wifi: cfg80211: remove 5/10 MHz channel support

Remove WIPHY_FLAG_SUPPORTS_5_10_MHZ and 5/10 MHz channel
width support. We contemplated this back in early 2023
and didn't do it yet, but nobody stepped up to maintain
it.

It's already _mostly_ dead code since it can really only
be used for AP and maybe IBSS and monitor, but not on a
client since there's no way to scan (and hasn't been in
a very long time, if ever), so the only thing that ever
could really happen with it was run syzbot and trip over
assumptions in the code.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Reviewed-by: Lachlan Hodges <lachlan.hodges@morsemicro.com>
Link: https://patch.msgid.link/20260529084502.080c5885f0b7.I77cc94485b523c3c006005b9233db13cd4e077b3@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

8 files changed, 12 insertions, 50 deletions

diff --git a/drivers/net/wireless/ath/ath5k/base.c b/drivers/net/wireless/ath/ath5k/base.c
index 6ca31d4ea437..610a3321b497 100644
--- a/drivers/net/wireless/ath/ath5k/base.c
+++ b/drivers/net/wireless/ath/ath5k/base.c
@@ -2600,8 +2600,6 @@ ath5k_init_ah(struct ath5k_hw *ah, const struct ath_bus_ops *bus_ops)
 	/* SW support for IBSS_RSN is provided by mac80211 */
 	hw->wiphy->flags |= WIPHY_FLAG_IBSS_RSN;
 
-	hw->wiphy->flags |= WIPHY_FLAG_SUPPORTS_5_10_MHZ;
-
 	/* both antennas can be configured as RX or TX */
 	hw->wiphy->available_antennas_tx = 0x3;
 	hw->wiphy->available_antennas_rx = 0x3;
diff --git a/drivers/net/wireless/ath/ath9k/init.c b/drivers/net/wireless/ath/ath9k/init.c
index e1a67e8ed09f..2f0c4ef86b7e 100644
--- a/drivers/net/wireless/ath/ath9k/init.c
+++ b/drivers/net/wireless/ath/ath9k/init.c
@@ -957,7 +957,6 @@ static void ath9k_set_hw_capab(struct ath_softc *sc, struct ieee80211_hw *hw)
 	hw->wiphy->flags |= WIPHY_FLAG_IBSS_RSN;
 	hw->wiphy->flags |= WIPHY_FLAG_SUPPORTS_TDLS;
 	hw->wiphy->flags |= WIPHY_FLAG_HAS_REMAIN_ON_CHANNEL;
-	hw->wiphy->flags |= WIPHY_FLAG_SUPPORTS_5_10_MHZ;
 	hw->wiphy->flags |= WIPHY_FLAG_HAS_CHANNEL_SWITCH;
 	hw->wiphy->flags |= WIPHY_FLAG_AP_UAPSD;
 
