have all the location information of devices, so passthrough requests
> to wmediumd.
> 
> In detail, add new mac80211_hwsim command HWSIM_CMD_ABORT_PMSR. When
> mac80211_hwsim receives the PMSR start request via
> ieee80211_ops.start_pmsr, the received cfg80211_pmsr_request is resent to
> the wmediumd with command HWSIM_CMD_START_PMSR and attribute
> HWSIM_ATTR_PMSR_REQUEST. The attribute is formatted as the same way as
> nl80211_pmsr_start() expects.
> 
> Signed-off-by: Jaewan Kim <jaewan@...gle.com>
> ---
> V7->V8: Export nl80211_send_chandef directly and instead of creating
>         wrapper.
> V7: Initial commit (split from previously large patch)
> ---
>  drivers/net/wireless/mac80211_hwsim.c | 207 +++++++++++++++++++++++++-
>  drivers/net/wireless/mac80211_hwsim.h |   6 +
>  2 files changed, 212 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/mac80211_hwsim.c b/drivers/net/wireless/mac80211_hwsim.c
> index 79476d55c1ca..691b83140d57 100644
> --- a/drivers/net/wireless/mac80211_hwsim.c
> +++ b/drivers/net/wireless/mac80211_hwsim.c
> @@ -721,6 +721,8 @@ struct mac80211_hwsim_data {
>  
>  	/* only used when pmsr capability is supplied */
>  	struct cfg80211_pmsr_capabilities pmsr_capa;
> +	struct cfg80211_pmsr_request *pmsr_request;
> +	struct wireless_dev *pmsr_request_wdev;
>  
>  	struct mac80211_hwsim_link_data link_data[IEEE80211_MLD_MAX_NUM_LINKS];
>  };
> @@ -3139,6 +3141,208 @@ static int mac80211_hwsim_change_sta_links(struct ieee80211_hw *hw,
>  	return 0;
>  }
>  
> +static int mac80211_hwsim_send_pmsr_ftm_request_peer(struct sk_buff *msg,
> +						     struct cfg80211_pmsr_ftm_request_peer *request)
> +{
> +	struct nlattr *ftm;
> +
> +	if (!request->requested)
> +		return -EINVAL;
> +
> +	ftm = nla_nest_start(msg, NL80211_PMSR_TYPE_FTM);
> +	if (!ftm)
> +		return -ENOBUFS;
> +
> +	if (nla_put_u32(msg, NL80211_PMSR_FTM_REQ_ATTR_PREAMBLE, request->preamble))

nit: I suspect that you need to invoke nla_nest_cancel() in
     error paths to unwind nla_nest_start() calls.

> +		return -ENOBUFS;
> +

...

> +static int mac80211_hwsim_send_pmsr_request(struct sk_buff *msg,
> +					    struct cfg80211_pmsr_request *request)
> +{
> +	int err;
> +	struct nlattr *pmsr = nla_nest_start(msg, NL80211_ATTR_PEER_MEASUREMENTS);
nit: reverse xmas tree - longest line to shortest - for local variable
     declarations.

> +
> +	if (!pmsr)
> +		return -ENOBUFS;
> +
> +	if (nla_put_u32(msg, NL80211_ATTR_TIMEOUT, request->timeout))
> +		return -ENOBUFS;
> +
> +	if (!is_zero_ether_addr(request->mac_addr)) {
> +		if (nla_put(msg, NL80211_ATTR_MAC, ETH_ALEN, request->mac_addr))
> +			return -ENOBUFS;
> +		if (nla_put(msg, NL80211_ATTR_MAC_MASK, ETH_ALEN, request->mac_addr_mask))
> +			return -ENOBUFS;
> +	}
> +
> +	for (int i = 0; i < request->n_peers; i++) {

nit: the scope of err can be reduced to this block.

> +		err = mac80211_hwsim_send_pmsr_request_peer(msg, &request->peers[i]);
> +		if (err)
> +			return err;
> +	}
> +
> +	nla_nest_end(msg, pmsr);
> +
> +	return 0;
> +}