wifi: mt76: Move RCU section in mt7996_mcu_add_rate_ctrl_fixed()

Since mt7996_mcu_set_fixed_field() can't be executed in a RCU critical
section, move RCU section in mt7996_mcu_add_rate_ctrl_fixed() and run
mt7996_mcu_set_fixed_field() in non-atomic context. This is a
preliminary patch to fix a 'sleep while atomic' issue in
mt7996_mac_sta_rc_work().

Fixes: 0762bdd30279 ("wifi: mt76: mt7996: rework mt7996_mac_sta_rc_work to support MLO")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://patch.msgid.link/20250605-mt7996-sleep-while-atomic-v1-3-d46d15f9203c@kernel.org
Signed-off-by: Felix Fietkau <nbd@nbd.name>

diff --git a/drivers/net/wireless/mediatek/mt76/mt7996/mcu.c b/drivers/net/wireless/mediatek/mt76/mt7996/mcu.c
index 33c61e795b734e84af42fdea5ba33975e3e3365a..742497ba2a6bcd73e3660e626e4a756d79a467bf 100644 (file)
--- a/drivers/net/wireless/mediatek/mt76/mt7996/mcu.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7996/mcu.c
@@ -1977,51 +1977,74 @@ error_unlock:
 }
 
 static int
-mt7996_mcu_add_rate_ctrl_fixed(struct mt7996_dev *dev,
-                              struct ieee80211_link_sta *link_sta,
-                              struct mt7996_vif_link *link,
-                              struct mt7996_sta_link *msta_link,
-                              u8 link_id)
+mt7996_mcu_add_rate_ctrl_fixed(struct mt7996_dev *dev, struct mt7996_sta *msta,
+                              struct ieee80211_vif *vif, u8 link_id)
 {
-       struct cfg80211_chan_def *chandef = &link->phy->mt76->chandef;
-       struct cfg80211_bitrate_mask *mask = &link->bitrate_mask;
-       enum nl80211_band band = chandef->chan->band;
-       struct mt7996_sta *msta = msta_link->sta;
+       struct ieee80211_link_sta *link_sta;
+       struct cfg80211_bitrate_mask mask;
+       struct mt7996_sta_link *msta_link;
+       struct mt7996_vif_link *link;
        struct sta_phy_uni phy = {};
-       int ret, nrates = 0;
+       struct ieee80211_sta *sta;
+       int ret, nrates = 0, idx;
+       enum nl80211_band band;
+       bool has_he;
 
 #define __sta_phy_bitrate_mask_check(_mcs, _gi, _ht, _he)                      \
        do {                                                                    \
-               u8 i, gi = mask->control[band]._gi;                             \
+               u8 i, gi = mask.control[band]._gi;                              \
                gi = (_he) ? gi : gi == NL80211_TXRATE_FORCE_SGI;               \
                phy.sgi = gi;                                                   \
-               phy.he_ltf = mask->control[band].he_ltf;                        \
-               for (i = 0; i < ARRAY_SIZE(mask->control[band]._mcs); i++) {    \
-                       if (!mask->control[band]._mcs[i])                       \
+               phy.he_ltf = mask.control[band].he_ltf;                         \
+               for (i = 0; i < ARRAY_SIZE(mask.control[band]._mcs); i++) {     \
+                       if (!mask.control[band]._mcs[i])                        \
                                continue;                                       \
-                       nrates += hweight16(mask->control[band]._mcs[i]);       \
-                       phy.mcs = ffs(mask->control[band]._mcs[i]) - 1;         \
+                       nrates += hweight16(mask.control[band]._mcs[i]);        \
+                       phy.mcs = ffs(mask.control[band]._mcs[i]) - 1;          \
                        if (_ht)                                                \
                                phy.mcs += 8 * i;                               \
                }                                                               \
        } while (0)
 
