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

From: Simon Horman <[email-masked]>
Date: Mon, 6 Mar 2023 18:43:33 +0100

On Mon, Mar 06, 2023 at 06:12:02PM +0100, Simon Horman wrote:
> 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 <[email-masked]>
> > ---
> > 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.

Sorry, I meant to delete this one.
I don't think it is the practice in this driver.

> 
> > +
> > +	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;
> > +}
>