linux-kernel - [PATCH] wifi: mt76: mt7925: fix kernel warning in MLO ROC setup when channel not configured

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Message-ID: <20260102200315.290015-3-zbowling@gmail.com>
Date: Fri,  2 Jan 2026 12:03:11 -0800
From: Zac Bowling <zbowling@...il.com>
To: zbowling@...il.com
Cc: deren.wu@...iatek.com,
	kvalo@...nel.org,
	linux-kernel@...r.kernel.org,
	linux-mediatek@...ts.infradead.org,
	linux-wireless@...r.kernel.org,
	lorenzo@...nel.org,
	nbd@....name,
	ryder.lee@...iatek.com,
	sean.wang@...iatek.com
Subject: [PATCH] wifi: mt76: mt7925: fix kernel warning in MLO ROC setup when channel not configured

mt7925_mcu_set_mlo_roc() uses WARN_ON_ONCE() to check if link_conf or
channel is NULL. However, during MLO AP setup, it's normal for the
channel to not be configured yet when this function is called. The
WARN_ON_ONCE triggers a kernel warning/oops that makes the system
appear to have crashed, even though it's just a timing issue.

Replace WARN_ON_ONCE with regular NULL checks and return -ENOLINK to
indicate the link isn't fully configured yet. This allows the upper
layers to retry when the link is ready, without spamming the kernel
log with warnings.

Also add a check for mconf in the first loop to match the pattern
used in the second loop, preventing potential NULL dereference.

This fixes kernel oops reported during MLO AP setup on OpenWrt with
MT7925E hardware.

Signed-off-by: Zac Bowling <zac@...bowling.com>
---
 mt7925/mcu.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/mt7925/mcu.c b/mt7925/mcu.c
index bd38807e..b0bbeb5a 100644
--- a/mt7925/mcu.c
+++ b/mt7925/mcu.c
@@ -1337,15 +1337,23 @@ int mt7925_mcu_set_mlo_roc(struct mt792x_bss_conf *mconf, u16 sel_links,
 	for (i = 0; i < ARRAY_SIZE(links); i++) {
 		links[i].id = i ? __ffs(~BIT(mconf->link_id) & sel_links) :
 				 mconf->link_id;
+
 		link_conf = mt792x_vif_to_bss_conf(vif, links[i].id);
-		if (WARN_ON_ONCE(!link_conf))
-			return -EPERM;
+		if (!link_conf)
+			return -ENOLINK;
 
 		links[i].chan = link_conf->chanreq.oper.chan;
-		if (WARN_ON_ONCE(!links[i].chan))
-			return -EPERM;
+		if (!links[i].chan)
+			/* Channel not configured yet - this can happen during
+			 * MLO AP setup when links are being added sequentially.
+			 * Return -ENOLINK to indicate link not ready.
+			 */
+			return -ENOLINK;
 
 		links[i].mconf = mt792x_vif_to_link(mvif, links[i].id);
+		if (!links[i].mconf)
+			return -ENOLINK;
+
 		links[i].tag = links[i].id == mconf->link_id ?
 			       UNI_ROC_ACQUIRE : UNI_ROC_SUB_LINK;
 
@@ -1359,8 +1367,8 @@ int mt7925_mcu_set_mlo_roc(struct mt792x_bss_conf *mconf, u16 sel_links,
 		type = MT7925_ROC_REQ_JOIN;
 
 	for (i = 0; i < ARRAY_SIZE(links) && i < hweight16(vif->active_links); i++) {
-		if (WARN_ON_ONCE(!links[i].mconf || !links[i].chan))
-			continue;
+		if (!links[i].mconf || !links[i].chan)
+			return -ENOLINK;
 
 		chan = links[i].chan;
 		center_ch = ieee80211_frequency_to_channel(chan->center_freq);
-- 
2.51.0