Am 18.10.2017 um 16:50 schrieb Ben Greear:
On 10/18/2017 12:33 AM, Johannes Berg wrote:
Hi,
The call to set the rate in the driver comes before the error
check.
if (ieee80211_hw_check(&local->hw, HAS_RATE_CONTROL)) {
ret = drv_set_bitrate_mask(local, sdata, mask);
if (ret) {
pr_err("%s: drv-set-bitrate-mask had error
return: %d\n",
sdata->dev->name, ret);
return ret;
}
}
/*
* If active validate the setting and reject it if it doesn't
leave
* at least one basic rate usable, since we really have to be
able
* to send something, and if we're an AP we have to be able to
do
* so at a basic rate so that all clients can receive it.
*/
if (rcu_access_pointer(sdata->vif.chanctx_conf) &&
sdata->vif.bss_conf.chandef.chan) {
u32 basic_rates = sdata->vif.bss_conf.basic_rates;
enum nl80211_band band = sdata-
vif.bss_conf.chandef.chan->band;
if (!(mask->control[band].legacy & basic_rates)) {
#### I changed this code so I could set a
single rate... --Ben
pr_err("%s: WARNING: no legacy rates for
band[%d] in set-bitrate-mask.\n",
sdata->dev->name, band);
}
}
Heh, that's just dumb. I guess I'll fix that by putting the test first,
no idea how that happened.
So, I think we should relax this check, at least for ath10k.
Well, yes and no. I don't think we should make ath10k special here,
and
this fixes a real problem - namely that you can set up the system
so
that you have no usable rates at all, and then you just get a
WARN_ON
and start using the lowest possible rate...
Well, there are a million ways to set up a broken system,
True, but this one actually happened in practice, for some reason, and
stopping the user from constantly shooting themselves in the foot seems
like a good idea to me. Especially if the user (or application) can't
really even know what they're getting into.
Now, the case in question was _client_ mode, but still.
and setting a single rate has a useful purpose, especially with
ath10k since it has such limited rate-setting capabilities.
You're stretching the definition of "useful purpose" a bit here though,
you're about the only one who's ever going to need to set a single
rate.
People trying to do regulatory testing want this feature, and other people
that are not me also like to test with specific rates. Still a
small-ish set
of people, but bigger than just me at least.
Till now i was interviewing different people who was asking for this for
ath9k-htc. So I would say we have:
- academical researchers
- testers
- R&D
- exploit and penetration testers
- HAM
- just hackers
As for me, it sounds a s lot.
--
Regards,
Oleksij