diff --git a/drivers/net/wireless/virtual/mac80211_hwsim_main.c b/drivers/net/wireless/virtual/mac80211_hwsim_main.c
index 6ea082157307..4926122d6648 100644
--- a/drivers/net/wireless/virtual/mac80211_hwsim_main.c
+++ b/drivers/net/wireless/virtual/mac80211_hwsim_main.c
@@ -5903,7 +5903,6 @@ static int mac80211_hwsim_new_radio(struct genl_info *info,
 	hw->wiphy->flags |= WIPHY_FLAG_SUPPORTS_TDLS |
 			    WIPHY_FLAG_HAS_REMAIN_ON_CHANNEL |
 			    WIPHY_FLAG_AP_UAPSD |
-			    WIPHY_FLAG_SUPPORTS_5_10_MHZ |
 			    WIPHY_FLAG_HAS_CHANNEL_SWITCH;
 	hw->wiphy->flags |= WIPHY_FLAG_IBSS_RSN;
 	hw->wiphy->features |= NL80211_FEATURE_ACTIVE_MONITOR |
diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 69dc9a978861..f91a71c7f4db 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -5676,7 +5676,6 @@ struct cfg80211_ops {
  *	responds to probe-requests in hardware.
  * @WIPHY_FLAG_OFFCHAN_TX: Device supports direct off-channel TX.
  * @WIPHY_FLAG_HAS_REMAIN_ON_CHANNEL: Device supports remain-on-channel call.
- * @WIPHY_FLAG_SUPPORTS_5_10_MHZ: Device supports 5 MHz and 10 MHz channels.
  * @WIPHY_FLAG_HAS_CHANNEL_SWITCH: Device supports channel switch in
  *	beaconing mode (AP, IBSS, Mesh, ...).
  * @WIPHY_FLAG_SUPPORTS_EXT_KEK_KCK: The device supports bigger kek and kck keys
@@ -5716,7 +5715,6 @@ enum wiphy_flags {
 	WIPHY_FLAG_AP_PROBE_RESP_OFFLOAD	= BIT(19),
 	WIPHY_FLAG_OFFCHAN_TX			= BIT(20),
 	WIPHY_FLAG_HAS_REMAIN_ON_CHANNEL	= BIT(21),
-	WIPHY_FLAG_SUPPORTS_5_10_MHZ		= BIT(22),
 	WIPHY_FLAG_HAS_CHANNEL_SWITCH		= BIT(23),
 	WIPHY_FLAG_NOTIFY_REGDOM_BY_DRIVER	= BIT(24),
 	WIPHY_FLAG_CHANNEL_CHANGE_ON_BEACON     = BIT(25),
diff --git a/net/wireless/chan.c b/net/wireless/chan.c
index f0811efb5d0f..7f6af1790736 100644
--- a/net/wireless/chan.c
+++ b/net/wireless/chan.c
@@ -280,12 +280,6 @@ int nl80211_chan_width_to_mhz(enum nl80211_chan_width chan_width)
 	case NL80211_CHAN_WIDTH_16:
 		mhz = 16;
 		break;
-	case NL80211_CHAN_WIDTH_5:
-		mhz = 5;
-		break;
-	case NL80211_CHAN_WIDTH_10:
-		mhz = 10;
-		break;
 	case NL80211_CHAN_WIDTH_20:
 	case NL80211_CHAN_WIDTH_20_NOHT:
 		mhz = 20;
@@ -347,8 +341,6 @@ cfg80211_chandef_valid_control_freq(const struct cfg80211_chan_def *chandef,
 				    u32 control_freq)
 {
 	switch (chandef->width) {
-	case NL80211_CHAN_WIDTH_5:
-	case NL80211_CHAN_WIDTH_10:
 	case NL80211_CHAN_WIDTH_20:
 	case NL80211_CHAN_WIDTH_20_NOHT:
 	case NL80211_CHAN_WIDTH_1:
@@ -415,8 +407,6 @@ bool cfg80211_chandef_valid(const struct cfg80211_chan_def *chandef)
 		return false;
 
 	switch (chandef->width) {
-	case NL80211_CHAN_WIDTH_5:
-	case NL80211_CHAN_WIDTH_10:
 	case NL80211_CHAN_WIDTH_20:
 	case NL80211_CHAN_WIDTH_20_NOHT:
 		if (ieee80211_chandef_to_khz(chandef) !=
@@ -803,18 +793,16 @@ _cfg80211_chandef_compatible(const struct cfg80211_chan_def *c1,
 		return NULL;
 
 	/*
-	 * can't be compatible if one of them is 5/10 MHz or S1G
+	 * can't be compatible if one of them is S1G
 	 * but they don't have the same width.
 	 */
-#define NARROW_OR_S1G(width)	((width) == NL80211_CHAN_WIDTH_5 || \
-				 (width) == NL80211_CHAN_WIDTH_10 || \
-				 (width) == NL80211_CHAN_WIDTH_1 || \
-				 (width) == NL80211_CHAN_WIDTH_2 || \
-				 (width) == NL80211_CHAN_WIDTH_4 || \
-				 (width) == NL80211_CHAN_WIDTH_8 || \
-				 (width) == NL80211_CHAN_WIDTH_16)
-
-	if (NARROW_OR_S1G(c1->width) || NARROW_OR_S1G(c2->width))
+#define IS_S1G(width)	((width) == NL80211_CHAN_WIDTH_1 || \
+			 (width) == NL80211_CHAN_WIDTH_2 || \
+			 (width) == NL80211_CHAN_WIDTH_4 || \
+			 (width) == NL80211_CHAN_WIDTH_8 || \
+			 (width) == NL80211_CHAN_WIDTH_16)
+
+	if (IS_S1G(c1->width) || IS_S1G(c2->width))
 		return NULL;
 