-       if (link_sta->he_cap.has_he) {
+       rcu_read_lock();
+
+       link = mt7996_vif_link(dev, vif, link_id);
+       if (!link)
+               goto error_unlock;
+
+       msta_link = rcu_dereference(msta->link[link_id]);
+       if (!msta_link)
+               goto error_unlock;
+
+       sta = wcid_to_sta(&msta_link->wcid);
+       link_sta = rcu_dereference(sta->link[link_id]);
+       if (!link_sta)
+               goto error_unlock;
+
+       band = link->phy->mt76->chandef.chan->band;
+       has_he = link_sta->he_cap.has_he;
+       mask = link->bitrate_mask;
+       idx = msta_link->wcid.idx;
+
+       if (has_he) {
                __sta_phy_bitrate_mask_check(he_mcs, he_gi, 0, 1);
        } else if (link_sta->vht_cap.vht_supported) {
                __sta_phy_bitrate_mask_check(vht_mcs, gi, 0, 0);
        } else if (link_sta->ht_cap.ht_supported) {
                __sta_phy_bitrate_mask_check(ht_mcs, gi, 1, 0);
        } else {
-               nrates = hweight32(mask->control[band].legacy);
-               phy.mcs = ffs(mask->control[band].legacy) - 1;
+               nrates = hweight32(mask.control[band].legacy);
+               phy.mcs = ffs(mask.control[band].legacy) - 1;
        }
+
+       rcu_read_unlock();
+
 #undef __sta_phy_bitrate_mask_check
 
        /* fall back to auto rate control */
-       if (mask->control[band].gi == NL80211_TXRATE_DEFAULT_GI &&
-           mask->control[band].he_gi == GENMASK(7, 0) &&
-           mask->control[band].he_ltf == GENMASK(7, 0) &&
+       if (mask.control[band].gi == NL80211_TXRATE_DEFAULT_GI &&
+           mask.control[band].he_gi == GENMASK(7, 0) &&
+           mask.control[band].he_ltf == GENMASK(7, 0) &&
            nrates != 1)
                return 0;
 
@@ -2034,16 +2057,16 @@ mt7996_mcu_add_rate_ctrl_fixed(struct mt7996_dev *dev,
        }
 
        /* fixed GI */
-       if (mask->control[band].gi != NL80211_TXRATE_DEFAULT_GI ||
-           mask->control[band].he_gi != GENMASK(7, 0)) {
+       if (mask.control[band].gi != NL80211_TXRATE_DEFAULT_GI ||
+           mask.control[band].he_gi != GENMASK(7, 0)) {
                u32 addr;
 
                /* firmware updates only TXCMD but doesn't take WTBL into
                 * account, so driver should update here to reflect the
                 * actual txrate hardware sends out.
                 */
-               addr = mt7996_mac_wtbl_lmac_addr(dev, msta_link->wcid.idx, 7);
-               if (link_sta->he_cap.has_he)
+               addr = mt7996_mac_wtbl_lmac_addr(dev, idx, 7);
+               if (has_he)
                        mt76_rmw_field(dev, addr, GENMASK(31, 24), phy.sgi);
                else
                        mt76_rmw_field(dev, addr, GENMASK(15, 12), phy.sgi);
@@ -2055,7 +2078,7 @@ mt7996_mcu_add_rate_ctrl_fixed(struct mt7996_dev *dev,
        }
 
        /* fixed HE_LTF */
-       if (mask->control[band].he_ltf != GENMASK(7, 0)) {
+       if (mask.control[band].he_ltf != GENMASK(7, 0)) {
                ret = mt7996_mcu_set_fixed_field(dev, msta, &phy, link_id,
                                                 RATE_PARAM_FIXED_HE_LTF);
                if (ret)
@@ -2063,6 +2086,11 @@ mt7996_mcu_add_rate_ctrl_fixed(struct mt7996_dev *dev,
        }
 
        return 0;
+
+error_unlock:
+       rcu_read_unlock();
+
+       return -ENODEV;
 }
 
 static void
@@ -2181,6 +2209,7 @@ int mt7996_mcu_add_rate_ctrl(struct mt7996_dev *dev,
                             struct mt7996_sta_link *msta_link,
                             u8 link_id, bool changed)
 {
+       struct mt7996_sta *msta = msta_link->sta;
        struct sk_buff *skb;
        int ret;
 
@@ -2207,8 +2236,7 @@ int mt7996_mcu_add_rate_ctrl(struct mt7996_dev *dev,
        if (ret)
                return ret;
 
-       return mt7996_mcu_add_rate_ctrl_fixed(dev, link_sta, link, msta_link,
-                                             link_id);
+       return mt7996_mcu_add_rate_ctrl_fixed(dev, msta, vif, link_id);
 }
 
 static int