The scheduled scan matchsets were intended to be a list of filters, with the found BSS having to pass at least one of them to be passed to the host. When the RSSI attribute was added, however, this was broken and currently wpa_supplicant adds that attribute in its own matchset; however, it doesn't intend that to mean that anything that passes the RSSI filter should be passed to the host, instead it wants it to mean that everything needs to also have higher RSSI. This is semantically problematic because we have a list of filters like [ SSID1, SSID2, SSID3, RSSI ] with no real indication which one should be OR'ed and which one AND'ed. To fix this, move the RSSI filter attribute into each matchset. As we need to stay backward compatible, treat a matchset with only the RSSI attribute as a "default RSSI filter" for all other matchsets, but only if there are other matchsets (an RSSI-only matchset by itself is still desirable.) To make driver implementation easier, keep a global min_rssi_thold for the entire request as well. The only affected driver is ath6kl. I found this when I looked into the code after Raja Mani submitted a patch fixing the n_match_sets calculation to disregard the RSSI, but that patch didn't address the semantic issue.
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| @@ -2467,9 +2467,15 @@ enum nl80211_reg_rule_attr { · 2466 unmodified lines | |||
| 2467 | * enum nl80211_sched_scan_match_attr - scheduled scan match attributes | 2467 | * enum nl80211_sched_scan_match_attr - scheduled scan match attributes |
| 2468 | * @__NL80211_SCHED_SCAN_MATCH_ATTR_INVALID: attribute number 0 is reserved | 2468 | * @__NL80211_SCHED_SCAN_MATCH_ATTR_INVALID: attribute number 0 is reserved |
| 2469 | * @NL80211_SCHED_SCAN_MATCH_ATTR_SSID: SSID to be used for matching, | 2469 | * @NL80211_SCHED_SCAN_MATCH_ATTR_SSID: SSID to be used for matching, |
| 2470 | * only report BSS with matching SSID. | 2470 | * only report BSS with matching SSID. |
| 2471 | * @NL80211_SCHED_SCAN_MATCH_ATTR_RSSI: RSSI threshold (in dBm) for reporting a | 2471 | * @NL80211_SCHED_SCAN_MATCH_ATTR_RSSI: RSSI threshold (in dBm) for reporting a |
| 2472 | * BSS in scan results. Filtering is turned off if not specified. | 2472 | * BSS in scan results. Filtering is turned off if not specified. Note that |
| 2473 | * if this attribute is in a match set of its own, then it is treated as | ||
| 2474 | * the default value for all matchsets with an SSID, rather than being a | ||
| 2475 | * matchset of its own without an RSSI filter. This is due to problems with | ||
| 2476 | * how this API was implemented in the past. Also, due to the same problem, | ||
| 2477 | * the only way to create a matchset with only an RSSI filter (with this | ||
| 2478 | * attribute) is if there's only a single matchset with the RSSI attribute. | ||
| 2473 | * @NL80211_SCHED_SCAN_MATCH_ATTR_MAX: highest scheduled scan filter | 2479 | * @NL80211_SCHED_SCAN_MATCH_ATTR_MAX: highest scheduled scan filter |
| 2474 | * attribute number currently defined | 2480 | * attribute number currently defined |
| 2475 | * @__NL80211_SCHED_SCAN_MATCH_ATTR_AFTER_LAST: internal use | 2481 | * @__NL80211_SCHED_SCAN_MATCH_ATTR_AFTER_LAST: internal use |