 	/*
@@ -1506,13 +1494,6 @@ bool _cfg80211_chandef_usable(struct wiphy *wiphy,
 	control_freq = chandef->chan->center_freq;
 
 	switch (chandef->width) {
-	case NL80211_CHAN_WIDTH_5:
-		width = 5;
-		break;
-	case NL80211_CHAN_WIDTH_10:
-		prohibited_flags |= IEEE80211_CHAN_NO_10MHZ;
-		width = 10;
-		break;
 	case NL80211_CHAN_WIDTH_20:
 		if (!ht_cap->ht_supported &&
 		    chandef->chan->band != NL80211_BAND_6GHZ)
diff --git a/net/wireless/core.c b/net/wireless/core.c
index 62ab5e4639be..3dcf63b04c41 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -917,9 +917,7 @@ int wiphy_register(struct wiphy *wiphy)
 				  BIT(NL80211_CHAN_WIDTH_80) |
 				  BIT(NL80211_CHAN_WIDTH_80P80) |
 				  BIT(NL80211_CHAN_WIDTH_160) |
-				  BIT(NL80211_CHAN_WIDTH_320) |
-				  BIT(NL80211_CHAN_WIDTH_5) |
-				  BIT(NL80211_CHAN_WIDTH_10))))
+				  BIT(NL80211_CHAN_WIDTH_320))))
 			return -EINVAL;
 	}
 
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index cdb5e9b77143..19244708f5c3 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -3450,11 +3450,6 @@ static int nl80211_send_wiphy(struct cfg80211_registered_device *rdev,
 		if (nl80211_send_coalesce(msg, rdev))
 			goto nla_put_failure;
 
-		if ((rdev->wiphy.flags & WIPHY_FLAG_SUPPORTS_5_10_MHZ) &&
-		    (nla_put_flag(msg, NL80211_ATTR_SUPPORT_5_MHZ) ||
-		     nla_put_flag(msg, NL80211_ATTR_SUPPORT_10_MHZ)))
-			goto nla_put_failure;
-
 		if (rdev->wiphy.max_ap_assoc_sta &&
 		    nla_put_u32(msg, NL80211_ATTR_MAX_AP_ASSOC_STA,
 				rdev->wiphy.max_ap_assoc_sta))
@@ -4085,10 +4080,9 @@ static int _nl80211_parse_chandef(struct cfg80211_registered_device *rdev,
 		return -EINVAL;
 	}
 
-	if ((chandef->width == NL80211_CHAN_WIDTH_5 ||
-	     chandef->width == NL80211_CHAN_WIDTH_10) &&
-	    !(rdev->wiphy.flags & WIPHY_FLAG_SUPPORTS_5_10_MHZ)) {
-		NL_SET_ERR_MSG(extack, "5/10 MHz not supported");
+	if (chandef->width == NL80211_CHAN_WIDTH_5 ||
+	    chandef->width == NL80211_CHAN_WIDTH_10) {
+		NL_SET_ERR_MSG(extack, "5/10 MHz not supported any more");
 		return -EINVAL;
 	}
 
@@ -13410,8 +13404,6 @@ static int nl80211_join_ibss(struct sk_buff *skb, struct genl_info *info)
 		return -EINVAL;
 
 	switch (ibss.chandef.width) {
-	case NL80211_CHAN_WIDTH_5:
-	case NL80211_CHAN_WIDTH_10:
 	case NL80211_CHAN_WIDTH_20_NOHT:
 		break;
 	case NL80211_CHAN_WIDTH_20:
diff --git a/net/wireless/util.c b/net/wireless/util.c
index 8dd7545b9097..24527bf321b2 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -2304,9 +2304,6 @@ bool ieee80211_chandef_to_operating_class(struct cfg80211_chan_def *chandef,
 	case NL80211_CHAN_WIDTH_80P80:
 		vht_opclass = 130;
 		break;
-	case NL80211_CHAN_WIDTH_10:
-	case NL80211_CHAN_WIDTH_5:
-		return false; /* unsupported for now */
 	default:
 		vht_opclass = 0;
 		break;