From: David Bauer <mail@david-bauer.net>
Date: Tue, 21 Dec 2021 13:09:15 +0000 (+0100)
Subject: policy: don't select better candidate with bad signal
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=7e999e0874c5ef832921dfc393a3bc72879a4ec4;p=project%2Fusteer.git

policy: don't select better candidate with bad signal

Don't select a node as a better candidate where a STA has insufficient
signal to. This is the case when the roam_trigger_snr is greater than
the projected signal of the client.

This stops clients from being selected to roam to a node where the
signal is not sufficient to maintain the connection. A selection might
otherwise happen e.g. due to better channel load on the remote node.

Signed-off-by: David Bauer <mail@david-bauer.net>
---

diff --git a/policy.c b/policy.c
index 2b94d87..445abde 100644
--- a/policy.c
+++ b/policy.c
@@ -72,6 +72,18 @@ below_max_assoc(struct sta_info *si)
 	return !node->max_assoc || node->n_assoc < node->max_assoc;
 }
 
+static bool
+over_min_signal(struct sta_info *si)
+{
+	if (config.min_snr && si->signal < usteer_snr_to_signal(si->node, config.min_snr))
+		return false;
+
+	if (config.roam_trigger_snr && si->signal < usteer_snr_to_signal(si->node, config.roam_trigger_snr))
+		return false;
+	
+	return true;
+}
+
 static uint32_t
 is_better_candidate(struct sta_info *si_cur, struct sta_info *si_new)
 {
@@ -80,6 +92,9 @@ is_better_candidate(struct sta_info *si_cur, struct sta_info *si_new)
 	if (!below_max_assoc(si_new))
 		return 0;
 
+	if (!over_min_signal(si_new))
+		return 0;
+
 	if (below_assoc_threshold(si_cur, si_new) &&
 	    !below_assoc_threshold(si_new, si_cur))
 		reasons |= (1 << UEV_SELECT_REASON_NUM_ASSOC);